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

Pull core/locking changes from Ingo Molnar:
 "Main changes:

   - another mutex optimization, from Davidlohr Bueso

   - improved lglock lockdep tracking, from Michel Lespinasse

   - [ assorted smaller updates, improvements, cleanups. ]"

* 'core-locking-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  generic-ipi/locking: Fix misleading smp_call_function_any() description
  hung_task debugging: Print more info when reporting the problem
  mutex: Avoid label warning when !CONFIG_MUTEX_SPIN_ON_OWNER
  mutex: Do not unnecessarily deal with waiters
  mutex: Fix/document access-once assumption in mutex_can_spin_on_owner()
  lglock: Update lockdep annotations to report recursive local locks
  lockdep: Introduce lock_acquire_exclusive()/shared() helper macros
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Linus Torvalds committed Sep 4, 2013
2 parents b854e4d + 15e7191 commit 4689550
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Showing 5 changed files with 58 additions and 104 deletions.
92 changes: 23 additions & 69 deletions include/linux/lockdep.h
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Original file line number Diff line number Diff line change
Expand Up @@ -365,7 +365,7 @@ extern void lockdep_trace_alloc(gfp_t mask);

#define lockdep_recursing(tsk) ((tsk)->lockdep_recursion)

#else /* !LOCKDEP */
#else /* !CONFIG_LOCKDEP */

static inline void lockdep_off(void)
{
Expand Down Expand Up @@ -479,82 +479,36 @@ static inline void print_irqtrace_events(struct task_struct *curr)
* on the per lock-class debug mode:
*/

#ifdef CONFIG_DEBUG_LOCK_ALLOC
# ifdef CONFIG_PROVE_LOCKING
# define spin_acquire(l, s, t, i) lock_acquire(l, s, t, 0, 2, NULL, i)
# define spin_acquire_nest(l, s, t, n, i) lock_acquire(l, s, t, 0, 2, n, i)
# else
# define spin_acquire(l, s, t, i) lock_acquire(l, s, t, 0, 1, NULL, i)
# define spin_acquire_nest(l, s, t, n, i) lock_acquire(l, s, t, 0, 1, NULL, i)
# endif
# define spin_release(l, n, i) lock_release(l, n, i)
#ifdef CONFIG_PROVE_LOCKING
#define lock_acquire_exclusive(l, s, t, n, i) lock_acquire(l, s, t, 0, 2, n, i)
#define lock_acquire_shared(l, s, t, n, i) lock_acquire(l, s, t, 1, 2, n, i)
#define lock_acquire_shared_recursive(l, s, t, n, i) lock_acquire(l, s, t, 2, 2, n, i)
#else
# define spin_acquire(l, s, t, i) do { } while (0)
# define spin_release(l, n, i) do { } while (0)
#define lock_acquire_exclusive(l, s, t, n, i) lock_acquire(l, s, t, 0, 1, n, i)
#define lock_acquire_shared(l, s, t, n, i) lock_acquire(l, s, t, 1, 1, n, i)
#define lock_acquire_shared_recursive(l, s, t, n, i) lock_acquire(l, s, t, 2, 1, n, i)
#endif

#ifdef CONFIG_DEBUG_LOCK_ALLOC
# ifdef CONFIG_PROVE_LOCKING
# define rwlock_acquire(l, s, t, i) lock_acquire(l, s, t, 0, 2, NULL, i)
# define rwlock_acquire_read(l, s, t, i) lock_acquire(l, s, t, 2, 2, NULL, i)
# else
# define rwlock_acquire(l, s, t, i) lock_acquire(l, s, t, 0, 1, NULL, i)
# define rwlock_acquire_read(l, s, t, i) lock_acquire(l, s, t, 2, 1, NULL, i)
# endif
# define rwlock_release(l, n, i) lock_release(l, n, i)
#else
# define rwlock_acquire(l, s, t, i) do { } while (0)
# define rwlock_acquire_read(l, s, t, i) do { } while (0)
# define rwlock_release(l, n, i) do { } while (0)
#endif
#define spin_acquire(l, s, t, i) lock_acquire_exclusive(l, s, t, NULL, i)
#define spin_acquire_nest(l, s, t, n, i) lock_acquire_exclusive(l, s, t, n, i)
#define spin_release(l, n, i) lock_release(l, n, i)

