diff --git a/include/linux/dept.h b/include/linux/dept.h new file mode 100644 index 00000000000000..f2a3057537d64c --- /dev/null +++ b/include/linux/dept.h @@ -0,0 +1,573 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * DEPT(DEPendency Tracker) - runtime dependency tracker + * + * Started by Byungchul Park : + * + * Copyright (c) 2020 LG Electronics, Inc., Byungchul Park + */ + +#ifndef __LINUX_DEPT_H +#define __LINUX_DEPT_H + +#ifdef CONFIG_DEPT + +#include + +struct task_struct; + +#define DEPT_MAX_STACK_ENTRY 16 +#define DEPT_MAX_WAIT_HIST 64 +#define DEPT_MAX_ECXT_HELD 48 + +#define DEPT_MAX_SUBCLASSES 16 +#define DEPT_MAX_SUBCLASSES_EVT 2 +#define DEPT_MAX_SUBCLASSES_USR (DEPT_MAX_SUBCLASSES / DEPT_MAX_SUBCLASSES_EVT) +#define DEPT_MAX_SUBCLASSES_CACHE 2 + +#define DEPT_SIRQ 0 +#define DEPT_HIRQ 1 +#define DEPT_IRQS_NR 2 +#define DEPT_SIRQF (1UL << DEPT_SIRQ) +#define DEPT_HIRQF (1UL << DEPT_HIRQ) + +struct dept_ecxt; +struct dept_iecxt { + struct dept_ecxt *ecxt; + int enirq; + /* + * for preventing to add a new ecxt + */ + bool staled; +}; + +struct dept_wait; +struct dept_iwait { + struct dept_wait *wait; + int irq; + /* + * for preventing to add a new wait + */ + bool staled; + bool touched; +}; + +struct dept_class { + union { + struct llist_node pool_node; + struct { + /* + * reference counter for object management + */ + atomic_t ref; + + /* + * unique information about the class + */ + const char *name; + unsigned long key; + int sub_id; + + /* + * for BFS + */ + unsigned int bfs_gen; + int bfs_dist; + struct dept_class *bfs_parent; + + /* + * for hashing this object + */ + struct hlist_node hash_node; + + /* + * for linking all classes + */ + struct list_head all_node; + + /* + * for associating its dependencies + */ + struct list_head dep_head; + struct list_head dep_rev_head; + + /* + * for tracking IRQ dependencies + */ + struct dept_iecxt iecxt[DEPT_IRQS_NR]; + struct dept_iwait iwait[DEPT_IRQS_NR]; + + /* + * classified by a map embedded in task_struct, + * not an explicit map + */ + bool sched_map; + }; + }; +}; + +struct dept_key { + union { + /* + * Each byte-wise address will be used as its key. + */ + char base[DEPT_MAX_SUBCLASSES]; + + /* + * for caching the main class pointer + */ + struct dept_class *classes[DEPT_MAX_SUBCLASSES_CACHE]; + }; +}; + +struct dept_map { + const char *name; + struct dept_key *keys; + + /* + * subclass that can be set from user + */ + int sub_u; + + /* + * It's local copy for fast access to the associated classes. + * Also used for dept_key for static maps. + */ + struct dept_key map_key; + + /* + * wait timestamp associated to this map + */ + unsigned int wgen; + + /* + * whether this map should be going to be checked or not + */ + bool nocheck; +}; + +#define DEPT_MAP_INITIALIZER(n, k) \ +{ \ + .name = #n, \ + .keys = (struct dept_key *)(k), \ + .sub_u = 0, \ + .map_key = { .classes = { NULL, } }, \ + .wgen = 0U, \ + .nocheck = false, \ +} + +struct dept_stack { + union { + struct llist_node pool_node; + struct { + /* + * reference counter for object management + */ + atomic_t ref; + + /* + * backtrace entries + */ + unsigned long raw[DEPT_MAX_STACK_ENTRY]; + int nr; + }; + }; +}; + +struct dept_ecxt { + union { + struct llist_node pool_node; + struct { + /* + * reference counter for object management + */ + atomic_t ref; + + /* + * function that entered to this ecxt + */ + const char *ecxt_fn; + + /* + * event function + */ + const char *event_fn; + + /* + * associated class + */ + struct dept_class *class; + + /* + * flag indicating which IRQ has been + * enabled within the event context + */ + unsigned long enirqf; + + /* + * where the IRQ-enabled happened + */ + unsigned long enirq_ip[DEPT_IRQS_NR]; + struct dept_stack *enirq_stack[DEPT_IRQS_NR]; + + /* + * where the event context started + */ + unsigned long ecxt_ip; + struct dept_stack *ecxt_stack; + + /* + * where the event triggered + */ + unsigned long event_ip; + struct dept_stack *event_stack; + }; + }; +}; + +struct dept_wait { + union { + struct llist_node pool_node; + struct { + /* + * reference counter for object management + */ + atomic_t ref; + + /* + * function causing this wait + */ + const char *wait_fn; + + /* + * the associated class + */ + struct dept_class *class; + + /* + * which IRQ the wait was placed in + */ + unsigned long irqf; + + /* + * where the IRQ wait happened + */ + unsigned long irq_ip[DEPT_IRQS_NR]; + struct dept_stack *irq_stack[DEPT_IRQS_NR]; + + /* + * where the wait happened + */ + unsigned long wait_ip; + struct dept_stack *wait_stack; + + /* + * whether this wait is for commit in scheduler + */ + bool sched_sleep; + }; + }; +}; + +struct dept_dep { + union { + struct llist_node pool_node; + struct { + /* + * reference counter for object management + */ + atomic_t ref; + + /* + * key data of dependency + */ + struct dept_ecxt *ecxt; + struct dept_wait *wait; + + /* + * This object can be referred without dept_lock + * held but with IRQ disabled, e.g. for hash + * lookup. So deferred deletion is needed. + */ + struct rcu_head rh; + + /* + * for BFS + */ + struct list_head bfs_node; + + /* + * for hashing this object + */ + struct hlist_node hash_node; + + /* + * for linking to a class object + */ + struct list_head dep_node; + struct list_head dep_rev_node; + }; + }; +}; + +struct dept_hash { + /* + * hash table + */ + struct hlist_head *table; + + /* + * size of the table e.i. 2^bits + */ + int bits; +}; + +struct dept_pool { + const char *name; + + /* + * object size + */ + size_t obj_sz; + + /* + * the number of the static array + */ + atomic_t obj_nr; + + /* + * offset of ->pool_node + */ + size_t node_off; + + /* + * pointer to the pool + */ + void *spool; + struct llist_head boot_pool; + struct llist_head __percpu *lpool; +}; + +struct dept_ecxt_held { + /* + * associated event context + */ + struct dept_ecxt *ecxt; + + /* + * unique key for this dept_ecxt_held + */ + struct dept_map *map; + + /* + * class of the ecxt of this dept_ecxt_held + */ + struct dept_class *class; + + /* + * the wgen when the event context started + */ + unsigned int wgen; + + /* + * subclass that only works in the local context + */ + int sub_l; +}; + +struct dept_wait_hist { + /* + * associated wait + */ + struct dept_wait *wait; + + /* + * unique id of all waits system-wise until wrapped + */ + unsigned int wgen; + + /* + * local context id to identify IRQ context + */ + unsigned int ctxt_id; +}; + +struct dept_task { + /* + * all event contexts that have entered and before exiting + */ + struct dept_ecxt_held ecxt_held[DEPT_MAX_ECXT_HELD]; + int ecxt_held_pos; + + /* + * ring buffer holding all waits that have happened + */ + struct dept_wait_hist wait_hist[DEPT_MAX_WAIT_HIST]; + int wait_hist_pos; + + /* + * sequential id to identify each IRQ context + */ + unsigned int irq_id[DEPT_IRQS_NR]; + + /* + * for tracking IRQ-enabled points with cross-event + */ + unsigned int wgen_enirq[DEPT_IRQS_NR]; + + /* + * for keeping up-to-date IRQ-enabled points + */ + unsigned long enirq_ip[DEPT_IRQS_NR]; + + /* + * current effective IRQ-enabled flag + */ + unsigned long eff_enirqf; + + /* + * for reserving a current stack instance at each operation + */ + struct dept_stack *stack; + + /* + * for preventing recursive call into DEPT engine + */ + int recursive; + + /* + * for staging data to commit a wait + */ + struct dept_map stage_m; + bool stage_sched_map; + const char *stage_w_fn; + unsigned long stage_ip; + + /* + * the number of missing ecxts + */ + int missing_ecxt; + + /* + * for tracking IRQ-enable state + */ + bool hardirqs_enabled; + bool softirqs_enabled; + + /* + * whether the current is on do_exit() + */ + bool task_exit; + + /* + * whether the current is running __schedule() + */ + bool in_sched; +}; + +#define DEPT_TASK_INITIALIZER(t) \ +{ \ + .wait_hist = { { .wait = NULL, } }, \ + .ecxt_held_pos = 0, \ + .wait_hist_pos = 0, \ + .irq_id = { 0U }, \ + .wgen_enirq = { 0U }, \ + .enirq_ip = { 0UL }, \ + .eff_enirqf = 0UL, \ + .stack = NULL, \ + .recursive = 0, \ + .stage_m = DEPT_MAP_INITIALIZER((t)->stage_m, NULL), \ + .stage_sched_map = false, \ + .stage_w_fn = NULL, \ + .stage_ip = 0UL, \ + .missing_ecxt = 0, \ + .hardirqs_enabled = false, \ + .softirqs_enabled = false, \ + .task_exit = false, \ + .in_sched = false, \ +} + +extern void dept_on(void); +extern void dept_off(void); +extern void dept_init(void); +extern void dept_task_init(struct task_struct *t); +extern void dept_task_exit(struct task_struct *t); +extern void dept_free_range(void *start, unsigned int sz); +extern void dept_map_init(struct dept_map *m, struct dept_key *k, int sub_u, const char *n); +extern void dept_map_reinit(struct dept_map *m, struct dept_key *k, int sub_u, const char *n); +extern void dept_map_copy(struct dept_map *to, struct dept_map *from); + +extern void dept_wait(struct dept_map *m, unsigned long w_f, unsigned long ip, const char *w_fn, int sub_l); +extern void dept_stage_wait(struct dept_map *m, struct dept_key *k, unsigned long ip, const char *w_fn, bool strong); +extern void dept_request_event_wait_commit(void); +extern void dept_clean_stage(void); +extern void dept_stage_event(struct task_struct *t, unsigned long ip); +extern void dept_ecxt_enter(struct dept_map *m, unsigned long e_f, unsigned long ip, const char *c_fn, const char *e_fn, int sub_l); +extern bool dept_ecxt_holding(struct dept_map *m, unsigned long e_f); +extern void dept_request_event(struct dept_map *m); +extern void dept_event(struct dept_map *m, unsigned long e_f, unsigned long ip, const char *e_fn); +extern void dept_ecxt_exit(struct dept_map *m, unsigned long e_f, unsigned long ip); +extern void dept_sched_enter(void); +extern void dept_sched_exit(void); + +static inline void dept_ecxt_enter_nokeep(struct dept_map *m) +{ + dept_ecxt_enter(m, 0UL, 0UL, NULL, NULL, 0); +} + +/* + * for users who want to manage external keys + */ +extern void dept_key_init(struct dept_key *k); +extern void dept_key_destroy(struct dept_key *k); +extern void dept_map_ecxt_modify(struct dept_map *m, unsigned long e_f, struct dept_key *new_k, unsigned long new_e_f, unsigned long new_ip, const char *new_c_fn, const char *new_e_fn, int new_sub_l); + +extern void dept_softirq_enter(void); +extern void dept_hardirq_enter(void); +extern void dept_softirqs_on(unsigned long ip); +extern void dept_hardirqs_on(unsigned long ip); +extern void dept_softirqs_off(unsigned long ip); +extern void dept_hardirqs_off(unsigned long ip); +#else /* !CONFIG_DEPT */ +struct dept_key { }; +struct dept_map { }; +struct