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-rw-r--r--kernel/locking/Makefile3
-rw-r--r--kernel/locking/mcs_spinlock.h16
-rw-r--r--kernel/locking/mutex.c60
-rw-r--r--kernel/locking/osq_lock.c (renamed from kernel/locking/mcs_spinlock.c)9
-rw-r--r--kernel/locking/rtmutex.c7
-rw-r--r--kernel/locking/rwsem-spinlock.c2
-rw-r--r--kernel/locking/rwsem-xadd.c3
7 files changed, 41 insertions, 59 deletions
diff --git a/kernel/locking/Makefile b/kernel/locking/Makefile
index 8541bfdfd232..4ca8eb151975 100644
--- a/kernel/locking/Makefile
+++ b/kernel/locking/Makefile
@@ -1,5 +1,5 @@
-obj-y += mutex.o semaphore.o rwsem.o mcs_spinlock.o
+obj-y += mutex.o semaphore.o rwsem.o
ifdef CONFIG_FUNCTION_TRACER
CFLAGS_REMOVE_lockdep.o = -pg
@@ -14,6 +14,7 @@ ifeq ($(CONFIG_PROC_FS),y)
obj-$(CONFIG_LOCKDEP) += lockdep_proc.o
endif
obj-$(CONFIG_SMP) += spinlock.o
+obj-$(CONFIG_LOCK_SPIN_ON_OWNER) += osq_lock.o
obj-$(CONFIG_SMP) += lglock.o
obj-$(CONFIG_PROVE_LOCKING) += spinlock.o
obj-$(CONFIG_RT_MUTEXES) += rtmutex.o
diff --git a/kernel/locking/mcs_spinlock.h b/kernel/locking/mcs_spinlock.h
index 4d60986fcbee..d1fe2ba5bac9 100644
--- a/kernel/locking/mcs_spinlock.h
+++ b/kernel/locking/mcs_spinlock.h
@@ -108,20 +108,4 @@ void mcs_spin_unlock(struct mcs_spinlock **lock, struct mcs_spinlock *node)
arch_mcs_spin_unlock_contended(&next->locked);
}
-/*
- * Cancellable version of the MCS lock above.
- *
- * Intended for adaptive spinning of sleeping locks:
- * mutex_lock()/rwsem_down_{read,write}() etc.
- */
-
-struct optimistic_spin_node {
- struct optimistic_spin_node *next, *prev;
- int locked; /* 1 if lock acquired */
- int cpu; /* encoded CPU # value */
-};
-
-extern bool osq_lock(struct optimistic_spin_queue *lock);
-extern void osq_unlock(struct optimistic_spin_queue *lock);
-
#endif /* __LINUX_MCS_SPINLOCK_H */
diff --git a/kernel/locking/mutex.c b/kernel/locking/mutex.c
index 5b49f652a3cf..94674e5919cb 100644
--- a/kernel/locking/mutex.c
+++ b/kernel/locking/mutex.c
@@ -147,7 +147,7 @@ static __always_inline void ww_mutex_lock_acquired(struct ww_mutex *ww,
}
/*
- * after acquiring lock with fastpath or when we lost out in contested
+ * After acquiring lock with fastpath or when we lost out in contested
* slowpath, set ctx and wake up any waiters so they can recheck.
*
* This function is never called when CONFIG_DEBUG_LOCK_ALLOC is set,
@@ -191,19 +191,32 @@ ww_mutex_set_context_fastpath(struct ww_mutex *lock,
spin_unlock_mutex(&lock->base.wait_lock, flags);
}
-
-#ifdef CONFIG_MUTEX_SPIN_ON_OWNER
/*
- * In order to avoid a stampede of mutex spinners from acquiring the mutex
- * more or less simultaneously, the spinners need to acquire a MCS lock
- * first before spinning on the owner field.
+ * After acquiring lock in the slowpath set ctx and wake up any
+ * waiters so they can recheck.
*
+ * Callers must hold the mutex wait_lock.
*/
+static __always_inline void
+ww_mutex_set_context_slowpath(struct ww_mutex *lock,
+ struct ww_acquire_ctx *ctx)
+{
+ struct mutex_waiter *cur;
-/*
- * Mutex spinning code migrated from kernel/sched/core.c
- */
+ ww_mutex_lock_acquired(lock, ctx);
+ lock->ctx = ctx;
+
+ /*
+ * Give any possible sleeping processes the chance to wake up,
+ * so they can recheck if they have to back off.
+ */
+ list_for_each_entry(cur, &lock->base.wait_list, list) {
+ debug_mutex_wake_waiter(&lock->base, cur);
+ wake_up_process(cur->task);
+ }
+}
+#ifdef CONFIG_MUTEX_SPIN_ON_OWNER
static inline bool owner_running(struct mutex *lock, struct task_struct *owner)
{
if (lock->owner != owner)
@@ -307,6 +320,11 @@ static bool mutex_optimistic_spin(struct mutex *lock,
if (!mutex_can_spin_on_owner(lock))
goto done;
+ /*
+ * In order to avoid a stampede of mutex spinners trying to
+ * acquire the mutex all at once, the spinners need to take a
+ * MCS (queued) lock first before spinning on the owner field.
