Commit 431f288e authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge branch 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull locking fixes from Thomas Gleixner:
 "A set of locking fixes:

   - Address the fallout of the rwsem rework. Missing ACQUIREs and a
     sanity check to prevent a use-after-free

   - Add missing checks for unitialized mutexes when mutex debugging is
     enabled.

   - Remove the bogus code in the generic SMP variant of
     arch_futex_atomic_op_inuser()

   - Fixup the #ifdeffery in lockdep to prevent compile warnings"

* 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  locking/mutex: Test for initialized mutex
  locking/lockdep: Clean up #ifdef checks
  locking/lockdep: Hide unused 'class' variable
  locking/rwsem: Add ACQUIRE comments
  tty/ldsem, locking/rwsem: Add missing ACQUIRE to read_failed sleep loop
  lcoking/rwsem: Add missing ACQUIRE to read_slowpath sleep loop
  locking/rwsem: Add missing ACQUIRE to read_slowpath exit when queue is empty
  locking/rwsem: Don't call owner_on_cpu() on read-owner
  futex: Cleanup generic SMP variant of arch_futex_atomic_op_inuser()
parents 13fbe991 6c11c6e3
......@@ -93,8 +93,7 @@ static void __ldsem_wake_readers(struct ld_semaphore *sem)
list_for_each_entry_safe(waiter, next, &sem->read_wait, list) {
tsk = waiter->task;
smp_mb();
waiter->task = NULL;
smp_store_release(&waiter->task, NULL);
wake_up_process(tsk);
put_task_struct(tsk);
}
......@@ -194,7 +193,7 @@ down_read_failed(struct ld_semaphore *sem, long count, long timeout)
for (;;) {
set_current_state(TASK_UNINTERRUPTIBLE);
if (!waiter.task)
if (!smp_load_acquire(&waiter.task))
break;
if (!timeout)
break;
......
......@@ -118,26 +118,7 @@ futex_atomic_cmpxchg_inatomic(u32 *uval, u32 __user *uaddr,
static inline int
arch_futex_atomic_op_inuser(int op, u32 oparg, int *oval, u32 __user *uaddr)
{
int oldval = 0, ret;
pagefault_disable();
switch (op) {
case FUTEX_OP_SET:
case FUTEX_OP_ADD:
case FUTEX_OP_OR:
case FUTEX_OP_ANDN:
case FUTEX_OP_XOR:
default:
ret = -ENOSYS;
}
pagefault_enable();
if (!ret)
*oval = oldval;
return ret;
return -ENOSYS;
}
static inline int
......
......@@ -448,7 +448,7 @@ static void print_lockdep_off(const char *bug_msg)
unsigned long nr_stack_trace_entries;
#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
#ifdef CONFIG_PROVE_LOCKING
/*
* Stack-trace: tightly packed array of stack backtrace
* addresses. Protected by the graph_lock.
......@@ -491,7 +491,7 @@ unsigned int max_lockdep_depth;
DEFINE_PER_CPU(struct lockdep_stats, lockdep_stats);
#endif
#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
#ifdef CONFIG_PROVE_LOCKING
/*
* Locking printouts:
*/
......@@ -2969,7 +2969,7 @@ static void check_chain_key(struct task_struct *curr)
#endif
}
#if defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING)
#ifdef CONFIG_PROVE_LOCKING
static int mark_lock(struct task_struct *curr, struct held_lock *this,
enum lock_usage_bit new_bit);
......@@ -3608,7 +3608,7 @@ static int mark_lock(struct task_struct *curr, struct held_lock *this,
return ret;
}
#else /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
#else /* CONFIG_PROVE_LOCKING */
static inline int
mark_usage(struct task_struct *curr, struct held_lock *hlock, int check)
......@@ -3627,7 +3627,7 @@ static inline int separate_irq_context(struct task_struct *curr,
return 0;
}
#endif /* defined(CONFIG_TRACE_IRQFLAGS) && defined(CONFIG_PROVE_LOCKING) */
#endif /* CONFIG_PROVE_LOCKING */
/*
* Initialize a lock instance's lock-class mapping info:
......@@ -4321,8 +4321,7 @@ static void __lock_unpin_lock(struct lockdep_map *lock, struct pin_cookie cookie
*/
static void check_flags(unsigned long flags)
{
#if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP) && \
defined(CONFIG_TRACE_IRQFLAGS)
#if defined(CONFIG_PROVE_LOCKING) && defined(CONFIG_DEBUG_LOCKDEP)
if (!debug_locks)
return;
......
......@@ -200,7 +200,6 @@ static void lockdep_stats_debug_show(struct seq_file *m)
