futex*: remove FUTEX_WAIT_MULTIPLE operation and futex2 patchset

Signed-off-by: Alexandre Frade <kernel@xanmod.org>
xanmod · Oct 2, 2021 · 12aea22 · 12aea22
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commit 12aea22
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Showing 29 changed files with 113 additions and 1,845 deletions.
diff --git a/Documentation/locking/futex2.rst b/Documentation/locking/futex2.rst
diff --git a/Documentation/locking/index.rst b/Documentation/locking/index.rst
@@ -24,7 +24,6 @@ locking
     percpu-rw-semaphore
     robust-futexes
     robust-futex-ABI
-    futex2
 
 .. only::  subproject and html
 

diff --git a/arch/x86/entry/syscalls/syscall_32.tbl b/arch/x86/entry/syscalls/syscall_32.tbl
@@ -452,6 +452,3 @@
 445	i386	landlock_add_rule	sys_landlock_add_rule
 446	i386	landlock_restrict_self	sys_landlock_restrict_self
 447	i386	memfd_secret		sys_memfd_secret
-448	i386	futex_wait		sys_futex_wait			compat_sys_futex_wait
-449	i386	futex_wake		sys_futex_wake
-450	i386	futex_waitv		sys_futex_waitv			compat_sys_futex_waitv
diff --git a/arch/x86/entry/syscalls/syscall_64.tbl b/arch/x86/entry/syscalls/syscall_64.tbl
@@ -369,9 +369,6 @@
 445	common	landlock_add_rule	sys_landlock_add_rule
 446	common	landlock_restrict_self	sys_landlock_restrict_self
 447	common	memfd_secret		sys_memfd_secret
-448	common	futex_wait		sys_futex_wait
-449	common	futex_wake		sys_futex_wake
-450	common	futex_waitv		sys_futex_waitv
 
 #
 # Due to a historical design error, certain syscalls are numbered differently

diff --git a/include/linux/compat.h b/include/linux/compat.h
@@ -368,12 +368,6 @@ struct compat_robust_list_head {
 	compat_uptr_t			list_op_pending;
 };
 
-struct compat_futex_waitv {
-	compat_uptr_t uaddr;
-	compat_uint_t val;
-	compat_uint_t flags;
-};
-
 #ifdef CONFIG_COMPAT_OLD_SIGACTION
 struct compat_old_sigaction {
 	compat_uptr_t			sa_handler;
@@ -696,10 +690,6 @@ asmlinkage long
 compat_sys_get_robust_list(int pid, compat_uptr_t __user *head_ptr,
 			   compat_size_t __user *len_ptr);
 
-
-asmlinkage long compat_sys_futex_waitv(struct compat_futex_waitv *waiters,
-				       compat_uint_t nr_futexes, compat_uint_t flags,
-				       struct __kernel_timespec __user *timo);
 /* kernel/itimer.c */
 asmlinkage long compat_sys_getitimer(int which,
 				     struct old_itimerval32 __user *it);

diff --git a/include/linux/futex.h b/include/linux/futex.h
@@ -50,49 +50,6 @@ union futex_key {
 	} both;
 };
 
-/**
- * struct futex_q - The hashed futex queue entry, one per waiting task
- * @list:		priority-sorted list of tasks waiting on this futex
- * @task:		the task waiting on the futex
- * @lock_ptr:		the hash bucket lock
- * @key:		the key the futex is hashed on
- * @pi_state:		optional priority inheritance state
- * @rt_waiter:		rt_waiter storage for use with requeue_pi
- * @requeue_pi_key:	the requeue_pi target futex key
- * @bitset:		bitset for the optional bitmasked wakeup
- * @uaddr:		userspace address of futex
- * @uval:		expected futex's value
- *
- * We use this hashed waitqueue, instead of a normal wait_queue_entry_t, so
- * we can wake only the relevant ones (hashed queues may be shared).
- *
- * A futex_q has a woken state, just like tasks have TASK_RUNNING.
- * It is considered woken when plist_node_empty(&q->list) || q->lock_ptr == 0.
- * The order of wakeup is always to make the first condition true, then
- * the second.
- *
- * PI futexes are typically woken before they are removed from the hash list via
- * the rt_mutex code. See unqueue_me_pi().
- */
-struct futex_q {
-	struct plist_node list;
-
-	struct task_struct *task;
-	spinlock_t *lock_ptr;
-	union futex_key key;
-	struct futex_pi_state *pi_state;
-	struct rt_mutex_waiter *rt_waiter;
-	union futex_key *requeue_pi_key;
-	u32 bitset;
-	u32 __user *uaddr;
-	u32 uval;
-} __randomize_layout;
-
-struct futex_vector {
-	struct futex_waitv w;
-	struct futex_q q;
-};
-
 #define FUTEX_KEY_INIT (union futex_key) { .both = { .ptr = 0ULL } }
 