dept_task { }; + +#define DEPT_MAP_INITIALIZER(n, k) { } +#define DEPT_TASK_INITIALIZER(t) { } + +#define dept_on() do { } while (0) +#define dept_off() do { } while (0) +#define dept_init() do { } while (0) +#define dept_task_init(t) do { } while (0) +#define dept_task_exit(t) do { } while (0) +#define dept_free_range(s, sz) do { } while (0) +#define dept_map_init(m, k, su, n) do { (void)(n); (void)(k); } while (0) +#define dept_map_reinit(m, k, su, n) do { (void)(n); (void)(k); } while (0) +#define dept_map_copy(t, f) do { } while (0) + +#define dept_wait(m, w_f, ip, w_fn, sl) do { (void)(w_fn); } while (0) +#define dept_stage_wait(m, k, ip, w_fn, s) do { (void)(k); (void)(w_fn); } while (0) +#define dept_request_event_wait_commit() do { } while (0) +#define dept_clean_stage() do { } while (0) +#define dept_stage_event(t, ip) do { } while (0) +#define dept_ecxt_enter(m, e_f, ip, c_fn, e_fn, sl) do { (void)(c_fn); (void)(e_fn); } while (0) +#define dept_ecxt_holding(m, e_f) false +#define dept_request_event(m) do { } while (0) +#define dept_event(m, e_f, ip, e_fn) do { (void)(e_fn); } while (0) +#define dept_ecxt_exit(m, e_f, ip) do { } while (0) +#define dept_sched_enter() do { } while (0) +#define dept_sched_exit() do { } while (0) +#define dept_ecxt_enter_nokeep(m) do { } while (0) +#define dept_key_init(k) do { (void)(k); } while (0) +#define dept_key_destroy(k) do { (void)(k); } while (0) +#define dept_map_ecxt_modify(m, e_f, n_k, n_e_f, n_ip, n_c_fn, n_e_fn, n_sl) do { (void)(n_k); (void)(n_c_fn); (void)(n_e_fn); } while (0) + +#define dept_softirq_enter() do { } while (0) +#define dept_hardirq_enter() do { } while (0) +#define dept_softirqs_on(ip) do { } while (0) +#define dept_hardirqs_on(ip) do { } while (0) +#define dept_softirqs_off(ip) do { } while (0) +#define dept_hardirqs_off(ip) do { } while (0) +#endif +#endif /* __LINUX_DEPT_H */ diff --git a/include/linux/hardirq.h b/include/linux/hardirq.h index d57cab4d4c06fd..bb279dbbe74806 100644 --- a/include/linux/hardirq.h +++ b/include/linux/hardirq.h @@ -5,6 +5,7 @@ #include #include #include +#include #include #include #include @@ -106,6 +107,7 @@ void irq_exit_rcu(void); */ #define __nmi_enter() \ do { \ + dept_off(); \ lockdep_off(); \ arch_nmi_enter(); \ BUG_ON(in_nmi() == NMI_MASK); \ @@ -128,6 +130,7 @@ void irq_exit_rcu(void); __preempt_count_sub(NMI_OFFSET + HARDIRQ_OFFSET); \ arch_nmi_exit(); \ lockdep_on(); \ + dept_on(); \ } while (0) #define nmi_exit() \ diff --git a/include/linux/sched.h b/include/linux/sched.h index 853d08f7562bda..fcb009900134bf 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -37,6 +37,7 @@ #include #include #include +#include /* task_struct member predeclarations (sorted alphabetically): */ struct audit_context; @@ -1168,6 +1169,8 @@ struct task_struct { struct held_lock held_locks[MAX_LOCK_DEPTH]; #endif + struct dept_task dept_task; + #if defined(CONFIG_UBSAN) && !defined(CONFIG_UBSAN_TRAP) unsigned int in_ubsan; #endif diff --git a/init/init_task.c b/init/init_task.c index ff6c4b9bfe6b1c..eb36ad68c912e9 100644 --- a/init/init_task.c +++ b/init/init_task.c @@ -12,6 +12,7 @@ #include #include #include +#include #include @@ -194,6 +195,7 @@ struct task_struct init_task .curr_chain_key = INITIAL_CHAIN_KEY, .lockdep_recursion = 0, #endif + .dept_task = DEPT_TASK_INITIALIZER(init_task), #ifdef CONFIG_FUNCTION_GRAPH_TRACER .ret_stack = NULL, .tracing_graph_pause = ATOMIC_INIT(0), diff --git a/init/main.c b/init/main.c index e1c3911d7c707d..6e5b492640b274 100644 --- a/init/main.c +++ b/init/main.c @@ -66,6 +66,7 @@ #include #include #include +#include #include #include #include @@ -1080,6 +1081,7 @@ asmlinkage __visible void __init __no_sanitize_address start_kernel(void) panic_param); lockdep_init(); + dept_init(); /* * Need to run this when irqs are enabled, because it wants diff --git a/kernel/Makefile b/kernel/Makefile index 10ef068f598d5d..d1eb49eaa73984 100644 --- a/kernel/Makefile +++ b/kernel/Makefile @@ -51,6 +51,7 @@ obj-y += livepatch/ obj-y += dma/ obj-y += entry/ obj-$(CONFIG_MODULES) += module/ +obj-y += dependency/ obj-$(CONFIG_KCMP) += kcmp.o obj-$(CONFIG_FREEZER) += freezer.o diff --git a/kernel/dependency/Makefile b/kernel/dependency/Makefile new file mode 100644 index 00000000000000..b5cfb8a03c0cf7 --- /dev/null +++ b/kernel/dependency/Makefile @@ -0,0 +1,3 @@ +# SPDX-License-Identifier: GPL-2.0 + +obj-$(CONFIG_DEPT) += dept.o diff --git a/kernel/dependency/dept.c b/kernel/dependency/dept.c new file mode 100644 index 00000000000000..a54a770e86c5ea --- /dev/null +++ b/kernel/dependency/dept.c @@ -0,0 +1,2980 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * DEPT(DEPendency Tracker) - Runtime dependency tracker + * + * Started by Byungchul Park : + * + * Copyright (c) 2020 LG Electronics, Inc., Byungchul Park + * + * DEPT provides a general way to detect deadlock possibility in runtime + * and the interest is not limited to typical lock but to every + * syncronization primitives. + * + * The following ideas were borrowed from LOCKDEP: + * + * 1) Use a graph to track relationship between classes. + * 2) Prevent performance regression using hash. + * + * The following items were enhanced from LOCKDEP: + * + * 1) Cover more deadlock cases. + * 2) Allow muliple reports. + * + * TODO: Both LOCKDEP and DEPT should co-exist until DEPT is considered + * stable. Then the dependency check routine should be replaced with + * DEPT after. It should finally look like: + * + * + * + * As is: + * + * LOCKDEP + * +-----------------------------------------+ + * | Lock usage correctness check | <-> locks + * | | + * | | + * | +-------------------------------------+ | + * | | Dependency check | | + * | | (by tracking lock acquisition order)| | + * | +-------------------------------------+ | + * | | + * +-----------------------------------------+ + * + * DEPT + * +-----------------------------------------+ + * | Dependency check | <-> waits/events + * | (by tracking wait and event context) | + * +-----------------------------------------+ + * + * + * + * To be: + * + * LOCKDEP + * +-----------------------------------------+ + * | Lock usage correctness check | <-> locks + * | | + * | | + * | (Request dependency check) | + * | T | + * +--------------------|--------------------+ + * | + * DEPT V + * +-----------------------------------------+ + * | Dependency check | <-> waits/events + * | (by tracking wait and event context) | + * +-----------------------------------------+ + */ + +#include +#include +#include +#include +#include +#include +#include + +static int dept_stop; +static int dept_per_cpu_ready; + +#define DEPT_READY_WARN (!oops_in_progress) + +/* + * Make all operations using DEPT_WARN_ON() fail on oops_in_progress and + * prevent warning message. + */ +#define DEPT_WARN_ON_ONCE(c) \ + ({ \ + int __ret = 0; \ + \ + if (likely(DEPT_READY_WARN)) \ + __ret = WARN_ONCE(c, "DEPT_WARN_ON_ONCE: " #c); \ + __ret; \ + }) + +#define DEPT_WARN_ONCE(s...) \ + ({ \ + if (likely(DEPT_READY_WARN)) \ + WARN_ONCE(1, "DEPT_WARN_ONCE: " s); \ + }) + +#define DEPT_WARN_ON(c) \ + ({ \ + int __ret = 0; \ + \ + if (likely(DEPT_READY_WARN)) \ + __ret = WARN(c, "DEPT_WARN_ON: " #c); \ + __ret; \ + }) + +#define DEPT_WARN(s...) \ + ({ \ + if (likely(DEPT_READY_WARN)) \ + WARN(1, "DEPT_WARN: " s); \ + }) + +#define DEPT_STOP(s...) \ + ({ \ + WRITE_ONCE(dept_stop, 1); \ + if (likely(DEPT_READY_WARN)) \ + WARN(1, "DEPT_STOP: " s); \ + }) + +#define DEPT_INFO_ONCE(s...) pr_warn_once("DEPT_INFO_ONCE: " s) + +static arch_spinlock_t dept_spin = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED; +static arch_spinlock_t stage_spin = (arch_spinlock_t)__ARCH_SPIN_LOCK_UNLOCKED; + +/* + * DEPT internal engine should be careful in using outside functions + * e.g. printk at reporting since that kind of usage might cause + * untrackable deadlock. + */ +static atomic_t dept_outworld = ATOMIC_INIT(0); + +static inline void dept_outworld_enter(void) +{ + atomic_inc(&dept_outworld); +} + +static inline void dept_outworld_exit(void) +{ + atomic_dec(&dept_outworld); +} + +static inline bool dept_outworld_entered(void) +{ + return atomic_read(&dept_outworld); +} + +static inline bool dept_lock(void) +{ + while (!arch_spin_trylock(&dept_spin)) + if (unlikely(dept_outworld_entered())) + return false; + return true; +} + +static inline void dept_unlock(void) +{ + arch_spin_unlock(&dept_spin); +} + +/* + * whether to stack-trace on every wait or every ecxt + */ +static bool rich_stack = true; + +enum bfs_ret { + BFS_CONTINUE, + BFS_CONTINUE_REV, + BFS_DONE, + BFS_SKIP, +}; + +static inline bool after(unsigned int a, unsigned int b) +{ + return (int)(b - a) < 0; +} + +static inline bool before(unsigned int a, unsigned int b) +{ + return (int)(a - b) < 0; +} + +static inline bool valid_stack(struct dept_stack *s) +{ + return s && s->nr > 0; +} + +static inline bool valid_class(struct dept_class *c) +{ + return c->key; +} + +static inline void invalidate_class(struct dept_class *c) +{ + c->key = 0UL; +} + +static inline struct dept_ecxt *dep_e(struct dept_dep *d) +{ + return d->ecxt; +} + +static inline struct dept_wait *dep_w(struct dept_dep *d) +{ + return d->wait; +} + +static inline struct dept_class *dep_fc(struct dept_dep *d) +{ + return dep_e(d)->class; +} + +static inline struct dept_class *dep_tc(struct dept_dep *d) +{ + return dep_w(d)->class; +} + +static inline const char *irq_str(int irq) +{ + if (irq == DEPT_SIRQ) + return "softirq"; + if (irq == DEPT_HIRQ) + return "hardirq"; + return "(unknown)"; +} + +static inline struct dept_task *dept_task(void) +{ + return ¤t->dept_task; +} + +/* + * Dept doesn't work either when it's stopped by DEPT_STOP() or in a nmi + * context. + */ +static inline bool dept_working(void) +{ + return !READ_ONCE(dept_stop) && !in_nmi(); +} + +/* + * Even k == NULL is considered as a valid key because it would use + * &->map_key as the key in that case. + */ +struct dept_key __dept_no_validate__; +static inline bool valid_key(struct dept_key *k) +{ + return &__dept_no_validate__ != k; +} + +/* + * Pool + * ===================================================================== + * DEPT maintains pools to provide objects in a safe way. + * + * 1) Static pool is used at the beginning of booting time. + * 2) Local pool is tried first before the static pool. Objects that + * have been freed will be placed. + */ + +enum object_t { +#define OBJECT(id, nr) OBJECT_##id, + #include "dept_object.h" +#undef OBJECT + OBJECT_NR, +}; + +#define OBJECT(id, nr) \ +static struct dept_##id spool_##id[nr]; \ +static DEFINE_PER_CPU(struct llist_head, lpool_##id); + #include "dept_object.h" +#undef OBJECT + +static struct dept_pool pool[OBJECT_NR] = { +#define OBJECT(id, nr) { \ + .name = #id, \ + .obj_sz = sizeof(struct dept_##id), \ + .obj_nr = ATOMIC_INIT(nr), \ + .node_off = offsetof(struct dept_##id, pool_node), \ + .spool = spool_##id, \ + .lpool = &lpool_##id, }, + #include "dept_object.h" +#undef OBJECT +}; + +/* + * Can use llist no matter whether CONFIG_ARCH_HAVE_NMI_SAFE_CMPXCHG is + * enabled or not because NMI and other contexts in the same CPU never + * run inside of DEPT concurrently by preventing reentrance. + */ +static void *from_pool(enum object_t t) +{ + struct dept_pool *p; + struct llist_head *h; + struct llist_node *n; + + /* + * llist_del_first() doesn't allow concurrent access e.g. + * between process and IRQ context. + */ + if (DEPT_WARN_ON(!irqs_disabled())) + return NULL; + + p = &pool[t]; + + /* + * Try local pool first. + */ + if (likely(dept_per_cpu_ready)) + h = this_cpu_ptr(p->lpool); + else + h = &p->boot_pool; + + n = llist_del_first(h); + if (n) + return (void *)n - p->node_off; + + /* + * Try static pool. + */ + if (atomic_read(&p->obj_nr) > 0) { + int idx = atomic_dec_return(&p->obj_nr); + + if (idx >= 0) + return p->spool + (idx * p->obj_sz); + } + + DEPT_INFO_ONCE("---------------------------------------------\n" + " Some of Dept internal resources are run out.