[GIT PULL] core/locking changes for v3.12
From: Ingo Molnar
Date: Tue Sep 03 2013 - 08:16:10 EST
Linus,
Please pull the latest core-locking-for-linus git tree from:
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git core-locking-for-linus
HEAD: 15e71911fcc655508e02f767a3d9b8b138051d2b generic-ipi/locking: Fix misleading smp_call_function_any() description
Main changes:
- another mutex optimization, from Davidlohr Bueso
- improved lglock lockdep tracking, from Michel Lespinasse
- [ assorted smaller updates, improvements, cleanups. ]
Thanks,
Ingo
------------------>
Davidlohr Bueso (2):
mutex: Do not unnecessarily deal with waiters
mutex: Avoid label warning when !CONFIG_MUTEX_SPIN_ON_OWNER
Michel Lespinasse (2):
lockdep: Introduce lock_acquire_exclusive()/shared() helper macros
lglock: Update lockdep annotations to report recursive local locks
Oleg Nesterov (1):
hung_task debugging: Print more info when reporting the problem
Peter Zijlstra (1):
mutex: Fix/document access-once assumption in mutex_can_spin_on_owner()
Xie XiuQi (1):
generic-ipi/locking: Fix misleading smp_call_function_any() description
include/linux/lockdep.h | 92 +++++++++++++------------------------------------
kernel/hung_task.c | 13 ++++---
kernel/lglock.c | 12 +++----
kernel/mutex.c | 43 +++++++++++------------
kernel/smp.c | 2 --
5 files changed, 58 insertions(+), 104 deletions(-)
diff --git a/include/linux/lockdep.h b/include/linux/lockdep.h
index f1e877b..cfc2f11 100644
--- a/include/linux/lockdep.h
+++ b/include/linux/lockdep.h
@@ -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)
{
@@ -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) \
diff --git a/kernel/hung_task.c b/kernel/hung_task.c
index 6df6149..3e97fb1 100644
--- a/kernel/hung_task.c
+++ b/kernel/hung_task.c
@@ -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:
@@ -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);
diff --git a/kernel/lglock.c b/kernel/lglock.c
index 6535a66..86ae2ae 100644
--- a/kernel/lglock.c
+++ b/kernel/lglock.c
@@ -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);
}
@@ -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();
@@ -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);
}
@@ -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();
@@ -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);
@@ -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);
diff --git a/kernel/mutex.c b/kernel/mutex.c
index ff05f4b..98164a5 100644
--- a/kernel/mutex.c
+++ b/kernel/mutex.c
@@ -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
@@ -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;
}
/*
@@ -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) &&
@@ -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
@@ -513,6 +515,10 @@ slowpath:
#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));
@@ -520,9 +526,6 @@ slowpath:
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 (;;) {
@@ -536,7 +539,7 @@ slowpath:
* other waiters:
*/
if (MUTEX_SHOW_NO_WAITER(lock) &&
- (atomic_xchg(&lock->count, -1) == 1))
+ (atomic_xchg(&lock->count, -1) == 1))
break;
/*
@@ -561,24 +564,25 @@ slowpath:
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;
@@ -592,15 +596,8 @@ done:
}
}
- /* 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:
diff --git a/kernel/smp.c b/kernel/smp.c
index fe9f773..b1c9034 100644
--- a/kernel/smp.c
+++ b/kernel/smp.c
@@ -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
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/