 #ifdef CONFIG_FUTEX
@@ -120,67 +77,6 @@ void futex_exec_release(struct task_struct *tsk);
 
 long do_futex(u32 __user *uaddr, int op, u32 val, ktime_t *timeout,
 	      u32 __user *uaddr2, u32 val2, u32 val3);
-
-int futex_wake(u32 __user *uaddr, unsigned int flags, int nr_wake, u32 bitset);
-
-int futex_wait(u32 __user *uaddr, unsigned int flags, u32 val, ktime_t *abs_time,
-	       u32 bitset);
-
-/*
- * Futex flags used to encode options to functions and preserve them across
- * restarts.
- */
-#ifdef CONFIG_MMU
-# define FLAGS_SHARED		0x01
-#else
-/*
- * NOMMU does not have per process address space. Let the compiler optimize
- * code away.
- */
-# define FLAGS_SHARED		0x00
-#endif
-#define FLAGS_CLOCKRT		0x02
-#define FLAGS_HAS_TIMEOUT	0x04
-
-/*
- * Hash buckets are shared by all the futex_keys that hash to the same
- * location.  Each key may have multiple futex_q structures, one for each task
- * waiting on a futex.
- */
-struct futex_hash_bucket {
-	atomic_t waiters;
-	spinlock_t lock;
-	struct plist_head chain;
-} ____cacheline_aligned_in_smp;
-
-void queue_me(struct futex_q *q, struct futex_hash_bucket *hb);
-
-int unqueue_me(struct futex_q *q);
-
-enum futex_access {
-	FUTEX_READ,
-	FUTEX_WRITE
-};
-
-int get_futex_key(u32 __user *uaddr, bool fshared, union futex_key *key,
-			 enum futex_access rw);
-
-struct futex_hash_bucket *queue_lock(struct futex_q *q);
-
-struct hrtimer_sleeper *futex_setup_timer(ktime_t *time,
-					  struct hrtimer_sleeper *timeout,
-					  int flags, u64 range_ns);
-
-void queue_unlock(struct futex_hash_bucket *hb);
-
-int get_futex_value_locked(u32 *dest, u32 __user *from);
-
-static const struct futex_q futex_q_init = {
-	/* list gets initialized in queue_me()*/
-	.key = FUTEX_KEY_INIT,
-	.bitset = FUTEX_BITSET_MATCH_ANY
-};
-
 #else
 static inline void futex_init_task(struct task_struct *tsk) { }
 static inline void futex_exit_recursive(struct task_struct *tsk) { }

diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
@@ -623,12 +623,6 @@ asmlinkage long sys_get_robust_list(int pid,
 asmlinkage long sys_set_robust_list(struct robust_list_head __user *head,
 				    size_t len);
 
-/* kernel/futex2.c */
-asmlinkage long sys_futex_wait(void __user *uaddr, u64 val, unsigned int flags,
-			       struct __kernel_timespec __user *timo);
-asmlinkage long sys_futex_wake(void __user *uaddr, unsigned int nr_wake,
-			       unsigned int flags);
-
 /* kernel/hrtimer.c */
 asmlinkage long sys_nanosleep(struct __kernel_timespec __user *rqtp,
 			      struct __kernel_timespec __user *rmtp);

diff --git a/include/uapi/asm-generic/unistd.h b/include/uapi/asm-generic/unistd.h
@@ -878,15 +878,8 @@ __SYSCALL(__NR_landlock_restrict_self, sys_landlock_restrict_self)
 __SYSCALL(__NR_memfd_secret, sys_memfd_secret)
 #endif
 
-#define __NR_futex_wait 448
-__SC_COMP(__NR_futex_wait, sys_futex_wait, compat_sys_futex_wait)
-#define __NR_futex_wake 449
-__SYSCALL(__NR_futex_wake, sys_futex_wake)
-#define __NR_futex_wait 450
-__SC_COMP(__NR_futex_waitv, sys_futex_waitv, compat_sys_futex_waitv)
-
 #undef __NR_syscalls
-#define __NR_syscalls 451
+#define __NR_syscalls 448
 
 /*
  * 32 bit systems traditionally used different