\n" + " Dept might still work if the resources get freed.\n" + " However, the chances are Dept will suffer from\n" + " the lack from now. Needs to extend the internal\n" + " resource pools. Ask max.byungchul.park@gmail.com\n"); + return NULL; +} + +static void to_pool(void *o, enum object_t t) +{ + struct dept_pool *p = &pool[t]; + struct llist_head *h; + + preempt_disable(); + if (likely(dept_per_cpu_ready)) + h = this_cpu_ptr(p->lpool); + else + h = &p->boot_pool; + + llist_add(o + p->node_off, h); + preempt_enable(); +} + +#define OBJECT(id, nr) \ +static void (*ctor_##id)(struct dept_##id *a); \ +static void (*dtor_##id)(struct dept_##id *a); \ +static inline struct dept_##id *new_##id(void) \ +{ \ + struct dept_##id *a; \ + \ + a = (struct dept_##id *)from_pool(OBJECT_##id); \ + if (unlikely(!a)) \ + return NULL; \ + \ + atomic_set(&a->ref, 1); \ + \ + if (ctor_##id) \ + ctor_##id(a); \ + \ + return a; \ +} \ + \ +static inline struct dept_##id *get_##id(struct dept_##id *a) \ +{ \ + atomic_inc(&a->ref); \ + return a; \ +} \ + \ +static inline void put_##id(struct dept_##id *a) \ +{ \ + if (!atomic_dec_return(&a->ref)) { \ + if (dtor_##id) \ + dtor_##id(a); \ + to_pool(a, OBJECT_##id); \ + } \ +} \ + \ +static inline void del_##id(struct dept_##id *a) \ +{ \ + put_##id(a); \ +} \ + \ +static inline bool id##_consumed(struct dept_##id *a) \ +{ \ + return a && atomic_read(&a->ref) > 1; \ +} +#include "dept_object.h" +#undef OBJECT + +#define SET_CONSTRUCTOR(id, f) \ +static void (*ctor_##id)(struct dept_##id *a) = f + +static void initialize_dep(struct dept_dep *d) +{ + INIT_LIST_HEAD(&d->bfs_node); + INIT_LIST_HEAD(&d->dep_node); + INIT_LIST_HEAD(&d->dep_rev_node); +} +SET_CONSTRUCTOR(dep, initialize_dep); + +static void initialize_class(struct dept_class *c) +{ + int i; + + for (i = 0; i < DEPT_IRQS_NR; i++) { + struct dept_iecxt *ie = &c->iecxt[i]; + struct dept_iwait *iw = &c->iwait[i]; + + ie->ecxt = NULL; + ie->enirq = i; + ie->staled = false; + + iw->wait = NULL; + iw->irq = i; + iw->staled = false; + iw->touched = false; + } + c->bfs_gen = 0U; + + INIT_LIST_HEAD(&c->all_node); + INIT_LIST_HEAD(&c->dep_head); + INIT_LIST_HEAD(&c->dep_rev_head); +} +SET_CONSTRUCTOR(class, initialize_class); + +static void initialize_ecxt(struct dept_ecxt *e) +{ + int i; + + for (i = 0; i < DEPT_IRQS_NR; i++) { + e->enirq_stack[i] = NULL; + e->enirq_ip[i] = 0UL; + } + e->ecxt_ip = 0UL; + e->ecxt_stack = NULL; + e->enirqf = 0UL; + e->event_ip = 0UL; + e->event_stack = NULL; +} +SET_CONSTRUCTOR(ecxt, initialize_ecxt); + +static void initialize_wait(struct dept_wait *w) +{ + int i; + + for (i = 0; i < DEPT_IRQS_NR; i++) { + w->irq_stack[i] = NULL; + w->irq_ip[i] = 0UL; + } + w->wait_ip = 0UL; + w->wait_stack = NULL; + w->irqf = 0UL; +} +SET_CONSTRUCTOR(wait, initialize_wait); + +static void initialize_stack(struct dept_stack *s) +{ + s->nr = 0; +} +SET_CONSTRUCTOR(stack, initialize_stack); + +#define OBJECT(id, nr) \ +static void (*ctor_##id)(struct dept_##id *a); + #include "dept_object.h" +#undef OBJECT + +#undef SET_CONSTRUCTOR + +#define SET_DESTRUCTOR(id, f) \ +static void (*dtor_##id)(struct dept_##id *a) = f + +static void destroy_dep(struct dept_dep *d) +{ + if (dep_e(d)) + put_ecxt(dep_e(d)); + if (dep_w(d)) + put_wait(dep_w(d)); +} +SET_DESTRUCTOR(dep, destroy_dep); + +static void destroy_ecxt(struct dept_ecxt *e) +{ + int i; + + for (i = 0; i < DEPT_IRQS_NR; i++) + if (e->enirq_stack[i]) + put_stack(e->enirq_stack[i]); + if (e->class) + put_class(e->class); + if (e->ecxt_stack) + put_stack(e->ecxt_stack); + if (e->event_stack) + put_stack(e->event_stack); +} +SET_DESTRUCTOR(ecxt, destroy_ecxt); + +static void destroy_wait(struct dept_wait *w) +{ + int i; + + for (i = 0; i < DEPT_IRQS_NR; i++) + if (w->irq_stack[i]) + put_stack(w->irq_stack[i]); + if (w->class) + put_class(w->class); + if (w->wait_stack) + put_stack(w->wait_stack); +} +SET_DESTRUCTOR(wait, destroy_wait); + +#define OBJECT(id, nr) \ +static void (*dtor_##id)(struct dept_##id *a); + #include "dept_object.h" +#undef OBJECT + +#undef SET_DESTRUCTOR + +/* + * Caching and hashing + * ===================================================================== + * DEPT makes use of caching and hashing to improve performance. Each + * object can be obtained in O(1) with its key. + * + * NOTE: Currently we assume all the objects in the hashs will never be + * removed. Implement it when needed. + */ + +/* + * Some information might be lost but it's only for hashing key. + */ +static inline unsigned long mix(unsigned long a, unsigned long b) +{ + int halfbits = sizeof(unsigned long) * 8 / 2; + unsigned long halfmask = (1UL << halfbits) - 1UL; + + return (a << halfbits) | (b & halfmask); +} + +static bool cmp_dep(struct dept_dep *d1, struct dept_dep *d2) +{ + return dep_fc(d1)->key == dep_fc(d2)->key && + dep_tc(d1)->key == dep_tc(d2)->key; +} + +static unsigned long key_dep(struct dept_dep *d) +{ + return mix(dep_fc(d)->key, dep_tc(d)->key); +} + +static bool cmp_class(struct dept_class *c1, struct dept_class *c2) +{ + return c1->key == c2->key; +} + +static unsigned long key_class(struct dept_class *c) +{ + return c->key; +} + +#define HASH(id, bits) \ +static struct hlist_head table_##id[1UL << bits]; \ + \ +static inline struct hlist_head *head_##id(struct dept_##id *a) \ +{ \ + return table_##id + hash_long(key_##id(a), bits); \ +} \ + \ +static inline struct dept_##id *hash_lookup_##id(struct dept_##id *a) \ +{ \ + struct dept_##id *b; \ + \ + hlist_for_each_entry_rcu(b, head_##id(a), hash_node) \ + if (cmp_##id(a, b)) \ + return b; \ + return NULL; \ +} \ + \ +static inline void hash_add_##id(struct dept_##id *a) \ +{ \ + get_##id(a); \ + hlist_add_head_rcu(&a->hash_node, head_##id(a)); \ +} \ + \ +static inline void hash_del_##id(struct dept_##id *a) \ +{ \ + hlist_del_rcu(&a->hash_node); \ + put_##id(a); \ +} +#include "dept_hash.h" +#undef HASH + +static inline struct dept_dep *lookup_dep(struct dept_class *fc, + struct dept_class *tc) +{ + struct dept_ecxt onetime_e = { .class = fc }; + struct dept_wait onetime_w = { .class = tc }; + struct dept_dep onetime_d = { .ecxt = &onetime_e, + .wait = &onetime_w }; + return hash_lookup_dep(&onetime_d); +} + +static inline struct dept_class *lookup_class(unsigned long key) +{ + struct dept_class onetime_c = { .key = key }; + + return hash_lookup_class(&onetime_c); +} + +/* + * Report + * ===================================================================== + * DEPT prints useful information to help debuging on detection of + * problematic dependency. + */ + +static inline void print_ip_stack(unsigned long ip, struct dept_stack *s) +{ + if (ip) + print_ip_sym(KERN_WARNING, ip); + + if (valid_stack(s)) { + pr_warn("stacktrace:\n"); + stack_trace_print(s->raw, s->nr, 5); + } + + if (!ip && !valid_stack(s)) + pr_warn("(N/A)\n"); +} + +#define print_spc(spc, fmt, ...) \ + pr_warn("%*c" fmt, (spc) * 4, ' ', ##__VA_ARGS__) + +static void print_diagram(struct dept_dep *d) +{ + struct dept_ecxt *e = dep_e(d); + struct dept_wait *w = dep_w(d); + struct dept_class *fc = dep_fc(d); + struct dept_class *tc = dep_tc(d); + unsigned long irqf; + int irq; + bool firstline = true; + int spc = 1; + const char *w_fn = w->wait_fn ?: "(unknown)"; + const char *e_fn = e->event_fn ?: "(unknown)"; + const char *c_fn = e->ecxt_fn ?: "(unknown)"; + const char *fc_n = fc->sched_map ? "" : (fc->name ?: "(unknown)"); + const char *tc_n = tc->sched_map ? "" : (tc->name ?: "(unknown)"); + + irqf = e->enirqf & w->irqf; + for_each_set_bit(irq, &irqf, DEPT_IRQS_NR) { + if (!firstline) + pr_warn("\nor\n\n"); + firstline = false; + + print_spc(spc, "[S] %s(%s:%d)\n", c_fn, fc_n, fc->sub_id); + print_spc(spc, " <%s interrupt>\n", irq_str(irq)); + print_spc(spc + 1, "[W] %s(%s:%d)\n", w_fn, tc_n, tc->sub_id); + print_spc(spc, "[E] %s(%s:%d)\n", e_fn, fc_n, fc->sub_id); + } + + if (!irqf) { + print_spc(spc, "[S] %s(%s:%d)\n", c_fn, fc_n, fc->sub_id); + print_spc(spc, "[W] %s(%s:%d)\n", w_fn, tc_n, tc->sub_id); + print_spc(spc, "[E] %s(%s:%d)\n", e_fn, fc_n, fc->sub_id); + } +} + +static void print_dep(struct dept_dep *d) +{ + struct dept_ecxt *e = dep_e(d); + struct dept_wait *w = dep_w(d); + struct dept_class *fc = dep_fc(d); + struct dept_class *tc = dep_tc(d); + unsigned long irqf; + int irq; + const char *w_fn = w->wait_fn ?: "(unknown)"; + const char *e_fn = e->event_fn ?: "(unknown)"; + const char *c_fn = e->ecxt_fn ?: "(unknown)"; + const char *fc_n = fc->sched_map ? "" : (fc->name ?: "(unknown)"); + const char *tc_n = tc->sched_map ? "" : (tc->name ?: "(unknown)"); + + irqf = e->enirqf & w->irqf; + for_each_set_bit(irq, &irqf, DEPT_IRQS_NR) { + pr_warn("%s has been enabled:\n", irq_str(irq)); + print_ip_stack(e->enirq_ip[irq], e->enirq_stack[irq]); + pr_warn("\n"); + + pr_warn("[S] %s(%s:%d):\n", c_fn, fc_n, fc->sub_id); + print_ip_stack(e->ecxt_ip, e->ecxt_stack); + pr_warn("\n"); + + pr_warn("[W] %s(%s:%d) in %s context:\n", + w_fn, tc_n, tc->sub_id, irq_str(irq)); + print_ip_stack(w->irq_ip[irq], w->irq_stack[irq]); + pr_warn("\n"); + + pr_warn("[E] %s(%s:%d):\n", e_fn, fc_n, fc->sub_id); + print_ip_stack(e->event_ip, e->event_stack); + } + + if (!irqf) { + pr_warn("[S] %s(%s:%d):\n", c_fn, fc_n, fc->sub_id); + print_ip_stack(e->ecxt_ip, e->ecxt_stack); + pr_warn("\n"); + + pr_warn("[W] %s(%s:%d):\n", w_fn, tc_n, tc->sub_id); + print_ip_stack(w->wait_ip, w->wait_stack); + pr_warn("\n"); + + pr_warn("[E] %s(%s:%d):\n", e_fn, fc_n, fc->sub_id); + print_ip_stack(e->event_ip, e->event_stack); + } +} + +static void save_current_stack(int skip); + +/* + * Print all classes in a circle. + */ +static void print_circle(struct dept_class *c) +{ + struct dept_class *fc = c->bfs_parent; + struct dept_class *tc = c; + int i; + + dept_outworld_enter(); + save_current_stack(6); + + pr_warn("===================================================\n"); + pr_warn("DEPT: Circular dependency has been detected.