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[PATCH] lockdep: better lock debugging

Generic lock debugging:

 - generalized lock debugging framework. For example, a bug in one lock
   subsystem turns off debugging in all lock subsystems.

 - got rid of the caller address passing (__IP__/__IP_DECL__/etc.) from
   the mutex/rtmutex debugging code: it caused way too much prototype
   hackery, and lockdep will give the same information anyway.

 - ability to do silent tests

 - check lock freeing in vfree too.

 - more finegrained debugging options, to allow distributions to
   turn off more expensive debugging features.

There's no separate 'held mutexes' list anymore - but there's a 'held locks'
stack within lockdep, which unifies deadlock detection across all lock
classes.  (this is independent of the lockdep validation stuff - lockdep first
checks whether we are holding a lock already)

Here are the current debugging options:

CONFIG_DEBUG_MUTEXES=y
CONFIG_DEBUG_LOCK_ALLOC=y

which do:

 config DEBUG_MUTEXES
          bool "Mutex debugging, basic checks"

 config DEBUG_LOCK_ALLOC
         bool "Detect incorrect freeing of live mutexes"

Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Arjan van de Ven <arjan@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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1 parent fb7e424 commit 9a11b49a805665e13a56aa067afaf81d43ec1514 Ingo Molnar committed with Linus Torvalds Jul 3, 2006
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@@ -151,7 +151,7 @@ static struct sysrq_key_op sysrq_mountro_op = {
static void sysrq_handle_showlocks(int key, struct pt_regs *pt_regs,
struct tty_struct *tty)
{
- mutex_debug_show_all_locks();
+ debug_show_all_locks();
}
static struct sysrq_key_op sysrq_showlocks_op = {
.handler = sysrq_handle_showlocks,
@@ -10,15 +10,10 @@
#ifndef _ASM_GENERIC_MUTEX_NULL_H
#define _ASM_GENERIC_MUTEX_NULL_H
-/* extra parameter only needed for mutex debugging: */
-#ifndef __IP__
-# define __IP__
-#endif
-
-#define __mutex_fastpath_lock(count, fail_fn) fail_fn(count __RET_IP__)
-#define __mutex_fastpath_lock_retval(count, fail_fn) fail_fn(count __RET_IP__)
-#define __mutex_fastpath_unlock(count, fail_fn) fail_fn(count __RET_IP__)
-#define __mutex_fastpath_trylock(count, fail_fn) fail_fn(count)
-#define __mutex_slowpath_needs_to_unlock() 1
+#define __mutex_fastpath_lock(count, fail_fn) fail_fn(count)
+#define __mutex_fastpath_lock_retval(count, fail_fn) fail_fn(count)
+#define __mutex_fastpath_unlock(count, fail_fn) fail_fn(count)
+#define __mutex_fastpath_trylock(count, fail_fn) fail_fn(count)
+#define __mutex_slowpath_needs_to_unlock() 1
#endif
@@ -0,0 +1,69 @@
+#ifndef __LINUX_DEBUG_LOCKING_H
+#define __LINUX_DEBUG_LOCKING_H
+
+extern int debug_locks;
+extern int debug_locks_silent;
+
+/*
+ * Generic 'turn off all lock debugging' function:
+ */
+extern int debug_locks_off(void);
+
+/*
+ * In the debug case we carry the caller's instruction pointer into
+ * other functions, but we dont want the function argument overhead
+ * in the nondebug case - hence these macros:
+ */
+#define _RET_IP_ (unsigned long)__builtin_return_address(0)
+#define _THIS_IP_ ({ __label__ __here; __here: (unsigned long)&&__here; })
+
+#define DEBUG_LOCKS_WARN_ON(c) \
+({ \
+ int __ret = 0; \
+ \
+ if (unlikely(c)) { \
+ if (debug_locks_off()) \
+ WARN_ON(1); \
+ __ret = 1; \
+ } \
+ __ret; \
+})
+
+#ifdef CONFIG_SMP
+# define SMP_DEBUG_LOCKS_WARN_ON(c) DEBUG_LOCKS_WARN_ON(c)
+#else
+# define SMP_DEBUG_LOCKS_WARN_ON(c) do { } while (0)
+#endif
+
+#ifdef CONFIG_DEBUG_LOCKING_API_SELFTESTS
+ extern void locking_selftest(void);
+#else
+# define locking_selftest() do { } while (0)
+#endif
+
+#ifdef CONFIG_LOCKDEP
+extern void debug_show_all_locks(void);
+extern void debug_show_held_locks(struct task_struct *task);
+extern void debug_check_no_locks_freed(const void *from, unsigned long len);
