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authorPeter Zijlstra <peterz@infradead.org>2015-09-18 14:22:52 +0300
committerIngo Molnar <mingo@kernel.org>2015-09-23 10:54:29 +0300
commite3e72ab80a3fac0b88e07d358a2c75724ccd66b4 (patch)
tree3cc1b2f6fbe8ca8d3649d95d14f7c093cea11480 /include/asm-generic/atomic-long.h
parent62e8a3258bda118f24ff462fe04cfbe75b8189b5 (diff)
downloadlinux-e3e72ab80a3fac0b88e07d358a2c75724ccd66b4.tar.xz
atomic: Implement atomic_read_ctrl()
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>
Diffstat (limited to 'include/asm-generic/atomic-long.h')
-rw-r--r--include/asm-generic/atomic-long.h3
1 files changed, 2 insertions, 1 deletions
diff --git a/include/asm-generic/atomic-long.h b/include/asm-generic/atomic-long.h
index c7a5c1ad2ed3..8942cdc676a7 100644
--- a/include/asm-generic/atomic-long.h
+++ b/include/asm-generic/atomic-long.h
@@ -35,7 +35,7 @@ typedef atomic_t atomic_long_t;
#endif
#define ATOMIC_LONG_READ_OP(mo) \
-static inline long atomic_long_read##mo(atomic_long_t *l) \
+static inline long atomic_long_read##mo(const atomic_long_t *l) \
{ \
ATOMIC_LONG_PFX(_t) *v = (ATOMIC_LONG_PFX(_t) *)l; \
\
@@ -43,6 +43,7 @@ static inline long atomic_long_read##mo(atomic_long_t *l) \
}
ATOMIC_LONG_READ_OP()
ATOMIC_LONG_READ_OP(_acquire)
+ATOMIC_LONG_READ_OP(_ctrl)
#undef ATOMIC_LONG_READ_OP