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locking/mutexes: Introduce cancelable MCS lock for adaptive spinning

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Since we want a task waiting for a mutex_lock() to go to sleep and
reschedule on need_resched() we must be able to abort the
mcs_spin_lock() around the adaptive spin.

Therefore implement a cancelable mcs lock.

Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: chegu_vinod@hp.com
Cc: paulmck@linux.vnet.ibm.com
Cc: Waiman.Long@hp.com
Cc: torvalds@linux-foundation.org
Cc: tglx@linutronix.de
Cc: riel@redhat.com
Cc: akpm@linux-foundation.org
Cc: davidlohr@hp.com
Cc: hpa@zytor.com
Cc: andi@firstfloor.org
Cc: aswin@hp.com
Cc: scott.norton@hp.com
Cc: Jason Low <jason.low2@hp.com>
Link: http://lkml.kernel.org/n/tip-62hcl5wxydmjzd182zhvk89m@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Peter Zijlstra
2014-01-29 12:51:42 +01:00
committed by Ingo Molnar
parent 1d8fe7dc80
commit fb0527bd5e
5 changed files with 202 additions and 7 deletions
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10
kernel/locking/mutex.c
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@@ -53,7 +53,7 @@ __mutex_init(struct mutex *lock, const char *name, struct lock_class_key *key)
INIT_LIST_HEAD(&lock->wait_list);
mutex_clear_owner(lock);
#ifdef CONFIG_MUTEX_SPIN_ON_OWNER
lock->mcs_lock = NULL;
lock->osq = NULL;
#endif
debug_mutex_init(lock, name, key);
@@ -403,7 +403,9 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass,
if (!mutex_can_spin_on_owner(lock))
goto slowpath;
mcs_spin_lock(&lock->mcs_lock, &node);
if (!osq_lock(&lock->osq))
goto slowpath;
for (;;) {
struct task_struct *owner;
@@ -442,7 +444,7 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass,
}
mutex_set_owner(lock);
mcs_spin_unlock(&lock->mcs_lock, &node);
osq_unlock(&lock->osq);
preempt_enable();
return 0;
}
@@ -464,7 +466,7 @@ __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass,
*/
arch_mutex_cpu_relax();
}
mcs_spin_unlock(&lock->mcs_lock, &node);
osq_unlock(&lock->osq);
slowpath:
#endif
spin_lock_mutex(&lock->wait_lock, flags);