#ifdef CONFIG_DEBUG_LOCK_ALLOC
# ifdef CONFIG_PROVE_LOCKING
# define mutex_acquire(l, s, t, i) lock_acquire(l, s, t, 0, 2, NULL, i)
# define mutex_acquire_nest(l, s, t, n, i) lock_acquire(l, s, t, 0, 2, n, i)
# else
# define mutex_acquire(l, s, t, i) lock_acquire(l, s, t, 0, 1, NULL, i)
# define mutex_acquire_nest(l, s, t, n, i) lock_acquire(l, s, t, 0, 1, n, i)
# endif
# define mutex_release(l, n, i) lock_release(l, n, i)
#else
# define mutex_acquire(l, s, t, i) do { } while (0)
# define mutex_acquire_nest(l, s, t, n, i) do { } while (0)
# define mutex_release(l, n, i) do { } while (0)
#endif
#define rwlock_acquire(l, s, t, i) lock_acquire_exclusive(l, s, t, NULL, i)
#define rwlock_acquire_read(l, s, t, i) lock_acquire_shared_recursive(l, s, t, NULL, i)
#define rwlock_release(l, n, i) lock_release(l, n, i)

#ifdef CONFIG_DEBUG_LOCK_ALLOC
# ifdef CONFIG_PROVE_LOCKING
# define rwsem_acquire(l, s, t, i) lock_acquire(l, s, t, 0, 2, NULL, i)
# define rwsem_acquire_nest(l, s, t, n, i) lock_acquire(l, s, t, 0, 2, n, i)
# define rwsem_acquire_read(l, s, t, i) lock_acquire(l, s, t, 1, 2, NULL, i)
# else
# define rwsem_acquire(l, s, t, i) lock_acquire(l, s, t, 0, 1, NULL, i)
# define rwsem_acquire_nest(l, s, t, n, i) lock_acquire(l, s, t, 0, 1, n, i)
# define rwsem_acquire_read(l, s, t, i) lock_acquire(l, s, t, 1, 1, NULL, i)
# endif
#define mutex_acquire(l, s, t, i) lock_acquire_exclusive(l, s, t, NULL, i)
#define mutex_acquire_nest(l, s, t, n, i) lock_acquire_exclusive(l, s, t, n, i)
#define mutex_release(l, n, i) lock_release(l, n, i)

#define rwsem_acquire(l, s, t, i) lock_acquire_exclusive(l, s, t, NULL, i)
#define rwsem_acquire_nest(l, s, t, n, i) lock_acquire_exclusive(l, s, t, n, i)
#define rwsem_acquire_read(l, s, t, i) lock_acquire_shared(l, s, t, NULL, i)
# define rwsem_release(l, n, i) lock_release(l, n, i)
#else
# define rwsem_acquire(l, s, t, i) do { } while (0)
# define rwsem_acquire_nest(l, s, t, n, i) do { } while (0)
# define rwsem_acquire_read(l, s, t, i) do { } while (0)
# define rwsem_release(l, n, i) do { } while (0)
#endif

#ifdef CONFIG_DEBUG_LOCK_ALLOC
# ifdef CONFIG_PROVE_LOCKING
# define lock_map_acquire(l) lock_acquire(l, 0, 0, 0, 2, NULL, _THIS_IP_)
# define lock_map_acquire_read(l) lock_acquire(l, 0, 0, 2, 2, NULL, _THIS_IP_)
# else
# define lock_map_acquire(l) lock_acquire(l, 0, 0, 0, 1, NULL, _THIS_IP_)
# define lock_map_acquire_read(l) lock_acquire(l, 0, 0, 2, 1, NULL, _THIS_IP_)
# endif
#define lock_map_acquire(l) lock_acquire_exclusive(l, 0, 0, NULL, _THIS_IP_)
#define lock_map_acquire_read(l) lock_acquire_shared_recursive(l, 0, 0, NULL, _THIS_IP_)
# define lock_map_release(l) lock_release(l, 1, _THIS_IP_)
#else
# define lock_map_acquire(l) do { } while (0)
# define lock_map_acquire_read(l) do { } while (0)
# define lock_map_release(l) do { } while (0)
#endif