static int lockdep_stats_show(struct seq_file *m, void *v)
{
struct lock_class *class;
unsigned long nr_unused = 0, nr_uncategorized = 0,
nr_irq_safe = 0, nr_irq_unsafe = 0,
nr_softirq_safe = 0, nr_softirq_unsafe = 0,
......@@ -211,6 +210,8 @@ static int lockdep_stats_show(struct seq_file *m, void *v)
sum_forward_deps = 0;
#ifdef CONFIG_PROVE_LOCKING
struct lock_class *class;
list_for_each_entry(class, &all_lock_classes, lock_entry) {
if (class->usage_mask == 0)
......
......@@ -908,6 +908,10 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass,
might_sleep();
#ifdef CONFIG_DEBUG_MUTEXES
DEBUG_LOCKS_WARN_ON(lock->magic != lock);
#endif
ww = container_of(lock, struct ww_mutex, base);
if (use_ww_ctx && ww_ctx) {
if (unlikely(ww_ctx == READ_ONCE(ww->ctx)))
......@@ -1379,8 +1383,13 @@ __ww_mutex_lock_interruptible_slowpath(struct ww_mutex *lock,
*/
int __sched mutex_trylock(struct mutex *lock)
{
bool locked = __mutex_trylock(lock);
bool locked;
#ifdef CONFIG_DEBUG_MUTEXES
DEBUG_LOCKS_WARN_ON(lock->magic != lock);
#endif
locked = __mutex_trylock(lock);
if (locked)
mutex_acquire(&lock->dep_map, 0, 1, _RET_IP_);
......
......@@ -666,7 +666,11 @@ static inline bool rwsem_can_spin_on_owner(struct rw_semaphore *sem,
preempt_disable();
rcu_read_lock();
owner = rwsem_owner_flags(sem, &flags);
if ((flags & nonspinnable) || (owner && !owner_on_cpu(owner)))
/*
* Don't check the read-owner as the entry may be stale.
*/
if ((flags & nonspinnable) ||
(owner && !(flags & RWSEM_READER_OWNED) && !owner_on_cpu(owner)))
ret = false;
rcu_read_unlock();
preempt_enable();
......@@ -1000,6 +1004,7 @@ rwsem_down_read_slowpath(struct rw_semaphore *sem, int state)
atomic_long_add(-RWSEM_READER_BIAS, &sem->count);
adjustment = 0;
if (rwsem_optimistic_spin(sem, false)) {
/* rwsem_optimistic_spin() implies ACQUIRE on success */
/*
* Wake up other readers in the wait list if the front
* waiter is a reader.
......@@ -1014,6 +1019,7 @@ rwsem_down_read_slowpath(struct rw_semaphore *sem, int state)
}
return sem;
} else if (rwsem_reader_phase_trylock(sem, waiter.last_rowner)) {
/* rwsem_reader_phase_trylock() implies ACQUIRE on success */
return sem;
}
......@@ -1032,6 +1038,8 @@ queue:
*/
if (adjustment && !(atomic_long_read(&sem->count) &
(RWSEM_WRITER_MASK | RWSEM_FLAG_HANDOFF))) {
/* Provide lock ACQUIRE */
smp_acquire__after_ctrl_dep();
raw_spin_unlock_irq(&sem->wait_lock);
rwsem_set_reader_owned(sem);
lockevent_inc(rwsem_rlock_fast);
......@@ -1065,15 +1073,18 @@ queue:
wake_up_q(&wake_q);
/* wait to be given the lock */
while (true) {
for (;;) {
set_current_state(state);
if (!waiter.task)
if (!smp_load_acquire(&waiter.task)) {
/* Matches rwsem_mark_wake()'s smp_store_release(). */
break;
}
if (signal_pending_state(state, current)) {
raw_spin_lock_irq(&sem->wait_lock);
if (waiter.task)
goto out_nolock;
raw_spin_unlock_irq(&sem->wait_lock);
/* Ordered by sem->wait_lock against rwsem_mark_wake(). */
break;
}
schedule();
......@@ -1083,6 +1094,7 @@ queue:
__set_current_state(TASK_RUNNING);
lockevent_inc(rwsem_rlock);
return sem;
out_nolock:
list_del(&waiter.list);
if (list_empty(&sem->wait_list)) {
......@@ -1123,8 +1135,10 @@ rwsem_down_write_slowpath(struct rw_semaphore *sem, int state)
/* do optimistic spinning and steal lock if possible */
if (rwsem_can_spin_on_owner(sem, RWSEM_WR_NONSPINNABLE) &&
rwsem_optimistic_spin(sem, true))
rwsem_optimistic_spin(sem, true)) {
/* rwsem_optimistic_spin() implies ACQUIRE on success */
return sem;
}
/*
* Disable reader optimistic spinning for this rwsem after
......@@ -1184,9 +1198,11 @@ rwsem_down_write_slowpath(struct rw_semaphore *sem, int state)
wait:
/* wait until we successfully acquire the lock */
set_current_state(state);
while (true) {
if (rwsem_try_write_lock(sem, wstate))
for (;;) {
if (rwsem_try_write_lock(sem, wstate)) {
/* rwsem_try_write_lock() implies ACQUIRE on success */
break;
}
raw_spin_unlock_irq(&sem->wait_lock);
......
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