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Will Deacon authored
The 64-bit cmpxchg operation on the lockref is ordered by virtue of hazarding between the cmpxchg operation and the reference count manipulation. On weakly ordered memory architectures (such as ARM), it can be of great benefit to omit the barrier instructions where they are not needed. This patch moves the lockless lockref code over to a cmpxchg64_relaxed operation, which doesn't provide barrier semantics. If the operation isn't defined, we simply #define it as the usual 64-bit cmpxchg macro. Cc: Waiman Long <Waiman.Long@hp.com> Signed-off-by:
Will Deacon <will.deacon@arm.com> Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org>
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