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locking/atomic: Introduce atomic_fetch_or()

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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>
This commit is contained in:
Frederic Weisbecker 2016-03-24 15:37:59 +01:00 committed by Ingo Molnar
parent 1993b176a8
commit 5acba71e18
1 changed files with 21 additions and 0 deletions
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21
include/linux/atomic.h
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@ -558,6 +558,27 @@ 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