GitHub-Mirror/linux-bl808
2
0
Fork 0
mirror of https://github.com/Fishwaldo/linux-bl808.git synced 2025-06-17 20:25:19 +00:00
Code Issues Projects Releases Packages Wiki Activity Actions

atomic: Implement atomic_read_ctrl()

Browse source 
Provide atomic_read_ctrl() to mirror READ_ONCE_CTRL(), such that we can
more conveniently use atomics in control dependencies.

Since we can assume atomic_read() implies a READ_ONCE(), we must only
emit an extra smp_read_barrier_depends() in order to upgrade to
READ_ONCE_CTRL() semantics.

Requested-by: Dmitry Vyukov <dvyukov@google.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Will Deacon <will.deacon@arm.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: linux-kernel@vger.kernel.org
Cc: oleg@redhat.com
Link: http://lkml.kernel.org/r/20150918115637.GM3604@twins.programming.kicks-ass.net
Signed-off-by: Ingo Molnar <mingo@kernel.org>
This commit is contained in:
Peter Zijlstra 2015-09-18 13:22:52 +02:00 • committed by Ingo Molnar
parent 62e8a3258b
commit e3e72ab80a
3 changed files with 29 additions and 9 deletions
Download patch file Download diff file Expand all files Collapse all files

18
include/linux/atomic.h
View file

@ -4,6 +4,15 @@
#include <asm/atomic.h>
#include <asm/barrier.h>
#ifndef atomic_read_ctrl
static inline int atomic_read_ctrl(const atomic_t *v)
{
int val = atomic_read(v);
smp_read_barrier_depends(); /* Enforce control dependency. */
return val;
}
#endif
/*
* Relaxed variants of xchg, cmpxchg and some atomic operations.
*
@ -455,6 +464,15 @@ static inline int atomic_dec_if_positive(atomic_t *v)
#include <asm-generic/atomic64.h>
#endif
#ifndef atomic64_read_ctrl
static inline long long atomic64_read_ctrl(const atomic64_t *v)
{
long long val = atomic64_read(v);
smp_read_barrier_depends(); /* Enforce control dependency. */
return val;
}
#endif
#ifndef atomic64_andnot
static inline void atomic64_andnot(long long i, atomic64_t *v)
{