diff options
| author |   Will Deacon <will.deacon@arm.com> | 2017-10-12 13:20:48 +0100 |
|---|---|---|
| committer |   Ingo Molnar <mingo@kernel.org> | 2017-10-25 10:57:24 +0200 |
| commit | 4df714be4dcf40bfb0d4af0f851a6e1977afa02e (patch) | |
| tree | 48e4dfcb6fdd4fb4c4701ea52660dd6cbae9f0cf /include/asm-generic | |
| parent | locking/qrwlock: Use 'struct qrwlock' instead of 'struct __qrwlock' (diff) | |
| download | linux-dev-4df714be4dcf40bfb0d4af0f851a6e1977afa02e.tar.xz linux-dev-4df714be4dcf40bfb0d4af0f851a6e1977afa02e.zip | |
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 <will.deacon@arm.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Cc: Boqun Feng <boqun.feng@gmail.com>
Cc: Jeremy.Linton@arm.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Waiman Long <longman@redhat.com>
Cc: linux-arm-kernel@lists.infradead.org
Link: http://lkml.kernel.org/r/1507810851-306-3-git-send-email-will.deacon@arm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'include/asm-generic')
| -rw-r--r-- | include/asm-generic/atomic-long.h | 3 |
1 files changed, 3 insertions, 0 deletions
diff --git a/include/asm-generic/atomic-long.h b/include/asm-generic/atomic-long.h index 288cc9e96395..f2d97b782031 100644 --- a/include/asm-generic/atomic-long.h +++ b/include/asm-generic/atomic-long.h @@ -243,4 +243,7 @@ static inline long atomic_long_add_unless(atomic_long_t *l, long a, long u) #define atomic_long_inc_not_zero(l) \ ATOMIC_LONG_PFX(_inc_not_zero)((ATOMIC_LONG_PFX(_t) *)(l)) +#define atomic_long_cond_read_acquire(v, c) \ + ATOMIC_LONG_PFX(_cond_read_acquire)((ATOMIC_LONG_PFX(_t) *)(v), (c)) + #endif /* _ASM_GENERIC_ATOMIC_LONG_H */ |