+ */
if (!osq_lock(&lock->osq))
goto done;
@@ -469,7 +487,7 @@ void __sched ww_mutex_unlock(struct ww_mutex *lock)
EXPORT_SYMBOL(ww_mutex_unlock);
static inline int __sched
-__mutex_lock_check_stamp(struct mutex *lock, struct ww_acquire_ctx *ctx)
+__ww_mutex_lock_check_stamp(struct mutex *lock, struct ww_acquire_ctx *ctx)
{
struct ww_mutex *ww = container_of(lock, struct ww_mutex, base);
struct ww_acquire_ctx *hold_ctx = ACCESS_ONCE(ww->ctx);
@@ -557,7 +575,7 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass,
}
if (use_ww_ctx && ww_ctx->acquired > 0) {
- ret = __mutex_lock_check_stamp(lock, ww_ctx);
+ ret = __ww_mutex_lock_check_stamp(lock, ww_ctx);
if (ret)
goto err;
}
@@ -569,6 +587,8 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass,
schedule_preempt_disabled();
spin_lock_mutex(&lock->wait_lock, flags);
}
+ __set_task_state(task, TASK_RUNNING);
+
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)))
@@ -582,23 +602,7 @@ skip_wait:
if (use_ww_ctx) {
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;
-
- /*
- * Give any possible sleeping processes the chance to wake up,
- * so they can recheck if they have to back off.
- */
- list_for_each_entry(cur, &lock->wait_list, list) {
- debug_mutex_wake_waiter(lock, cur);
- wake_up_process(cur->task);
- }
+ ww_mutex_set_context_slowpath(ww, ww_ctx);
}
spin_unlock_mutex(&lock->wait_lock, flags);
diff --git a/kernel/locking/mcs_spinlock.c b/kernel/locking/osq_lock.c
index 9887a905a762..c112d00341b0 100644
--- a/kernel/locking/mcs_spinlock.c
+++ b/kernel/locking/osq_lock.c
@@ -1,8 +1,6 @@
#include <linux/percpu.h>
#include <linux/sched.h>
-#include "mcs_spinlock.h"
-
-#ifdef CONFIG_SMP
+#include <linux/osq_lock.h>
/*
* An MCS like lock especially tailored for optimistic spinning for sleeping
@@ -111,7 +109,7 @@ bool osq_lock(struct optimistic_spin_queue *lock)
* cmpxchg in an attempt to undo our queueing.
*/
- while (!smp_load_acquire(&node->locked)) {
+ while (!ACCESS_ONCE(node->locked)) {
/*
* If we need to reschedule bail... so we can block.
*/
@@ -203,6 +201,3 @@ void osq_unlock(struct optimistic_spin_queue *lock)
if (next)
ACCESS_ONCE(next->locked) = 1;
}
-
-#endif
-
diff --git a/kernel/locking/rtmutex.c b/kernel/locking/rtmutex.c
index 7c98873a3077..3059bc2f022d 100644
--- a/kernel/locking/rtmutex.c
+++ b/kernel/locking/rtmutex.c
@@ -1130,6 +1130,7 @@ __rt_mutex_slowlock(struct rt_mutex *lock, int state,
set_current_state(state);
}
+ __set_current_state(TASK_RUNNING);
return ret;
}
@@ -1188,10 +1189,9 @@ rt_mutex_slowlock(struct rt_mutex *lock, int state,
ret = task_blocks_on_rt_mutex(lock, &waiter, current, chwalk);
if (likely(!ret))
+ /* sleep on the mutex */
ret = __rt_mutex_slowlock(lock, state, timeout, &waiter);
- set_current_state(TASK_RUNNING);
-
if (unlikely(ret)) {
remove_waiter(lock, &waiter);
rt_mutex_handle_deadlock(ret, chwalk, &waiter);
@@ -1626,10 +1626,9 @@ int rt_mutex_finish_proxy_lock(struct rt_mutex *lock,
set_current_state(TASK_INTERRUPTIBLE);
+ /* sleep on the mutex */
ret = __rt_mutex_slowlock(lock, TASK_INTERRUPTIBLE, to, waiter);
- set_current_state(TASK_RUNNING);
-
if (unlikely(ret))
remove_waiter(lock, waiter);
diff --git a/kernel/locking/rwsem-spinlock.c b/kernel/locking/rwsem-spinlock.c
index 2c93571162cb..2555ae15ec14 100644
--- a/kernel/locking/rwsem-spinlock.c
+++ b/kernel/locking/rwsem-spinlock.c
@@ -154,7 +154,7 @@ void __sched __down_read(struct rw_semaphore *sem)
set_task_state(tsk, TASK_UNINTERRUPTIBLE);
}
- tsk->state = TASK_RUNNING;
+ __set_task_state(tsk, TASK_RUNNING);
out:
;
}
diff --git a/kernel/locking/rwsem-xadd.c b/kernel/locking/rwsem-xadd.c
index 7628c3fc37ca..2f7cc4076f50 100644
--- a/kernel/locking/rwsem-xadd.c
+++ b/kernel/locking/rwsem-xadd.c
@@ -242,8 +242,7 @@ struct rw_semaphore __sched *rwsem_down_read_failed(struct rw_semaphore *sem)
schedule();
}
- tsk->state = TASK_RUNNING;
-
+ __set_task_state(tsk, TASK_RUNNING);
return sem;
}
EXPORT_SYMBOL(rwsem_down_read_failed);