+extern void debug_check_no_locks_held(struct task_struct *task);
+#else
+static inline void debug_show_all_locks(void)
+{
+}
+
+static inline void debug_show_held_locks(struct task_struct *task)
+{
+}
+
+static inline void
+debug_check_no_locks_freed(const void *from, unsigned long len)
+{
+}
+
+static inline void
+debug_check_no_locks_held(struct task_struct *task)
+{
+}
+#endif
+
+#endif
@@ -124,7 +124,6 @@ extern struct group_info init_groups;
.cpu_timers = INIT_CPU_TIMERS(tsk.cpu_timers), \
.fs_excl = ATOMIC_INIT(0), \
.pi_lock = SPIN_LOCK_UNLOCKED, \
- INIT_RT_MUTEXES(tsk) \
}
View
@@ -14,6 +14,7 @@
#include <linux/prio_tree.h>
#include <linux/fs.h>
#include <linux/mutex.h>
+#include <linux/debug_locks.h>
struct mempolicy;
struct anon_vma;
@@ -1034,13 +1035,6 @@ static inline void vm_stat_account(struct mm_struct *mm,
}
#endif /* CONFIG_PROC_FS */
-static inline void
-debug_check_no_locks_freed(const void *from, unsigned long len)
-{
- mutex_debug_check_no_locks_freed(from, len);
- rt_mutex_debug_check_no_locks_freed(from, len);
-}
-
#ifndef CONFIG_DEBUG_PAGEALLOC
static inline void
kernel_map_pages(struct page *page, int numpages, int enable)
@@ -7,17 +7,11 @@
* Mutexes - debugging helpers:
*/
-#define __DEBUG_MUTEX_INITIALIZER(lockname) \
- , .held_list = LIST_HEAD_INIT(lockname.held_list), \
- .name = #lockname , .magic = &lockname
+#define __DEBUG_MUTEX_INITIALIZER(lockname) \
+ , .magic = &lockname
-#define mutex_init(sem) __mutex_init(sem, __FUNCTION__)
+#define mutex_init(sem) __mutex_init(sem, __FILE__":"#sem)
extern void FASTCALL(mutex_destroy(struct mutex *lock));
-extern void mutex_debug_show_all_locks(void);
-extern void mutex_debug_show_held_locks(struct task_struct *filter);
-extern void mutex_debug_check_no_locks_held(struct task_struct *task);
-extern void mutex_debug_check_no_locks_freed(const void *from, unsigned long len);
-
#endif
View
@@ -50,8 +50,6 @@ struct mutex {
struct list_head wait_list;
#ifdef CONFIG_DEBUG_MUTEXES
struct thread_info *owner;
- struct list_head held_list;
- unsigned long acquire_ip;
const char *name;
void *magic;
#endif
@@ -76,10 +74,6 @@ struct mutex_waiter {
# define __DEBUG_MUTEX_INITIALIZER(lockname)
# define mutex_init(mutex) __mutex_init(mutex, NULL)
# define mutex_destroy(mutex) do { } while (0)
-# define mutex_debug_show_all_locks() do { } while (0)
-# define mutex_debug_show_held_locks(p) do { } while (0)
-# define mutex_debug_check_no_locks_held(task) do { } while (0)
-# define mutex_debug_check_no_locks_freed(from, len) do { } while (0)
#endif
#define __MUTEX_INITIALIZER(lockname) \
View
@@ -29,8 +29,6 @@ struct rt_mutex {
struct task_struct *owner;
#ifdef CONFIG_DEBUG_RT_MUTEXES
int save_state;
- struct list_head held_list_entry;
- unsigned long acquire_ip;
const char *name, *file;
int line;
void *magic;
@@ -98,14 +96,6 @@ extern int rt_mutex_trylock(struct rt_mutex *lock);
extern void rt_mutex_unlock(struct rt_mutex *lock);
-#ifdef CONFIG_DEBUG_RT_MUTEXES
-# define INIT_RT_MUTEX_DEBUG(tsk) \
- .held_list_head = LIST_HEAD_INIT(tsk.held_list_head), \
- .held_list_lock = SPIN_LOCK_UNLOCKED
-#else
-# define INIT_RT_MUTEX_DEBUG(tsk)
-#endif
-
#ifdef CONFIG_RT_MUTEXES
# define INIT_RT_MUTEXES(tsk) \
.pi_waiters = PLIST_HEAD_INIT(tsk.pi_waiters, tsk.pi_lock), \
View
@@ -865,10 +865,6 @@ struct task_struct {
struct plist_head pi_waiters;
/* Deadlock detection and priority inheritance handling */
struct rt_mutex_waiter *pi_blocked_on;
-# ifdef CONFIG_DEBUG_RT_MUTEXES
- spinlock_t held_list_lock;
- struct list_head held_list_head;
-# endif
#endif
#ifdef CONFIG_DEBUG_MUTEXES
View
@@ -47,6 +47,7 @@
#include <linux/key.h>
#include <linux/unwind.h>
#include <linux/buffer_head.h>
+#include <linux/debug_locks.h>
#include <asm/io.h>
#include <asm/bugs.h>
@@ -511,6 +512,13 @@ asmlinkage void __init start_kernel(void)
console_init();
if (panic_later)
panic(panic_later, panic_param);
+ /*