#ifdef CONFIG_PROVE_LOCKING
# define might_lock(lock) \
Expand Down
13 changes: 9 additions & 4 deletions kernel/hung_task.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -15,6 +15,7 @@
#include <linux/lockdep.h>
#include <linux/export.h>
#include <linux/sysctl.h>
#include <linux/utsname.h>

/*
* The number of tasks checked:
Expand Down Expand Up @@ -99,10 +100,14 @@ static void check_hung_task(struct task_struct *t, unsigned long timeout)
* Ok, the task did not get scheduled for more than 2 minutes,
* complain:
*/
printk(KERN_ERR "INFO: task %s:%d blocked for more than "
"%ld seconds.\n", t->comm, t->pid, timeout);
printk(KERN_ERR "\"echo 0 > /proc/sys/kernel/hung_task_timeout_secs\""
" disables this message.\n");
pr_err("INFO: task %s:%d blocked for more than %ld seconds.\n",
t->comm, t->pid, timeout);
pr_err(" %s %s %.*s\n",
print_tainted(), init_utsname()->release,
(int)strcspn(init_utsname()->version, " "),
init_utsname()->version);
pr_err("\"echo 0 > /proc/sys/kernel/hung_task_timeout_secs\""
" disables this message.\n");
sched_show_task(t);
debug_show_held_locks(t);

Expand Down
12 changes: 6 additions & 6 deletions kernel/lglock.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -21,7 +21,7 @@ void lg_local_lock(struct lglock *lg)
arch_spinlock_t *lock;

preempt_disable();
rwlock_acquire_read(&lg->lock_dep_map, 0, 0, _RET_IP_);
lock_acquire_shared(&lg->lock_dep_map, 0, 0, NULL, _RET_IP_);
lock = this_cpu_ptr(lg->lock);
arch_spin_lock(lock);
}
Expand All @@ -31,7 +31,7 @@ void lg_local_unlock(struct lglock *lg)
{
arch_spinlock_t *lock;

rwlock_release(&lg->lock_dep_map, 1, _RET_IP_);
lock_release(&lg->lock_dep_map, 1, _RET_IP_);
lock = this_cpu_ptr(lg->lock);
arch_spin_unlock(lock);
preempt_enable();
Expand All @@ -43,7 +43,7 @@ void lg_local_lock_cpu(struct lglock *lg, int cpu)
arch_spinlock_t *lock;

preempt_disable();
rwlock_acquire_read(&lg->lock_dep_map, 0, 0, _RET_IP_);
lock_acquire_shared(&lg->lock_dep_map, 0, 0, NULL, _RET_IP_);
lock = per_cpu_ptr(lg->lock, cpu);
arch_spin_lock(lock);
}
Expand All @@ -53,7 +53,7 @@ void lg_local_unlock_cpu(struct lglock *lg, int cpu)
{
arch_spinlock_t *lock;

rwlock_release(&lg->lock_dep_map, 1, _RET_IP_);
lock_release(&lg->lock_dep_map, 1, _RET_IP_);
lock = per_cpu_ptr(lg->lock, cpu);
arch_spin_unlock(lock);
preempt_enable();
Expand All @@ -65,7 +65,7 @@ void lg_global_lock(struct lglock *lg)
int i;

preempt_disable();
rwlock_acquire(&lg->lock_dep_map, 0, 0, _RET_IP_);
lock_acquire_exclusive(&lg->lock_dep_map, 0, 0, NULL, _RET_IP_);
for_each_possible_cpu(i) {
arch_spinlock_t *lock;
lock = per_cpu_ptr(lg->lock, i);
Expand All @@ -78,7 +78,7 @@ void lg_global_unlock(struct lglock *lg)
{
int i;

rwlock_release(&lg->lock_dep_map, 1, _RET_IP_);
lock_release(&lg->lock_dep_map, 1, _RET_IP_);
for_each_possible_cpu(i) {
arch_spinlock_t *lock;
lock = per_cpu_ptr(lg->lock, i);
Expand Down
43 changes: 20 additions & 23 deletions kernel/mutex.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -209,11 +209,13 @@ int mutex_spin_on_owner(struct mutex *lock, struct task_struct *owner)
*/
static inline int mutex_can_spin_on_owner(struct mutex *lock)
{
struct task_struct *owner;
int retval = 1;

