| commit | bffff2e16f50ba5e6cbe4e5ccdb2e478965de06d | [log] [tgz] |
|---|---|---|
| author | Andrea Parri <parri.andrea@gmail.com> | Tue Feb 20 19:45:56 2018 +0100 |
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | Wed May 30 07:50:28 2018 +0200 |
| tree | d22638193c77efb4b1759404faee7c63435f66b9 | |
| parent | be4132e07364c5a758ac9d0c8e89dbf663f41f78 [diff] |
locking/xchg/alpha: Add unconditional memory barrier to cmpxchg() [ Upstream commit cb13b424e986aed68d74cbaec3449ea23c50e167 ] Continuing along with the fight against smp_read_barrier_depends() [1] (or rather, against its improper use), add an unconditional barrier to cmpxchg. This guarantees that dependency ordering is preserved when a dependency is headed by an unsuccessful cmpxchg. As it turns out, the change could enable further simplification of LKMM as proposed in [2]. [1] https://marc.info/?l=linux-kernel&m=150884953419377&w=2 https://marc.info/?l=linux-kernel&m=150884946319353&w=2 https://marc.info/?l=linux-kernel&m=151215810824468&w=2 https://marc.info/?l=linux-kernel&m=151215816324484&w=2 [2] https://marc.info/?l=linux-kernel&m=151881978314872&w=2 Signed-off-by: Andrea Parri <parri.andrea@gmail.com> Acked-by: Peter Zijlstra <peterz@infradead.org> Acked-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: Alan Stern <stern@rowland.harvard.edu> Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Matt Turner <mattst88@gmail.com> Cc: Richard Henderson <rth@twiddle.net> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Will Deacon <will.deacon@arm.com> Cc: linux-alpha@vger.kernel.org Link: http://lkml.kernel.org/r/1519152356-4804-1-git-send-email-parri.andrea@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org> Signed-off-by: Sasha Levin <alexander.levin@microsoft.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>