\n"); + pr_warn("%s %.*s %s\n", init_utsname()->release, + (int)strcspn(init_utsname()->version, " "), + init_utsname()->version, + print_tainted()); + pr_warn("---------------------------------------------------\n"); + pr_warn("summary\n"); + pr_warn("---------------------------------------------------\n"); + + if (fc == tc) + pr_warn("*** AA DEADLOCK ***\n\n"); + else + pr_warn("*** DEADLOCK ***\n\n"); + + i = 0; + do { + struct dept_dep *d = lookup_dep(fc, tc); + + pr_warn("context %c\n", 'A' + (i++)); + print_diagram(d); + if (fc != c) + pr_warn("\n"); + + tc = fc; + fc = fc->bfs_parent; + } while (tc != c); + + pr_warn("\n"); + pr_warn("[S]: start of the event context\n"); + pr_warn("[W]: the wait blocked\n"); + pr_warn("[E]: the event not reachable\n"); + + i = 0; + do { + struct dept_dep *d = lookup_dep(fc, tc); + + pr_warn("---------------------------------------------------\n"); + pr_warn("context %c's detail\n", 'A' + i); + pr_warn("---------------------------------------------------\n"); + pr_warn("context %c\n", 'A' + (i++)); + print_diagram(d); + pr_warn("\n"); + print_dep(d); + + tc = fc; + fc = fc->bfs_parent; + } while (tc != c); + + pr_warn("---------------------------------------------------\n"); + pr_warn("information that might be helpful\n"); + pr_warn("---------------------------------------------------\n"); + dump_stack(); + + dept_outworld_exit(); +} + +/* + * BFS(Breadth First Search) + * ===================================================================== + * Whenever a new dependency is added into the graph, search the graph + * for a new circular dependency. + */ + +static inline void enqueue(struct list_head *h, struct dept_dep *d) +{ + list_add_tail(&d->bfs_node, h); +} + +static inline struct dept_dep *dequeue(struct list_head *h) +{ + struct dept_dep *d; + + d = list_first_entry(h, struct dept_dep, bfs_node); + list_del(&d->bfs_node); + return d; +} + +static inline bool empty(struct list_head *h) +{ + return list_empty(h); +} + +static void extend_queue(struct list_head *h, struct dept_class *cur) +{ + struct dept_dep *d; + + list_for_each_entry(d, &cur->dep_head, dep_node) { + struct dept_class *next = dep_tc(d); + + if (cur->bfs_gen == next->bfs_gen) + continue; + next->bfs_gen = cur->bfs_gen; + next->bfs_dist = cur->bfs_dist + 1; + next->bfs_parent = cur; + enqueue(h, d); + } +} + +static void extend_queue_rev(struct list_head *h, struct dept_class *cur) +{ + struct dept_dep *d; + + list_for_each_entry(d, &cur->dep_rev_head, dep_rev_node) { + struct dept_class *next = dep_fc(d); + + if (cur->bfs_gen == next->bfs_gen) + continue; + next->bfs_gen = cur->bfs_gen; + next->bfs_dist = cur->bfs_dist + 1; + next->bfs_parent = cur; + enqueue(h, d); + } +} + +typedef enum bfs_ret bfs_f(struct dept_dep *d, void *in, void **out); +static unsigned int bfs_gen; + +/* + * NOTE: Must be called with dept_lock held. + */ +static void bfs(struct dept_class *c, bfs_f *cb, void *in, void **out) +{ + LIST_HEAD(q); + enum bfs_ret ret; + + if (DEPT_WARN_ON(!cb)) + return; + + /* + * Avoid zero bfs_gen. + */ + bfs_gen = bfs_gen + 1 ?: 1; + + c->bfs_gen = bfs_gen; + c->bfs_dist = 0; + c->bfs_parent = c; + + ret = cb(NULL, in, out); + if (ret == BFS_DONE) + return; + if (ret == BFS_SKIP) + return; + if (ret == BFS_CONTINUE) + extend_queue(&q, c); + if (ret == BFS_CONTINUE_REV) + extend_queue_rev(&q, c); + + while (!empty(&q)) { + struct dept_dep *d = dequeue(&q); + + ret = cb(d, in, out); + if (ret == BFS_DONE) + break; + if (ret == BFS_SKIP) + continue; + if (ret == BFS_CONTINUE) + extend_queue(&q, dep_tc(d)); + if (ret == BFS_CONTINUE_REV) + extend_queue_rev(&q, dep_fc(d)); + } + + while (!empty(&q)) + dequeue(&q); +} + +/* + * Main operations + * ===================================================================== + * Add dependencies - Each new dependency is added into the graph and + * checked if it forms a circular dependency. + * + * Track waits - Waits are queued into the ring buffer for later use to + * generate appropriate dependencies with cross-event. + * + * Track event contexts(ecxt) - Event contexts are pushed into local + * stack for later use to generate appropriate dependencies with waits. + */ + +static inline unsigned long cur_enirqf(void); +static inline int cur_irq(void); +static inline unsigned int cur_ctxt_id(void); + +static inline struct dept_iecxt *iecxt(struct dept_class *c, int irq) +{ + return &c->iecxt[irq]; +} + +static inline struct dept_iwait *iwait(struct dept_class *c, int irq) +{ + return &c->iwait[irq]; +} + +static inline void stale_iecxt(struct dept_iecxt *ie) +{ + if (ie->ecxt) + put_ecxt(ie->ecxt); + + WRITE_ONCE(ie->ecxt, NULL); + WRITE_ONCE(ie->staled, true); +} + +static inline void set_iecxt(struct dept_iecxt *ie, struct dept_ecxt *e) +{ + /* + * ->ecxt will never be updated once getting set until the class + * gets removed. + */ + if (ie->ecxt) + DEPT_WARN_ON(1); + else + WRITE_ONCE(ie->ecxt, get_ecxt(e)); +} + +static inline void stale_iwait(struct dept_iwait *iw) +{ + if (iw->wait) + put_wait(iw->wait); + + WRITE_ONCE(iw->wait, NULL); + WRITE_ONCE(iw->staled, true); +} + +static inline void set_iwait(struct dept_iwait *iw, struct dept_wait *w) +{ + /* + * ->wait will never be updated once getting set until the class + * gets removed. + */ + if (iw->wait) + DEPT_WARN_ON(1); + else + WRITE_ONCE(iw->wait, get_wait(w)); + + iw->touched = true; +} + +static inline void touch_iwait(struct dept_iwait *iw) +{ + iw->touched = true; +} + +static inline void untouch_iwait(struct dept_iwait *iw) +{ + iw->touched = false; +} + +static inline struct dept_stack *get_current_stack(void) +{ + struct dept_stack *s = dept_task()->stack; + + return s ? get_stack(s) : NULL; +} + +static inline void prepare_current_stack(void) +{ + struct dept_stack *s = dept_task()->stack; + + /* + * The dept_stack is already ready. + */ + if (s && !stack_consumed(s)) { + s->nr = 0; + return; + } + + if (s) + put_stack(s); + + s = dept_task()->stack = new_stack(); + if (!s) + return; + + get_stack(s); + del_stack(s); +} + +static void save_current_stack(int skip) +{ + struct dept_stack *s = dept_task()->stack; + + if (!s) + return; + if (valid_stack(s)) + return; + + s->nr = stack_trace_save(s->raw, DEPT_MAX_STACK_ENTRY, skip); +} + +static void finish_current_stack(void) +{ + struct dept_stack *s = dept_task()->stack; + + if (stack_consumed(s)) + save_current_stack(2); +} + +/* + * FIXME: For now, disable LOCKDEP while DEPT is working. + * + * Both LOCKDEP and DEPT report it on a deadlock detection using + * printk taking the risk of another deadlock that might be caused by + * locks of console or printk between inside and outside of them. + * + * For DEPT, it's no problem since multiple reports are allowed. But it + * would be a bad idea for LOCKDEP since it will stop even on a singe + * report. So we need to prevent LOCKDEP from its reporting the risk + * DEPT would take when reporting something. + */ +#include + +void dept_off(void) +{ + dept_task()->recursive++; + lockdep_off(); +} + +void dept_on(void) +{ + dept_task()->recursive--; + lockdep_on(); +} + +static inline unsigned long dept_enter(void) +{ + unsigned long flags; + + flags = arch_local_irq_save(); + dept_off(); + prepare_current_stack(); + return flags; +} + +static inline void dept_exit(unsigned long flags) +{ + finish_current_stack(); + dept_on(); + arch_local_irq_restore(flags); +} + +static inline unsigned long dept_enter_recursive(void) +{ + unsigned long flags; + + flags = arch_local_irq_save(); + return flags; +} + +static inline void dept_exit_recursive(unsigned long flags) +{ + arch_local_irq_restore(flags); +} + +/* + * NOTE: Must be called with dept_lock held. + */ +static struct dept_dep *__add_dep(struct dept_ecxt *e, + struct dept_wait *w) +{ + struct dept_dep *d; + + if (DEPT_WARN_ON(!valid_class(e->class))) + return NULL; + + if (DEPT_WARN_ON(!valid_class(w->class))) + return NULL; + + if (lookup_dep(e->class, w->class)) + return NULL; + + d = new_dep(); + if (unlikely(!d)) + return NULL; + + d->ecxt = get_ecxt(e); + d->wait = get_wait(w); + + /* + * Add the dependency into hash and graph. + */ + hash_add_dep(d); + list_add(&d->dep_node, &dep_fc(d)->dep_head); + list_add(&d->dep_rev_node, &dep_tc(d)->dep_rev_head); + return d; +} + +static enum bfs_ret cb_check_dl(struct dept_dep *d, + void *in, void **out) +{ + struct dept_dep *new = (struct dept_dep *)in; + + /* + * initial condition for this BFS search + */ + if (!d) { + dep_tc(new)->bfs_parent = dep_fc(new); + + if (dep_tc(new) != dep_fc(new)) + return BFS_CONTINUE; + + /* + * AA circle does not make additional deadlock. We don't + * have to continue this BFS search. + */ + print_circle(dep_tc(new)); + return BFS_DONE; + } + + /* + * Allow multiple reports. + */ + if (dep_tc(d) == dep_fc(new)) + print_circle(dep_tc(new)); + + return BFS_CONTINUE; +} + +/* + * This function is actually in charge of reporting. + */ +static inline void check_dl_bfs(struct dept_dep *d) +{ + bfs(dep_tc(d), cb_check_dl, (void *)d, NULL); +} + +static enum bfs_ret cb_find_iw(struct dept_dep *d, void *in, void **out) +{ + int irq = *(int *)in; + struct dept_class *fc; + struct dept_iwait *iw; + + if (DEPT_WARN_ON(!out)) + return BFS_DONE; + + /* + * initial condition for this BFS search + */ + if (!d) + return BFS_CONTINUE_REV; + + fc = dep_fc(d); + iw = iwait(fc, irq); + + /* + * If any parent's ->wait was set, then the children would've + * been touched. + */ + if (!iw->touched) + return BFS_SKIP; + + if (!iw->wait) + return BFS_CONTINUE_REV; + + *out = iw; + return BFS_DONE; +} + +static struct dept_iwait *find_iw_bfs(struct dept_class *c, int irq) +{ + struct dept_iwait *iw = iwait(c, irq); + struct dept_iwait *found = NULL; + + if (iw->wait) + return iw; + + /* + * '->touched == false' guarantees there's no parent that has + * been set ->wait. + */ + if (!iw->touched) + return NULL; + + bfs(c, cb_find_iw, (void *)&irq, (void **)&found); + + if (found) + return found; + + untouch_iwait(iw); + return NULL; +} + +static enum bfs_ret cb_touch_iw_find_ie(struct dept_dep *d, void *in, + void **out) +{ + int irq = *(int *)in; + struct dept_class *tc; + struct dept_iecxt *ie; + struct dept_iwait *iw; + + if (DEPT_WARN_ON(!out)) + return BFS_DONE; + + /* + * initial condition for this BFS search + */ + if (!d) + return BFS_CONTINUE; + + tc = dep_tc(d); + ie = iecxt(tc, irq); + iw = iwait(tc, irq); + + touch_iwait(iw); + + if (!ie->ecxt) + return BFS_CONTINUE; + + if (!