diff options
| author | Will Deacon <[email protected]> | 2017-10-12 13:20:48 +0100 |
|---|---|---|
| committer | Ingo Molnar <[email protected]> | 2017-10-25 10:57:24 +0200 |
| commit | 4df714be4dcf40bfb0d4af0f851a6e1977afa02e (patch) | |
| tree | 48e4dfcb6fdd4fb4c4701ea52660dd6cbae9f0cf /include/linux | |
| parent | e0d02285f16e8d5810f3d5d5e8a5886ca0015d3b (diff) | |
locking/atomic: Add atomic_cond_read_acquire()
smp_cond_load_acquire() provides a way to spin on a variable with acquire
semantics until some conditional expression involving the variable is
satisfied. Architectures such as arm64 can potentially enter a low-power
state, waking up only when the value of the variable changes, which
reduces the system impact of tight polling loops.
This patch makes the same interface available to users of atomic_t,
atomic64_t and atomic_long_t, rather than require messy accesses to the
structure internals.
Signed-off-by: Will Deacon <[email protected]>
Acked-by: Peter Zijlstra <[email protected]>
Cc: Boqun Feng <[email protected]>
Cc: [email protected]
Cc: Linus Torvalds <[email protected]>
Cc: Paul E. McKenney <[email protected]>
Cc: Thomas Gleixner <[email protected]>
Cc: Waiman Long <[email protected]>
Cc: [email protected]
Link: http://lkml.kernel.org/r/[email protected]
Signed-off-by: Ingo Molnar <[email protected]>
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/atomic.h | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/include/linux/atomic.h b/include/linux/atomic.h index 40d6bfec0e0d..0aeb2b3f4578 100644 --- a/include/linux/atomic.h +++ b/include/linux/atomic.h @@ -653,6 +653,8 @@ static inline int atomic_dec_if_positive(atomic_t *v) } #endif +#define atomic_cond_read_acquire(v, c) smp_cond_load_acquire(&(v)->counter, (c)) + #ifdef CONFIG_GENERIC_ATOMIC64 #include <asm-generic/atomic64.h> #endif @@ -1072,6 +1074,8 @@ static inline long long atomic64_fetch_andnot_release(long long i, atomic64_t *v } #endif +#define atomic64_cond_read_acquire(v, c) smp_cond_load_acquire(&(v)->counter, (c)) + #include <asm-generic/atomic-long.h> #endif /* _LINUX_ATOMIC_H */ |