rcu_read_lock();
if (lock->owner)
retval = lock->owner->on_cpu;
owner = ACCESS_ONCE(lock->owner);
if (owner)
retval = owner->on_cpu;
rcu_read_unlock();
/*
* if lock->owner is not set, the mutex owner may have just acquired
Expand Down Expand Up @@ -461,7 +463,7 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass,
* performed the optimistic spinning cannot be done.
*/
if (ACCESS_ONCE(ww->ctx))
break;
goto slowpath;
}

/*
Expand All @@ -472,7 +474,7 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass,
owner = ACCESS_ONCE(lock->owner);
if (owner && !mutex_spin_on_owner(lock, owner)) {
mspin_unlock(MLOCK(lock), &node);
break;
goto slowpath;
}

if ((atomic_read(&lock->count) == 1) &&
Expand All @@ -499,7 +501,7 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass,
* the owner complete.
*/
if (!owner && (need_resched() || rt_task(task)))
break;
goto slowpath;

/*
* The cpu_relax() call is a compiler barrier which forces
Expand All @@ -513,16 +515,17 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass,
#endif
spin_lock_mutex(&lock->wait_lock, flags);

/* once more, can we acquire the lock? */
if (MUTEX_SHOW_NO_WAITER(lock) && (atomic_xchg(&lock->count, 0) == 1))
goto skip_wait;

debug_mutex_lock_common(lock, &waiter);
debug_mutex_add_waiter(lock, &waiter, task_thread_info(task));

/* add waiting tasks to the end of the waitqueue (FIFO): */
list_add_tail(&waiter.list, &lock->wait_list);
waiter.task = task;

if (MUTEX_SHOW_NO_WAITER(lock) && (atomic_xchg(&lock->count, -1) == 1))
goto done;

lock_contended(&lock->dep_map, ip);

for (;;) {
Expand All @@ -536,7 +539,7 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass,
* other waiters:
*/
if (MUTEX_SHOW_NO_WAITER(lock) &&
(atomic_xchg(&lock->count, -1) == 1))
(atomic_xchg(&lock->count, -1) == 1))
break;

/*
Expand All @@ -561,24 +564,25 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass,
schedule_preempt_disabled();
spin_lock_mutex(&lock->wait_lock, flags);
}
mutex_remove_waiter(lock, &waiter, current_thread_info());
/* set it to 0 if there are no waiters left: */
if (likely(list_empty(&lock->wait_list)))
atomic_set(&lock->count, 0);
debug_mutex_free_waiter(&waiter);

done:
skip_wait:
/* got the lock - cleanup and rejoice! */
lock_acquired(&lock->dep_map, ip);
/* got the lock - rejoice! */
mutex_remove_waiter(lock, &waiter, current_thread_info());
mutex_set_owner(lock);

if (!__builtin_constant_p(ww_ctx == NULL)) {
struct ww_mutex *ww = container_of(lock,
struct ww_mutex,
base);
struct ww_mutex *ww = container_of(lock, struct ww_mutex, base);
struct mutex_waiter *cur;

/*
* This branch gets optimized out for the common case,
* and is only important for ww_mutex_lock.
*/

ww_mutex_lock_acquired(ww, ww_ctx);
ww->ctx = ww_ctx;

Expand All @@ -592,15 +596,8 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass,
}
}

/* set it to 0 if there are no waiters left: */
if (likely(list_empty(&lock->wait_list)))
atomic_set(&lock->count, 0);

spin_unlock_mutex(&lock->wait_lock, flags);

debug_mutex_free_waiter(&waiter);
preempt_enable();

return 0;

err:
Expand Down
2 changes: 0 additions & 2 deletions kernel/smp.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -278,8 +278,6 @@ EXPORT_SYMBOL(smp_call_function_single);
* @wait: If true, wait until function has completed.
*
* Returns 0 on success, else a negative status code (if no cpus were online).
* Note that @wait will be implicitly turned on in case of allocation failures,
* since we fall back to on-stack allocation.
*
* Selection preference:
* 1) current cpu if in @mask
Expand Down

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