*out) + *out = ie; + + return BFS_CONTINUE; +} + +static struct dept_iecxt *touch_iw_find_ie_bfs(struct dept_class *c, + int irq) +{ + struct dept_iecxt *ie = iecxt(c, irq); + struct dept_iwait *iw = iwait(c, irq); + struct dept_iecxt *found = ie->ecxt ? ie : NULL; + + touch_iwait(iw); + bfs(c, cb_touch_iw_find_ie, (void *)&irq, (void **)&found); + return found; +} + +/* + * Should be called with dept_lock held. + */ +static void __add_idep(struct dept_iecxt *ie, struct dept_iwait *iw) +{ + struct dept_dep *new; + + /* + * There's nothing to do. + */ + if (!ie || !iw || !ie->ecxt || !iw->wait) + return; + + new = __add_dep(ie->ecxt, iw->wait); + + /* + * Deadlock detected. Let check_dl_bfs() report it. + */ + if (new) { + check_dl_bfs(new); + stale_iecxt(ie); + stale_iwait(iw); + } + + /* + * If !new, it would be the case of lack of object resource. + * Just let it go and get checked by other chances. Retrying is + * meaningless in that case. + */ +} + +static void set_check_iecxt(struct dept_class *c, int irq, + struct dept_ecxt *e) +{ + struct dept_iecxt *ie = iecxt(c, irq); + + set_iecxt(ie, e); + __add_idep(ie, find_iw_bfs(c, irq)); +} + +static void set_check_iwait(struct dept_class *c, int irq, + struct dept_wait *w) +{ + struct dept_iwait *iw = iwait(c, irq); + + set_iwait(iw, w); + __add_idep(touch_iw_find_ie_bfs(c, irq), iw); +} + +static void add_iecxt(struct dept_class *c, int irq, struct dept_ecxt *e, + bool stack) +{ + /* + * This access is safe since we ensure e->class has set locally. + */ + struct dept_task *dt = dept_task(); + struct dept_iecxt *ie = iecxt(c, irq); + + if (DEPT_WARN_ON(!valid_class(c))) + return; + + if (unlikely(READ_ONCE(ie->staled))) + return; + + /* + * Skip add_iecxt() if ie->ecxt has ever been set at least once. + * Which means it has a valid ->ecxt or been staled. + */ + if (READ_ONCE(ie->ecxt)) + return; + + if (unlikely(!dept_lock())) + return; + + if (unlikely(ie->staled)) + goto unlock; + if (ie->ecxt) + goto unlock; + + e->enirqf |= (1UL << irq); + + /* + * Should be NULL since it's the first time that these + * enirq_{ip,stack}[irq] have ever set. + */ + DEPT_WARN_ON(e->enirq_ip[irq]); + DEPT_WARN_ON(e->enirq_stack[irq]); + + e->enirq_ip[irq] = dt->enirq_ip[irq]; + e->enirq_stack[irq] = stack ? get_current_stack() : NULL; + + set_check_iecxt(c, irq, e); +unlock: + dept_unlock(); +} + +static void add_iwait(struct dept_class *c, int irq, struct dept_wait *w) +{ + struct dept_iwait *iw = iwait(c, irq); + + if (DEPT_WARN_ON(!valid_class(c))) + return; + + if (unlikely(READ_ONCE(iw->staled))) + return; + + /* + * Skip add_iwait() if iw->wait has ever been set at least once. + * Which means it has a valid ->wait or been staled. + */ + if (READ_ONCE(iw->wait)) + return; + + if (unlikely(!dept_lock())) + return; + + if (unlikely(iw->staled)) + goto unlock; + if (iw->wait) + goto unlock; + + w->irqf |= (1UL << irq); + + /* + * Should be NULL since it's the first time that these + * irq_{ip,stack}[irq] have ever set. + */ + DEPT_WARN_ON(w->irq_ip[irq]); + DEPT_WARN_ON(w->irq_stack[irq]); + + w->irq_ip[irq] = w->wait_ip; + w->irq_stack[irq] = get_current_stack(); + + set_check_iwait(c, irq, w); +unlock: + dept_unlock(); +} + +static inline struct dept_wait_hist *hist(int pos) +{ + struct dept_task *dt = dept_task(); + + return dt->wait_hist + (pos % DEPT_MAX_WAIT_HIST); +} + +static inline int hist_pos_next(void) +{ + struct dept_task *dt = dept_task(); + + return dt->wait_hist_pos % DEPT_MAX_WAIT_HIST; +} + +static inline void hist_advance(void) +{ + struct dept_task *dt = dept_task(); + + dt->wait_hist_pos++; + dt->wait_hist_pos %= DEPT_MAX_WAIT_HIST; +} + +static inline struct dept_wait_hist *new_hist(void) +{ + struct dept_wait_hist *wh = hist(hist_pos_next()); + + hist_advance(); + return wh; +} + +static void add_hist(struct dept_wait *w, unsigned int wg, unsigned int ctxt_id) +{ + struct dept_wait_hist *wh = new_hist(); + + if (likely(wh->wait)) + put_wait(wh->wait); + + wh->wait = get_wait(w); + wh->wgen = wg; + wh->ctxt_id = ctxt_id; +} + +/* + * Should be called after setting up e's iecxt and w's iwait. + */ +static void add_dep(struct dept_ecxt *e, struct dept_wait *w) +{ + struct dept_class *fc = e->class; + struct dept_class *tc = w->class; + struct dept_dep *d; + int i; + + if (lookup_dep(fc, tc)) + return; + + if (unlikely(!dept_lock())) + return; + + /* + * __add_dep() will lookup_dep() again with lock held. + */ + d = __add_dep(e, w); + if (d) { + check_dl_bfs(d); + + for (i = 0; i < DEPT_IRQS_NR; i++) { + struct dept_iwait *fiw = iwait(fc, i); + struct dept_iecxt *found_ie; + struct dept_iwait *found_iw; + + /* + * '->touched == false' guarantees there's no + * parent that has been set ->wait. + */ + if (!fiw->touched) + continue; + + /* + * find_iw_bfs() will untouch the iwait if + * not found. + */ + found_iw = find_iw_bfs(fc, i); + + if (!found_iw) + continue; + + found_ie = touch_iw_find_ie_bfs(tc, i); + __add_idep(found_ie, found_iw); + } + } + dept_unlock(); +} + +static atomic_t wgen = ATOMIC_INIT(1); + +static void add_wait(struct dept_class *c, unsigned long ip, + const char *w_fn, int sub_l, bool sched_sleep) +{ + struct dept_task *dt = dept_task(); + struct dept_wait *w; + unsigned int wg = 0U; + int irq; + int i; + + if (DEPT_WARN_ON(!valid_class(c))) + return; + + w = new_wait(); + if (unlikely(!w)) + return; + + WRITE_ONCE(w->class, get_class(c)); + w->wait_ip = ip; + w->wait_fn = w_fn; + w->wait_stack = get_current_stack(); + w->sched_sleep = sched_sleep; + + irq = cur_irq(); + if (irq < DEPT_IRQS_NR) + add_iwait(c, irq, w); + + /* + * Avoid adding dependency between user aware nested ecxt and + * wait. + */ + for (i = dt->ecxt_held_pos - 1; i >= 0; i--) { + struct dept_ecxt_held *eh; + + eh = dt->ecxt_held + i; + + /* + * the case of invalid key'ed one + */ + if (!eh->ecxt) + continue; + + if (eh->ecxt->class != c || eh->sub_l == sub_l) + add_dep(eh->ecxt, w); + } + + if (!wait_consumed(w) && !rich_stack) { + if (w->wait_stack) + put_stack(w->wait_stack); + w->wait_stack = NULL; + } + + /* + * Avoid zero wgen. + */ + wg = atomic_inc_return(&wgen) ?: atomic_inc_return(&wgen); + add_hist(w, wg, cur_ctxt_id()); + + del_wait(w); +} + +static bool add_ecxt(struct dept_map *m, struct dept_class *c, + unsigned long ip, const char *c_fn, + const char *e_fn, int sub_l) +{ + struct dept_task *dt = dept_task(); + struct dept_ecxt_held *eh; + struct dept_ecxt *e; + unsigned long irqf; + int irq; + + if (DEPT_WARN_ON(!valid_class(c))) + return false; + + if (DEPT_WARN_ON_ONCE(dt->ecxt_held_pos >= DEPT_MAX_ECXT_HELD)) + return false; + + if (m->nocheck) { + eh = dt->ecxt_held + (dt->ecxt_held_pos++); + eh->ecxt = NULL; + eh->map = m; + eh->class = get_class(c); + eh->wgen = atomic_read(&wgen); + eh->sub_l = sub_l; + + return true; + } + + e = new_ecxt(); + if (unlikely(!e)) + return false; + + e->class = get_class(c); + e->ecxt_ip = ip; + e->ecxt_stack = ip && rich_stack ? get_current_stack() : NULL; + e->event_fn = e_fn; + e->ecxt_fn = c_fn; + + eh = dt->ecxt_held + (dt->ecxt_held_pos++); + eh->ecxt = get_ecxt(e); + eh->map = m; + eh->class = get_class(c); + eh->wgen = atomic_read(&wgen); + eh->sub_l = sub_l; + + irqf = cur_enirqf(); + for_each_set_bit(irq, &irqf, DEPT_IRQS_NR) + add_iecxt(c, irq, e, false); + + del_ecxt(e); + return true; +} + +static int find_ecxt_pos(struct dept_map *m, struct dept_class *c, + bool newfirst) +{ + struct dept_task *dt = dept_task(); + int i; + + if (newfirst) { + for (i = dt->ecxt_held_pos - 1; i >= 0; i--) { + struct dept_ecxt_held *eh; + + eh = dt->ecxt_held + i; + if (eh->map == m && eh->class == c) + return i; + } + } else { + for (i = 0; i < dt->ecxt_held_pos; i++) { + struct dept_ecxt_held *eh; + + eh = dt->ecxt_held + i; + if (eh->map == m && eh->class == c) + return i; + } + } + return -1; +} + +static bool pop_ecxt(struct dept_map *m, struct dept_class *c) +{ + struct dept_task *dt = dept_task(); + int pos; + int i; + + pos = find_ecxt_pos(m, c, true); + if (pos == -1) + return false; + + if (dt->ecxt_held[pos].class) + put_class(dt->ecxt_held[pos].class); + + if (dt->ecxt_held[pos].ecxt) + put_ecxt(dt->ecxt_held[pos].ecxt); + + dt->ecxt_held_pos--; + + for (i = pos; i < dt->ecxt_held_pos; i++) + dt->ecxt_held[i] = dt->ecxt_held[i + 1]; + return true; +} + +static inline bool good_hist(struct dept_wait_hist *wh, unsigned int wg) +{ + return wh->wait != NULL && before(wg, wh->wgen); +} + +/* + * Binary-search the ring buffer for the earliest valid wait. + */ +static int find_hist_pos(unsigned int wg) +{ + int oldest; + int l; + int r; + int pos; + + oldest = hist_pos_next(); + if (unlikely(good_hist(hist(oldest), wg))) { + DEPT_INFO_ONCE("Need to expand the ring buffer.