malhuda/msm-4.14
1
0
Fork 0
mirror of https://github.com/rd-stuffs/msm-4.14.git synced 2025-02-20 11:45:48 +08:00
Code Issues Actions Packages Projects Releases Wiki Activity

BACKPORT: atomic: Add irqsave variant of atomic_dec_and_lock()

Browse Source 
There are in-tree users of atomic_dec_and_lock() which must acquire the
spin lock with interrupts disabled. To workaround the lack of an irqsave
variant of atomic_dec_and_lock() they use local_irq_save() at the call
site. This causes extra code and creates in some places unneeded long
interrupt disabled times. These places need also extra treatment for
PREEMPT_RT due to the disconnect of the irq disabling and the lock
function.

Implement the missing irqsave variant of the function.

Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r20180612161621.22645-3-bigeasy@linutronix.de

(cherry picked from commit ccfbb5bed407053b27492a9adc06064d949a9aa6)
BUG: 137270441
Change-Id: I49051801a73ac0de11d71bfa23930ce4826f7c61
Signed-off-by: Satya Tangirala <satyat@google.com>
This commit is contained in:
Anna-Maria Gleixner 2018-06-12 18:16:20 +02:00 committed by Satya Tangirala
parent 334164ca0f
commit 9771d9b377
2 changed files with 21 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

5
include/linux/spinlock.h
View File

@ -421,4 +421,9 @@ extern int _atomic_dec_and_lock(atomic_t *atomic, spinlock_t *lock);
#define atomic_dec_and_lock(atomic, lock) \
__cond_lock(lock, _atomic_dec_and_lock(atomic, lock))
extern int _atomic_dec_and_lock_irqsave(atomic_t *atomic, spinlock_t *lock,
unsigned long *flags);
#define atomic_dec_and_lock_irqsave(atomic, lock, flags) \
__cond_lock(lock, _atomic_dec_and_lock_irqsave(atomic, lock, &(flags)))
#endif /* __LINUX_SPINLOCK_H */

16
lib/dec_and_lock.c
View File

@ -33,3 +33,19 @@ int _atomic_dec_and_lock(atomic_t *atomic, spinlock_t *lock)
}
EXPORT_SYMBOL(_atomic_dec_and_lock);
int _atomic_dec_and_lock_irqsave(atomic_t *atomic, spinlock_t *lock,
unsigned long *flags)
{
/* Subtract 1 from counter unless that drops it to 0 (ie. it was 1) */
if (atomic_add_unless(atomic, -1, 1))
return 0;
/* Otherwise do it the slow way */
spin_lock_irqsave(lock, *flags);
if (atomic_dec_and_test(atomic))
return 1;
spin_unlock_irqrestore(lock, *flags);
return 0;
}
EXPORT_SYMBOL(_atomic_dec_and_lock_irqsave);