+ * Need to run this when irqs are enabled, because it wants
+ * to self-test [hard/soft]-irqs on/off lock inversion bugs
+ * too:
+ */
+ locking_selftest();
+
#ifdef CONFIG_BLK_DEV_INITRD
if (initrd_start && !initrd_below_start_ok &&
initrd_start < min_low_pfn << PAGE_SHIFT) {
View
@@ -933,10 +933,9 @@ fastcall NORET_TYPE void do_exit(long code)
if (unlikely(current->pi_state_cache))
kfree(current->pi_state_cache);
/*
- * If DEBUG_MUTEXES is on, make sure we are holding no locks:
+ * Make sure we are holding no locks:
*/
- mutex_debug_check_no_locks_held(tsk);
- rt_mutex_debug_check_no_locks_held(tsk);
+ debug_check_no_locks_held(tsk);
if (tsk->io_context)
exit_io_context();
View
@@ -919,10 +919,6 @@ static inline void rt_mutex_init_task(struct task_struct *p)
spin_lock_init(&p->pi_lock);
plist_head_init(&p->pi_waiters, &p->pi_lock);
p->pi_blocked_on = NULL;
-# ifdef CONFIG_DEBUG_RT_MUTEXES
- spin_lock_init(&p->held_list_lock);
- INIT_LIST_HEAD(&p->held_list_head);
-# endif
#endif
}
View
@@ -20,52 +20,19 @@
#include <linux/spinlock.h>
#include <linux/kallsyms.h>
#include <linux/interrupt.h>
+#include <linux/debug_locks.h>
#include "mutex-debug.h"
-/*
- * We need a global lock when we walk through the multi-process
- * lock tree. Only used in the deadlock-debugging case.
- */
-DEFINE_SPINLOCK(debug_mutex_lock);
-
-/*
- * All locks held by all tasks, in a single global list:
- */
-LIST_HEAD(debug_mutex_held_locks);
-
-/*
- * In the debug case we carry the caller's instruction pointer into
- * other functions, but we dont want the function argument overhead
- * in the nondebug case - hence these macros:
- */
-#define __IP_DECL__ , unsigned long ip
-#define __IP__ , ip
-#define __RET_IP__ , (unsigned long)__builtin_return_address(0)
-
-/*
- * "mutex debugging enabled" flag. We turn it off when we detect
- * the first problem because we dont want to recurse back
- * into the tracing code when doing error printk or
- * executing a BUG():
- */
-int debug_mutex_on = 1;
-
/*
* Must be called with lock->wait_lock held.
*/
-void debug_mutex_set_owner(struct mutex *lock,
- struct thread_info *new_owner __IP_DECL__)
+void debug_mutex_set_owner(struct mutex *lock, struct thread_info *new_owner)
{
lock->owner = new_owner;
- DEBUG_LOCKS_WARN_ON(!list_empty(&lock->held_list));
- if (debug_mutex_on) {
- list_add_tail(&lock->held_list, &debug_mutex_held_locks);
- lock->acquire_ip = ip;
- }
}
-void debug_mutex_init_waiter(struct mutex_waiter *waiter)
+void debug_mutex_lock_common(struct mutex *lock, struct mutex_waiter *waiter)
{
memset(waiter, MUTEX_DEBUG_INIT, sizeof(*waiter));
waiter->magic = waiter;
@@ -87,9 +54,10 @@ void debug_mutex_free_waiter(struct mutex_waiter *waiter)
}
void debug_mutex_add_waiter(struct mutex *lock, struct mutex_waiter *waiter,
- struct thread_info *ti __IP_DECL__)
+ struct thread_info *ti)
{
SMP_DEBUG_LOCKS_WARN_ON(!spin_is_locked(&lock->wait_lock));
+
/* Mark the current thread as blocked on the lock: */
ti->task->blocked_on = waiter;
waiter->lock = lock;
@@ -109,24 +77,19 @@ void mutex_remove_waiter(struct mutex *lock, struct mutex_waiter *waiter,
void debug_mutex_unlock(struct mutex *lock)
{
+ DEBUG_LOCKS_WARN_ON(lock->owner != current_thread_info());
DEBUG_LOCKS_WARN_ON(lock->magic != lock);
DEBUG_LOCKS_WARN_ON(!lock->wait_list.prev && !lock->wait_list.next);
DEBUG_LOCKS_WARN_ON(lock->owner != current_thread_info());
- if (debug_mutex_on) {
- DEBUG_LOCKS_WARN_ON(list_empty(&lock->held_list));
- list_del_init(&lock->held_list);
- }
}
void debug_mutex_init(struct mutex *lock, const char *name)
{
/*
* Make sure we are not reinitializing a held lock:
*/
- mutex_debug_check_no_locks_freed((void *)lock, sizeof(*lock));
+ debug_check_no_locks_freed((void *)lock, sizeof(*lock));
lock->owner = NULL;
- INIT_LIST_HEAD(&lock->held_list);
- lock->name = name;
lock->magic = lock;
}
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