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authorDavidlohr Bueso <dave@stgolabs.net>2015-06-30 14:58:39 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2015-06-30 19:44:58 -0700
commitff35e5ef86fea1fa84eb7fdc939d0b1e3f1222bf (patch)
treedcbd89deb61c178925663ce5ad0457f232715a23 /ipc/util.h
parentc5c8975b2eb4eb7604e8ce4f762987f56d2a96a2 (diff)
ipc,msg: provide barrier pairings for lockless receive
We currently use a full barrier on the sender side to to avoid receiver tasks disappearing on us while still performing on the sender side wakeup. We lack however, the proper CPU-CPU interactions pairing on the receiver side which busy-waits for the message. Similarly, we do not need a full smp_mb, and can relax the semantics for the writer and reader sides of the message. This is safe as we are only ordering loads and stores to r_msg. And in both smp_wmb and smp_rmb, there are no stores after the calls _anyway_. This obviously applies for pipelined_send and expunge_all, for EIRDM when destroying a queue. Signed-off-by: Davidlohr Bueso <dbueso@suse.de> Cc: Manfred Spraul <manfred@colorfullife.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'ipc/util.h')
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