\n"); + return oldest; + } + + l = oldest + 1; + r = oldest + DEPT_MAX_WAIT_HIST - 1; + for (pos = (l + r) / 2; l <= r; pos = (l + r) / 2) { + struct dept_wait_hist *p = hist(pos - 1); + struct dept_wait_hist *wh = hist(pos); + + if (!good_hist(p, wg) && good_hist(wh, wg)) + return pos % DEPT_MAX_WAIT_HIST; + if (good_hist(wh, wg)) + r = pos - 1; + else + l = pos + 1; + } + return -1; +} + +static void do_event(struct dept_map *m, struct dept_class *c, + unsigned int wg, unsigned long ip) +{ + struct dept_task *dt = dept_task(); + struct dept_wait_hist *wh; + struct dept_ecxt_held *eh; + unsigned int ctxt_id; + int end; + int pos; + int i; + + if (DEPT_WARN_ON(!valid_class(c))) + return; + + if (m->nocheck) + return; + + /* + * The event was triggered before wait. + */ + if (!wg) + return; + + pos = find_ecxt_pos(m, c, false); + if (pos == -1) + return; + + eh = dt->ecxt_held + pos; + + if (DEPT_WARN_ON(!eh->ecxt)) + return; + + eh->ecxt->event_ip = ip; + eh->ecxt->event_stack = get_current_stack(); + + /* + * The ecxt already has done what it needs. + */ + if (!before(wg, eh->wgen)) + return; + + pos = find_hist_pos(wg); + if (pos == -1) + return; + + ctxt_id = cur_ctxt_id(); + end = hist_pos_next(); + end = end > pos ? end : end + DEPT_MAX_WAIT_HIST; + for (wh = hist(pos); pos < end; wh = hist(++pos)) { + if (after(wh->wgen, eh->wgen)) + break; + + if (dt->in_sched && wh->wait->sched_sleep) + continue; + + if (wh->ctxt_id == ctxt_id) + add_dep(eh->ecxt, wh->wait); + } + + for (i = 0; i < DEPT_IRQS_NR; i++) { + struct dept_ecxt *e; + + if (before(dt->wgen_enirq[i], wg)) + continue; + + e = eh->ecxt; + add_iecxt(e->class, i, e, false); + } +} + +static void del_dep_rcu(struct rcu_head *rh) +{ + struct dept_dep *d = container_of(rh, struct dept_dep, rh); + + preempt_disable(); + del_dep(d); + preempt_enable(); +} + +/* + * NOTE: Must be called with dept_lock held. + */ +static void disconnect_class(struct dept_class *c) +{ + struct dept_dep *d, *n; + int i; + + list_for_each_entry_safe(d, n, &c->dep_head, dep_node) { + list_del_rcu(&d->dep_node); + list_del_rcu(&d->dep_rev_node); + hash_del_dep(d); + call_rcu(&d->rh, del_dep_rcu); + } + + list_for_each_entry_safe(d, n, &c->dep_rev_head, dep_rev_node) { + list_del_rcu(&d->dep_node); + list_del_rcu(&d->dep_rev_node); + hash_del_dep(d); + call_rcu(&d->rh, del_dep_rcu); + } + + for (i = 0; i < DEPT_IRQS_NR; i++) { + stale_iecxt(iecxt(c, i)); + stale_iwait(iwait(c, i)); + } +} + +/* + * Context control + * ===================================================================== + * Whether a wait is in {hard,soft}-IRQ context or whether + * {hard,soft}-IRQ has been enabled on the way to an event is very + * important to check dependency. All those things should be tracked. + */ + +static inline unsigned long cur_enirqf(void) +{ + struct dept_task *dt = dept_task(); + int he = dt->hardirqs_enabled; + int se = dt->softirqs_enabled; + + if (he) + return DEPT_HIRQF | (se ? DEPT_SIRQF : 0UL); + return 0UL; +} + +static inline int cur_irq(void) +{ + if (lockdep_softirq_context(current)) + return DEPT_SIRQ; + if (lockdep_hardirq_context()) + return DEPT_HIRQ; + return DEPT_IRQS_NR; +} + +static inline unsigned int cur_ctxt_id(void) +{ + struct dept_task *dt = dept_task(); + int irq = cur_irq(); + + /* + * Normal process context + */ + if (irq == DEPT_IRQS_NR) + return 0U; + + return dt->irq_id[irq] | (1UL << irq); +} + +static void enirq_transition(int irq) +{ + struct dept_task *dt = dept_task(); + int i; + + /* + * READ wgen >= wgen of an event with IRQ enabled has been + * observed on the way to the event means, the IRQ can cut in + * within the ecxt. Used for cross-event detection. + * + * wait context event context(ecxt) + * ------------ ------------------- + * wait event + * WRITE wgen + * observe IRQ enabled + * READ wgen + * keep the wgen locally + * + * on the event + * check the local wgen + */ + dt->wgen_enirq[irq] = atomic_read(&wgen); + + for (i = dt->ecxt_held_pos - 1; i >= 0; i--) { + struct dept_ecxt_held *eh; + struct dept_ecxt *e; + + eh = dt->ecxt_held + i; + e = eh->ecxt; + if (e) + add_iecxt(e->class, irq, e, true); + } +} + +static void enirq_update(unsigned long ip) +{ + struct dept_task *dt = dept_task(); + unsigned long irqf; + unsigned long prev; + int irq; + + prev = dt->eff_enirqf; + irqf = cur_enirqf(); + dt->eff_enirqf = irqf; + + /* + * Do enirq_transition() only on an OFF -> ON transition. + */ + for_each_set_bit(irq, &irqf, DEPT_IRQS_NR) { + if (prev & (1UL << irq)) + continue; + + dt->enirq_ip[irq] = ip; + enirq_transition(irq); + } +} + +/* + * Ensure it has been called on ON/OFF transition. + */ +static void dept_enirq_transition(unsigned long ip) +{ + struct dept_task *dt = dept_task(); + unsigned long flags; + + if (unlikely(!dept_working())) + return; + + /* + * IRQ ON/OFF transition might happen while Dept is working. + * We cannot handle recursive entrance. Just ingnore it. + * Only transitions outside of Dept will be considered. + */ + if (dt->recursive) + return; + + flags = dept_enter(); + + enirq_update(ip); + + dept_exit(flags); +} + +void dept_softirqs_on(unsigned long ip) +{ + /* + * Assumes that it's called with IRQ disabled so that accessing + * current's fields is not racy. + */ + dept_task()->softirqs_enabled = true; + dept_enirq_transition(ip); +} + +void dept_hardirqs_on(unsigned long ip) +{ + /* + * Assumes that it's called with IRQ disabled so that accessing + * current's fields is not racy. + */ + dept_task()->hardirqs_enabled = true; + dept_enirq_transition(ip); +} +EXPORT_SYMBOL_GPL(dept_hardirqs_on); + +void dept_softirqs_off(unsigned long ip) +{ + /* + * Assumes that it's called with IRQ disabled so that accessing + * current's fields is not racy. + */ + dept_task()->softirqs_enabled = false; + dept_enirq_transition(ip); +} + +void dept_hardirqs_off(unsigned long ip) +{ + /* + * Assumes that it's called with IRQ disabled so that accessing + * current's fields is not racy. + */ + dept_task()->hardirqs_enabled = false; + dept_enirq_transition(ip); +} +EXPORT_SYMBOL_GPL(dept_hardirqs_off); + +/* + * Ensure it's the outmost softirq context. + */ +void dept_softirq_enter(void) +{ + struct dept_task *dt = dept_task(); + + dt->irq_id[DEPT_SIRQ] += 1UL << DEPT_IRQS_NR; +} + +/* + * Ensure it's the outmost hardirq context. + */ +void dept_hardirq_enter(void) +{ + struct dept_task *dt = dept_task(); + + dt->irq_id[DEPT_HIRQ] += 1UL << DEPT_IRQS_NR; +} + +void dept_sched_enter(void) +{ + dept_task()->in_sched = true; +} + +void dept_sched_exit(void) +{ + dept_task()->in_sched = false; +} + +/* + * Exposed APIs + * ===================================================================== + */ + +static inline void clean_classes_cache(struct dept_key *k) +{ + int i; + + for (i = 0; i < DEPT_MAX_SUBCLASSES_CACHE; i++) { + if (!READ_ONCE(k->classes[i])) + continue; + + WRITE_ONCE(k->classes[i], NULL); + } +} + +void dept_map_init(struct dept_map *m, struct dept_key *k, int sub_u, + const char *n) +{ + unsigned long flags; + + if (unlikely(!dept_working())) { + m->nocheck = true; + return; + } + + if (DEPT_WARN_ON(sub_u < 0)) { + m->nocheck = true; + return; + } + + if (DEPT_WARN_ON(sub_u >= DEPT_MAX_SUBCLASSES_USR)) { + m->nocheck = true; + return; + } + + /* + * Allow recursive entrance. + */ + flags = dept_enter_recursive(); + + clean_classes_cache(&m->map_key); + + m->keys = k; + m->sub_u = sub_u; + m->name = n; + m->wgen = 0U; + m->nocheck = !valid_key(k); + + dept_exit_recursive(flags); +} +EXPORT_SYMBOL_GPL(dept_map_init); + +void dept_map_reinit(struct dept_map *m, struct dept_key *k, int sub_u, + const char *n) +{ + unsigned long flags; + + if (unlikely(!dept_working())) { + m->nocheck = true; + return; + } + + /* + * Allow recursive entrance. + */ + flags = dept_enter_recursive(); + + if (k) { + clean_classes_cache(&m->map_key); + m->keys = k; + m->nocheck = !valid_key(k); + } + + if (sub_u >= 0 && sub_u < DEPT_MAX_SUBCLASSES_USR) + m->sub_u = sub_u; + + if (n) + m->name = n; + + m->wgen = 0U; + + dept_exit_recursive(flags); +} +EXPORT_SYMBOL_GPL(dept_map_reinit); + +void dept_map_copy(struct dept_map *to, struct dept_map *from) +{ + if (unlikely(!dept_working())) { + to->nocheck = true; + return; + } + + *to = *from; + + /* + * XXX: 'to' might be in a stack or something. Using the address + * in a stack segment as a key is meaningless. Just ignore the + * case for now. + */ + if (!to->keys) { + to->nocheck = true; + return; + } + + /* + * Since the class cache can be modified concurrently we could + * observe half pointers (64bit arch using 32bit copy insns). + * Therefore clear the caches and take the performance hit. + * + * XXX: Doesn't work well with lockdep_set_class_and_subclass() + * since that relies on cache abuse. + */ + clean_classes_cache(&to->map_key); +} + +static LIST_HEAD(classes); + +static inline bool within(const void *addr, void *start, unsigned long size) +{ + return addr >= start && addr < start + size; +} + +void dept_free_range(void *start, unsigned int sz) +{ + struct dept_task *dt = dept_task(); + struct dept_class *c, *n; + unsigned long flags; + + if (unlikely(!dept_working())) + return; + + if (dt->recursive) { + DEPT_STOP("Failed to successfully free Dept objects.\n"); + return; + } + + flags = dept_enter(); + + /* + * dept_free_range() should not fail. + * + * FIXME: Should be fixed if dept_free_range() causes deadlock + * with dept_lock(). + */ + while (unlikely(!dept_lock())) + cpu_relax(); + + list_for_each_entry_safe(c, n, &classes, all_node) { + if (!within((void *)c->key, start, sz) && + !within(c->name, start, sz)) + continue; + + hash_del_class(c); + disconnect_class(c); + list_del(&c->all_node); + invalidate_class(c); + + /* + * Actual deletion will happen on the rcu callback + * that has been added in disconnect_class(). + */ + del_class(c); + } + dept_unlock(); + dept_exit(flags); + + /* + * Wait until even lockless hash_lookup_class() for the class + * returns NULL. + */ + might_sleep(); + synchronize_rcu(); +} + +static inline int sub_id(struct dept_map *m, int e) +{ + return (m ? m->sub_u : 0) + e * DEPT_MAX_SUBCLASSES_USR; +} + +static struct dept_class *check_new_class(struct dept_key *local, + struct dept_key *k, int sub_id, + const char *n, bool sched_map) +{ + struct dept_class *c = NULL; + + if (DEPT_WARN_ON(sub_id >= DEPT_MAX_SUBCLASSES)) + return NULL; + + if (DEPT_WARN_ON(!k)) + return NULL; + + /* + * XXX: Assume that users prevent the map from using if any of + * the cached keys has been invalidated. If not, the cache, + * local->classes should not be used because it would be racy + * with class deletion. + */ + if (local && sub_id < DEPT_MAX_SUBCLASSES_CACHE) + c = READ_ONCE(local->classes[sub_id]); + + if (c) + return c; + + c = lookup_class((unsigned long)k->base + sub_id); + if (c) + goto caching; + + if (unlikely(!dept_lock())) + return NULL; + + c = lookup_class((unsigned long)k->base + sub_id); + if (unlikely(c)) + goto unlock; + + c = new_class(); + if (unlikely(!c)) + goto unlock; + + c->name = n; + c->sched_map = sched_map; + c->sub_id = sub_id; + c->key = (unsigned long)(k->base + sub_id); + hash_add_class(c); + list_add(&c->all_node, &classes); +unlock: + dept_unlock(); +caching: + if (local && sub_id < DEPT_MAX_SUBCLASSES_CACHE) + WRITE_ONCE(local->classes[sub_id], c); + + return c; +} + +/* + * Called between dept_enter() and dept_exit(). + */ +static void __dept_wait(struct dept_map *m, unsigned long w_f, + unsigned long ip, const char *w_fn, int sub_l, + bool sched_sleep, bool sched_map) +{ + int e; + + /* + * Be as conservative as possible. In case of mulitple waits for + * a single dept_map, we are going to keep only the last wait's + * wgen for simplicity - keeping all wgens seems overengineering. + * + * Of course, it might cause missing some dependencies that + * would rarely, probabily never, happen but it helps avoid + * false positive report. + */ + for_each_set_bit(e, &w_f, DEPT_MAX_SUBCLASSES_EVT) { + struct dept_class *c; + struct dept_key *k; + + k = m->keys ?: &m->map_key; + c = check_new_class(&m->map_key, k, + sub_id(m, e), m->name, sched_map); + if (!c) + continue; + + add_wait(c, ip, w_fn, sub_l, sched_sleep); + } +} + +/* + * Called between dept_enter() and dept_exit(). + */ +static void __dept_event(struct dept_map *m, unsigned long e_f, + unsigned long ip, const char *e_fn, + bool sched_map) +{ + struct dept_class *c; + struct dept_key *k; + int e; + + e = find_first_bit(&e_f, DEPT_MAX_SUBCLASSES_EVT); + + if (DEPT_WARN_ON(e >= DEPT_MAX_SUBCLASSES_EVT)) + goto exit; + + /* + * An event is an event. If the caller passed more than single + * event, then warn it and handle the event corresponding to + * the first bit anyway. + */ + DEPT_WARN_ON(1UL << e != e_f); + + k = m->keys ?: &m->map_key; + c = check_new_class(&m->map_key, k, sub_id(m, e), m->name, sched_map); + + if (c && add_ecxt(m, c, 0UL, NULL, e_fn, 0)) { + do_event(m, c, READ_ONCE(m->wgen), ip); + pop_ecxt(m, c); + } +exit: + /* + * Keep the map diabled until the next sleep. + */ + WRITE_ONCE(m->wgen, 0U); +} + +void dept_wait(struct dept_map *m, unsigned long w_f, + unsigned long ip, const char *w_fn, int sub_l) +{ + struct dept_task *dt = dept_task(); + unsigned long flags; + + if (unlikely(!dept_working())) + return; + + if (dt->recursive) + return; + + if (m->nocheck) + return; + + flags = dept_enter(); + + __dept_wait(m, w_f, ip, w_fn, sub_l, false, false); + + dept_exit(flags); +} +EXPORT_SYMBOL_GPL(dept_wait); + +void dept_stage_wait(struct dept_map *m, struct dept_key *k, + unsigned long ip, const char *w_fn, bool strong) +{ + struct dept_task *dt = dept_task(); + unsigned long flags; + + if (unlikely(!dept_working())) + return; + + if (m && m->nocheck) + return; + + /* + * Either m or k should be passed. Which means Dept relies on + * either its own map or the caller's position in the code when + * determining its class. + */ + if (DEPT_WARN_ON(!m && !k)) + return; + + /* + * Allow recursive entrance. + */ + flags = dept_enter_recursive(); + + arch_spin_lock(&stage_spin); + + if (!strong && dt->stage_m.keys) + goto unlock; + + if (m) { + dt->stage_m = *m; + + /* + * Ensure dt->stage_m.keys != NULL and it works with the + * map's map_key, not stage_m's one when ->keys == NULL. + */ + if (!m->keys) + dt->stage_m.keys = &m->map_key; + } else { + dt->stage_m.name = w_fn; + dt->stage_sched_map = true; + } + + /* + * dept_map_reinit() includes WRITE_ONCE(->wgen, 0U) that + * effectively disables the map just in case real sleep won't + * happen. dept_request_event_wait_commit() will enable it. + */ + dept_map_reinit(&dt->stage_m, k, -1, NULL); + + dt->stage_w_fn = w_fn; + dt->stage_ip = ip; +unlock: + arch_spin_unlock(&stage_spin); + + dept_exit_recursive(flags); +} +EXPORT_SYMBOL_GPL(dept_stage_wait); + +void dept_clean_stage(void) +{ + struct dept_task *dt = dept_task(); + unsigned long flags; + + if (unlikely(!dept_working())) + return; + + /* + * Allow recursive entrance. + */ + flags = dept_enter_recursive(); + + arch_spin_lock(&stage_spin); + memset(&dt->stage_m, 0x0, sizeof(struct dept_map)); + dt->stage_sched_map = false; + dt->stage_w_fn = NULL; + dt->stage_ip = 0UL; + arch_spin_unlock(&stage_spin); + + dept_exit_recursive(flags); +} +EXPORT_SYMBOL_GPL(dept_clean_stage); + +/* + * Always called from __schedule(). + */ +void dept_request_event_wait_commit(void) +{ + struct dept_task *dt = dept_task(); + unsigned long flags; + unsigned int wg; + unsigned long ip; + const char *w_fn; + bool sched_map; + + if (unlikely(!dept_working())) + return; + + /* + * It's impossible that __schedule() is called while Dept is + * working that already disabled IRQ at the entrance. + */ + if (DEPT_WARN_ON(dt->recursive)) + return; + + flags = dept_enter(); + + /* + * Checks if current has staged a wait. + */ + if (!dt->stage_m.keys) + goto exit; + + w_fn = dt->stage_w_fn; + ip = dt->stage_ip; + sched_map = dt->stage_sched_map; + + /* + * Avoid zero wgen. + */ + wg = atomic_inc_return(&wgen) ?: atomic_inc_return(&wgen); + WRITE_ONCE(dt->stage_m.wgen, wg); + + __dept_wait(&dt->stage_m, 1UL, ip, w_fn, 0, true, sched_map); +exit: + dept_exit(flags); +} + +/* + * Always called from try_to_wake_up(). + */ +void dept_stage_event(struct task_struct *t, unsigned long ip) +{ + struct dept_task *dt = dept_task(); + unsigned long flags; + struct dept_map m; + bool sched_map; + + if (unlikely(!dept_working())) + return; + + if (dt->recursive) + return; + + flags = dept_enter(); + + arch_spin_lock(&stage_spin); + m = dt->stage_m; + sched_map = dt->stage_sched_map; + arch_spin_unlock(&stage_spin); + + /* + * ->stage_m.keys should not be NULL if it's in use. Should + * make sure that it's not NULL when staging a valid map. + */ + if (!m.keys) + goto exit; + + __dept_event(&m, 1UL, ip, "try_to_wake_up", sched_map); +exit: + dept_exit(flags); +} + +/* + * Modifies the latest ecxt corresponding to m and e_f. + */ +void dept_map_ecxt_modify(struct dept_map *m, unsigned long e_f, + struct dept_key *new_k, unsigned long new_e_f, + unsigned long new_ip, const char *new_c_fn, + const char *new_e_fn, int new_sub_l) +{ + struct dept_task *dt = dept_task(); + struct dept_ecxt_held *eh; + struct dept_class *c; + struct dept_key *k; + unsigned long flags; + int pos = -1; + int new_e; + int e; + + if (unlikely(!dept_working())) + return; + + /* + * XXX: Couldn't handle re-enterance cases. Ingore it for now. + */ + if (dt->recursive) + return; + + /* + * Should go ahead no matter whether ->nocheck == true or not + * because ->nocheck value can be changed within the ecxt area + * delimitated by dept_ecxt_enter() and dept_ecxt_exit(). + */ + + flags = dept_enter(); + + for_each_set_bit(e, &e_f, DEPT_MAX_SUBCLASSES_EVT) { + k = m->keys ?: &m->map_key; + c = check_new_class(&m->map_key, k, + sub_id(m, e), m->name, false); + if (!c) + continue; + + /* + * When it found an ecxt for any event in e_f, done. + */ + pos = find_ecxt_pos(m, c, true); + if (pos != -1) + break; + } + + if (unlikely(pos == -1)) + goto exit; + + eh = dt->ecxt_held + pos; + new_sub_l = new_sub_l >= 0 ? new_sub_l : eh->sub_l; + + new_e = find_first_bit(&new_e_f, DEPT_MAX_SUBCLASSES_EVT); + + if (new_e < DEPT_MAX_SUBCLASSES_EVT) + /* + * Let it work with the first bit anyway. + */ + DEPT_WARN_ON(1UL << new_e != new_e_f); + else + new_e = e; + + pop_ecxt(m, c); + + /* + * Apply the key to the map. + */ + if (new_k) + dept_map_reinit(m, new_k, -1, NULL); + + k = m->keys ?: &m->map_key; + c = check_new_class(&m->map_key, k, sub_id(m, new_e), m->name, false); + + if (c && add_ecxt(m, c, new_ip, new_c_fn, new_e_fn, new_sub_l)) + goto exit; + + /* + * Successfully pop_ecxt()ed but failed to add_ecxt(). + */ + dt->missing_ecxt++; +exit: + dept_exit(flags); +} +EXPORT_SYMBOL_GPL(dept_map_ecxt_modify); + +void dept_ecxt_enter(struct dept_map *m, unsigned long e_f, unsigned long ip, + const char *c_fn, const char *e_fn, int sub_l) +{ + struct dept_task *dt = dept_task(); + unsigned long flags; + struct dept_class *c; + struct dept_key *k; + int e; + + if (unlikely(!dept_working())) + return; + + if (dt->recursive) { + dt->missing_ecxt++; + return; + } + + /* + * Should go ahead no matter whether ->nocheck == true or not + * because ->nocheck value can be changed within the ecxt area + * delimitated by dept_ecxt_enter() and dept_ecxt_exit(). + */ + + flags = dept_enter(); + + e = find_first_bit(&e_f, DEPT_MAX_SUBCLASSES_EVT); + + if (e >= DEPT_MAX_SUBCLASSES_EVT) + goto missing_ecxt; + + /* + * An event is an event. If the caller passed more than single + * event, then warn it and handle the event corresponding to + * the first bit anyway. + */ + DEPT_WARN_ON(1UL << e != e_f); + + k = m->keys ?: &m->map_key; + c = check_new_class(&m->map_key, k, sub_id(m, e), m->name, false); + + if (c && add_ecxt(m, c, ip, c_fn, e_fn, sub_l)) + goto exit; +missing_ecxt: + dt->missing_ecxt++; +exit: + dept_exit(flags); +} +EXPORT_SYMBOL_GPL(dept_ecxt_enter); + +bool dept_ecxt_holding(struct dept_map *m, unsigned long e_f) +{ + struct dept_task *dt = dept_task(); + unsigned long flags; + bool ret = false; + int e; + + if (unlikely(!dept_working())) + return false; + + if (dt->recursive) + return false; + + flags = dept_enter(); + + for_each_set_bit(e, &e_f, DEPT_MAX_SUBCLASSES_EVT) { + struct dept_class *c; + struct dept_key *k; + + k = m->keys ?: &m->map_key; + c = check_new_class(&m->map_key, k, + sub_id(m, e), m->name, false); + if (!c) + continue; + + if (find_ecxt_pos(m, c, true) != -1) { + ret = true; + break; + } + } + + dept_exit(flags); + + return ret; +} +EXPORT_SYMBOL_GPL(dept_ecxt_holding); + +void dept_request_event(struct dept_map *m) +{ + unsigned long flags; + unsigned int wg; + + if (unlikely(!dept_working())) + return; + + if (m->nocheck) + return; + + /* + * Allow recursive entrance. + */ + flags = dept_enter_recursive(); + + /* + * Avoid zero wgen. + */ + wg = atomic_inc_return(&wgen) ?: atomic_inc_return(&wgen); + WRITE_ONCE(m->wgen, wg); + + dept_exit_recursive(flags); +} +EXPORT_SYMBOL_GPL(dept_request_event); + +void dept_event(struct dept_map *m, unsigned long e_f, + unsigned long ip, const char *e_fn) +{ + struct dept_task *dt = dept_task(); + unsigned long flags; + + if (unlikely(!dept_working())) + return; + + if (dt->recursive) { + /* + * Dept won't work with this even though an event + * context has been asked. Don't make it confused at + * handling the event. Disable it until the next. + */ + WRITE_ONCE(m->wgen, 0U); + return; + } + + if (m->nocheck) + return; + + flags = dept_enter(); + + __dept_event(m, e_f, ip, e_fn, false); + + dept_exit(flags); +} +EXPORT_SYMBOL_GPL(dept_event); + +void dept_ecxt_exit(struct dept_map *m, unsigned long e_f, + unsigned long ip) +{ + struct dept_task *dt = dept_task(); + unsigned long flags; + int e; + + if (unlikely(!dept_working())) + return; + + if (dt->recursive) { + dt->missing_ecxt--; + return; + } + + /* + * Should go ahead no matter whether ->nocheck == true or not + * because ->nocheck value can be changed within the ecxt area + * delimitated by dept_ecxt_enter() and dept_ecxt_exit(). + */ + + flags = dept_enter(); + + for_each_set_bit(e, &e_f, DEPT_MAX_SUBCLASSES_EVT) { + struct dept_class *c; + struct dept_key *k; + + k = m->keys ?: &m->map_key; + c = check_new_class(&m->map_key, k, + sub_id(m, e), m->name, false); + if (!c) + continue; + + /* + * When it found an ecxt for any event in e_f, done. + */ + if (pop_ecxt(m, c)) + goto exit; + } + + dt->missing_ecxt--; +exit: + dept_exit(flags); +} +EXPORT_SYMBOL_GPL(dept_ecxt_exit); + +void dept_task_exit(struct task_struct *t) +{ + struct dept_task *dt = &t->dept_task; + int i; + + if (unlikely(!dept_working())) + return; + + raw_local_irq_disable(); + + if (dt->stack) + put_stack(dt->stack); + + for (i = 0; i < dt->ecxt_held_pos; i++) { + if (dt->ecxt_held[i].class) + put_class(dt->ecxt_held[i].class); + if (dt->ecxt_held[i].ecxt) + put_ecxt(dt->ecxt_held[i].ecxt); + } + + for (i = 0; i < DEPT_MAX_WAIT_HIST; i++) + if (dt->wait_hist[i].wait) + put_wait(dt->wait_hist[i].wait); + + dt->task_exit = true; + dept_off(); + + raw_local_irq_enable(); +} + +void dept_task_init(struct task_struct *t) +{ + memset(&t->dept_task, 0x0, sizeof(struct dept_task)); +} + +void dept_key_init(struct dept_key *k) +{ + struct dept_task *dt = dept_task(); + unsigned long flags; + int sub_id; + + if (unlikely(!dept_working())) + return; + + if (dt->recursive) { + DEPT_STOP("Key initialization fails.