| Date | Tue, 31 May 2016 12:19:57 +0200 | From | Peter Zijlstra <> | Subject | [PATCH -v2 32/33] locking,qrwlock: Employ atomic_fetch_add_acquire() |
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The only reason for the current code is to make GCC emit only the "LOCK XADD" instruction on x86 (and not do a pointless extra ADD on the result), do so nicer.
Acked-by: Waiman Long <waiman.long@hpe.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> --- kernel/locking/qrwlock.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)
--- a/kernel/locking/qrwlock.c +++ b/kernel/locking/qrwlock.c @@ -93,7 +93,7 @@ void queued_read_lock_slowpath(struct qr * that accesses can't leak upwards out of our subsequent critical * section in the case that the lock is currently held for write. */ - cnts = atomic_add_return_acquire(_QR_BIAS, &lock->cnts) - _QR_BIAS; + cnts = atomic_fetch_add_acquire(_QR_BIAS, &lock->cnts); rspin_until_writer_unlock(lock, cnts); /*
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