diff options
| author | Frederic Weisbecker <fweisbec@gmail.com> | 2016-03-24 15:37:59 +0100 |
|---|---|---|
| committer | Ingo Molnar <mingo@kernel.org> | 2016-03-29 11:52:11 +0200 |
| commit | 5acba71e18833b9d06686b3751598bfa263a3ac3 (patch) | |
| tree | 31ad607ebf024af39acb6ff1a68947fb6c727f03 /include/linux/atomic.h | |
| parent | 1993b176a8224e371e0732ffada7ab9eb3b0912b (diff) | |
locking/atomic: Introduce atomic_fetch_or()
This is deemed to replace the type generic fetch_or() which brings a lot
of issues such as macro induced block variable aliasing and sloppy types.
Not to mention fetch_or() doesn't refer to any namespace, adding even
more confusion.
So lets provide an atomic_t version. Current and next users of fetch_or()
are thus encouraged to use atomic_t.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1458830281-4255-2-git-send-email-fweisbec@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'include/linux/atomic.h')
| -rw-r--r-- | include/linux/atomic.h | 21 |
1 files changed, 21 insertions, 0 deletions
diff --git a/include/linux/atomic.h b/include/linux/atomic.h index df4f369254c0..3d64c0852164 100644 --- a/include/linux/atomic.h +++ b/include/linux/atomic.h @@ -559,6 +559,27 @@ static inline int atomic_dec_if_positive(atomic_t *v) #endif /** + * atomic_fetch_or - perform *p |= mask and return old value of *p + * @p: pointer to atomic_t + * @mask: mask to OR on the atomic_t + */ +#ifndef atomic_fetch_or +static inline int atomic_fetch_or(atomic_t *p, int mask) +{ + int old, val = atomic_read(p); + + for (;;) { + old = atomic_cmpxchg(p, val, val | mask); + if (old == val) + break; + val = old; + } + + return old; +} +#endif + +/** * fetch_or - perform *ptr |= mask and return old value of *ptr * @ptr: pointer to value * @mask: mask to OR on the value |