\n"); + return; + } + + flags = dept_enter(); + + clean_classes_cache(k); + + /* + * dept_key_init() should not fail. + * + * FIXME: Should be fixed if dept_key_init() causes deadlock + * with dept_lock(). + */ + while (unlikely(!dept_lock())) + cpu_relax(); + + for (sub_id = 0; sub_id < DEPT_MAX_SUBCLASSES; sub_id++) { + struct dept_class *c; + + c = lookup_class((unsigned long)k->base + sub_id); + if (!c) + continue; + + DEPT_STOP("The class(%s/%d) has not been removed.\n", + c->name, sub_id); + break; + } + + dept_unlock(); + dept_exit(flags); +} +EXPORT_SYMBOL_GPL(dept_key_init); + +void dept_key_destroy(struct dept_key *k) +{ + struct dept_task *dt = dept_task(); + unsigned long flags; + int sub_id; + + if (unlikely(!dept_working())) + return; + + if (dt->recursive == 1 && dt->task_exit) { + /* + * Need to allow to go ahead in this case where + * ->recursive has been set to 1 by dept_off() in + * dept_task_exit() and ->task_exit has been set to + * true in dept_task_exit(). + */ + } else if (dt->recursive) { + DEPT_STOP("Key destroying fails.\n"); + return; + } + + flags = dept_enter(); + + /* + * dept_key_destroy() should not fail. + * + * FIXME: Should be fixed if dept_key_destroy() causes deadlock + * with dept_lock(). + */ + while (unlikely(!dept_lock())) + cpu_relax(); + + for (sub_id = 0; sub_id < DEPT_MAX_SUBCLASSES; sub_id++) { + struct dept_class *c; + + c = lookup_class((unsigned long)k->base + sub_id); + if (!c) + continue; + + hash_del_class(c); + disconnect_class(c); + list_del(&c->all_node); + invalidate_class(c); + + /* + * Actual deletion will happen on the rcu callback + * that has been added in disconnect_class(). + */ + del_class(c); + } + + dept_unlock(); + dept_exit(flags); + + /* + * Wait until even lockless hash_lookup_class() for the class + * returns NULL. + */ + might_sleep(); + synchronize_rcu(); +} +EXPORT_SYMBOL_GPL(dept_key_destroy); + +static void move_llist(struct llist_head *to, struct llist_head *from) +{ + struct llist_node *first = llist_del_all(from); + struct llist_node *last; + + if (!first) + return; + + for (last = first; last->next; last = last->next); + llist_add_batch(first, last, to); +} + +static void migrate_per_cpu_pool(void) +{ + const int boot_cpu = 0; + int i; + + /* + * The boot CPU has been using the temperal local pool so far. + * From now on that per_cpu areas have been ready, use the + * per_cpu local pool instead. + */ + DEPT_WARN_ON(smp_processor_id() != boot_cpu); + for (i = 0; i < OBJECT_NR; i++) { + struct llist_head *from; + struct llist_head *to; + + from = &pool[i].boot_pool; + to = per_cpu_ptr(pool[i].lpool, boot_cpu); + move_llist(to, from); + } +} + +#define B2KB(B) ((B) / 1024) + +/* + * Should be called after setup_per_cpu_areas() and before no non-boot + * CPUs have been on. + */ +void __init dept_init(void) +{ + size_t mem_total = 0; + + local_irq_disable(); + dept_per_cpu_ready = 1; + migrate_per_cpu_pool(); + local_irq_enable(); + +#define OBJECT(id, nr) mem_total += sizeof(struct dept_##id) * nr; + #include "dept_object.h" +#undef OBJECT +#define HASH(id, bits) mem_total += sizeof(struct hlist_head) * (1UL << bits); + #include "dept_hash.h" +#undef HASH + + pr_info("DEPendency Tracker: Copyright (c) 2020 LG Electronics, Inc., Byungchul Park\n"); + pr_info("... DEPT_MAX_STACK_ENTRY: %d\n", DEPT_MAX_STACK_ENTRY); + pr_info("... DEPT_MAX_WAIT_HIST : %d\n", DEPT_MAX_WAIT_HIST); + pr_info("... DEPT_MAX_ECXT_HELD : %d\n", DEPT_MAX_ECXT_HELD); + pr_info("... DEPT_MAX_SUBCLASSES : %d\n", DEPT_MAX_SUBCLASSES); +#define OBJECT(id, nr) \ + pr_info("... memory used by %s: %zu KB\n", \ + #id, B2KB(sizeof(struct dept_##id) * nr)); + #include "dept_object.h" +#undef OBJECT +#define HASH(id, bits) \ + pr_info("... hash list head used by %s: %zu KB\n", \ + #id, B2KB(sizeof(struct hlist_head) * (1UL << bits))); + #include "dept_hash.h" +#undef HASH + pr_info("... total memory used by objects and hashs: %zu KB\n", B2KB(mem_total)); + pr_info("... per task memory footprint: %zu bytes\n", sizeof(struct dept_task)); +} diff --git a/kernel/dependency/dept_hash.h b/kernel/dependency/dept_hash.h new file mode 100644 index 00000000000000..fd85aab1fdfbe0 --- /dev/null +++ b/kernel/dependency/dept_hash.h @@ -0,0 +1,10 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * HASH(id, bits) + * + * id : Id for the object of struct dept_##id. + * bits: 1UL << bits is the hash table size. + */ + +HASH(dep, 12) +HASH(class, 12) diff --git a/kernel/dependency/dept_object.h b/kernel/dependency/dept_object.h new file mode 100644 index 00000000000000..0b7eb16fe9fb0b --- /dev/null +++ b/kernel/dependency/dept_object.h @@ -0,0 +1,13 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * OBJECT(id, nr) + * + * id: Id for the object of struct dept_##id. + * nr: # of the object that should be kept in the pool. + */ + +OBJECT(dep, 1024 * 8) +OBJECT(class, 1024 * 8) +OBJECT(stack, 1024 * 32) +OBJECT(ecxt, 1024 * 16) +OBJECT(wait, 1024 * 32) diff --git a/kernel/exit.c b/kernel/exit.c index 15dc2ec80c4672..0f48752c8b4c35 100644 --- a/kernel/exit.c +++ b/kernel/exit.c @@ -916,6 +916,7 @@ void __noreturn do_exit(long code) exit_tasks_rcu_finish(); lockdep_free_task(tsk); + dept_task_exit(tsk); do_task_dead(); } diff --git a/kernel/fork.c b/kernel/fork.c index 9f7fe354189785..1d33fc3868f193 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -97,6 +97,7 @@ #include #include #include +#include #include #include @@ -2219,6 +2220,7 @@ static __latent_entropy struct task_struct *copy_process( #ifdef CONFIG_LOCKDEP lockdep_init_task(p); #endif + dept_task_init(p); #ifdef CONFIG_DEBUG_MUTEXES p->blocked_on = NULL; /* not blocked yet */ diff --git a/kernel/module/main.c b/kernel/module/main.c index 48568a0f5651ce..2882ea2e1b5a06 100644 --- a/kernel/module/main.c +++ b/kernel/module/main.c @@ -1194,6 +1194,7 @@ static void free_module(struct module *mod) /* Free lock-classes; relies on the preceding sync_rcu(). */ lockdep_free_key_range(mod->data_layout.base, mod->data_layout.size); + dept_free_range(mod->data_layout.base, mod->data_layout.size); /* Finally, free the core (containing the module structure) */ module_memfree(mod->core_layout.base); @@ -2893,6 +2894,7 @@ static int load_module(struct load_info *info, const char __user *uargs, free_module: /* Free lock-classes; relies on the preceding sync_rcu() */ lockdep_free_key_range(mod->data_layout.base, mod->data_layout.size); + dept_free_range(mod->data_layout.base, mod->data_layout.size); module_deallocate(mod, info); free_copy: diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 25b582b6ee5f78..0dc066caed9a14 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -64,6 +64,7 @@ #include #include #include +#include #ifdef CONFIG_PREEMPT_DYNAMIC # ifdef CONFIG_GENERIC_ENTRY @@ -4070,6 +4071,7 @@ try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags) int cpu, success = 0; preempt_disable(); + dept_stage_event(p, _RET_IP_); if (p == current) { /* * We're waking current, this means 'p->on_rq' and 'task_cpu(p) @@ -6446,6 +6448,12 @@ static void __sched notrace __schedule(unsigned int sched_mode) rq = cpu_rq(cpu); prev = rq->curr; + prev_state = READ_ONCE(prev->__state); + if (sched_mode != SM_PREEMPT && prev_state & TASK_NORMAL) + dept_request_event_wait_commit(); + + dept_sched_enter(); + schedule_debug(prev, !!sched_mode); if (sched_feat(HRTICK) || sched_feat(HRTICK_DL)) @@ -6560,6 +6568,7 @@ static void __sched notrace __schedule(unsigned int sched_mode) __balance_callbacks(rq); raw_spin_rq_unlock_irq(rq); } + dept_sched_exit(); } void __noreturn do_task_dead(void) diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 881c3f84e88a32..611fd01751a7ec 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -1255,6 +1255,33 @@ config DEBUG_PREEMPT menu "Lock Debugging (spinlocks, mutexes, etc...)" +config DEPT + bool "Dependency tracking (EXPERIMENTAL)" + depends on DEBUG_KERNEL && LOCK_DEBUGGING_SUPPORT + select DEBUG_SPINLOCK + select DEBUG_MUTEXES + select DEBUG_RT_MUTEXES if RT_MUTEXES + select DEBUG_RWSEMS + select DEBUG_WW_MUTEX_SLOWPATH + select DEBUG_LOCK_ALLOC + select TRACE_IRQFLAGS + select STACKTRACE + select FRAME_POINTER if !MIPS && !PPC && !ARM && !S390 && !MICROBLAZE && !ARC && !X86 + select KALLSYMS + select KALLSYMS_ALL + select PROVE_LOCKING + default n + help + Check dependencies between wait and event and report it if + deadlock possibility has been detected. Multiple reports are + allowed if there are more than a single problem. + + This feature is considered EXPERIMENTAL that might produce + false positive reports because new dependencies start to be + tracked, that have never been tracked before. It's worth + noting, to mitigate the impact by the false positives, multi + reporting has been supported. + config LOCK_DEBUGGING_SUPPORT bool depends on TRACE_IRQFLAGS_SUPPORT && STACKTRACE_SUPPORT && LOCKDEP_SUPPORT diff --git a/lib/locking-selftest.c b/lib/locking-selftest.c index 8d24279fad0553..cd89138d62bacb 100644 --- a/lib/locking-selftest.c +++ b/lib/locking-selftest.c @@ -1398,6 +1398,8 @@ static void reset_locks(void) local_irq_disable(); lockdep_free_key_range(&ww_lockdep.acquire_key, 1); lockdep_free_key_range(&ww_lockdep.mutex_key, 1); + dept_free_range(&ww_lockdep.acquire_key, 1); + dept_free_range(&ww_lockdep.mutex_key, 1); I1(A); I1(B); I1(C); I1(D); I1(X1); I1(X2); I1(Y1); I1(Y2); I1(Z1); I1(Z2);