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asm/rwonce: Allow __READ_ONCE to be overridden by the architecture

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The meat and potatoes of READ_ONCE() is defined by the __READ_ONCE()
macro, which uses a volatile casts in an attempt to avoid tearing of
byte, halfword, word and double-word accesses. Allow this to be
overridden by the architecture code in the case that things like memory
barriers are also required.

Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Will Deacon <will@kernel.org>
This commit is contained in:
Will Deacon 2019-10-15 17:30:47 -07:00
parent e506ea4512
commit b78b331a3f
1 changed files with 2 additions and 0 deletions
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2
include/asm-generic/rwonce.h
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@ -43,7 +43,9 @@
* atomicity or dependency ordering guarantees. Note that this may result
* in tears!
*/
#ifndef __READ_ONCE
#define __READ_ONCE(x) (*(const volatile __unqual_scalar_typeof(x) *)&(x))
#endif
#define __READ_ONCE_SCALAR(x) \
({ \