Re: [PATCH 6/6] Documentation/memory-barriers.txt: Clarify cmpxchg()

2019-10-15 Thread Waiman Long
On 10/14/19 1:49 PM, Manfred Spraul wrote: > Hello Peter, > > On 10/14/19 3:03 PM, Peter Zijlstra wrote: >> On Sat, Oct 12, 2019 at 07:49:58AM +0200, Manfred Spraul wrote: >>> The documentation in memory-barriers.txt claims that >>> smp_mb__{before,after}_atomic() are for atomic ops that do not ret

Re: [PATCH 6/6] Documentation/memory-barriers.txt: Clarify cmpxchg()

2019-10-15 Thread Davidlohr Bueso
On Tue, 15 Oct 2019, Peter Zijlstra wrote: On Mon, Oct 14, 2019 at 06:26:04PM -0700, Davidlohr Bueso wrote: On Sat, 12 Oct 2019, Manfred Spraul wrote: > Invalid would be: >smp_mb__before_atomic(); >atomic_set(); fyi I've caught a couple of naughty users: drivers/crypto/cavium/nitrox

Re: [PATCH 6/6] Documentation/memory-barriers.txt: Clarify cmpxchg()

2019-10-15 Thread Peter Zijlstra
On Mon, Oct 14, 2019 at 07:49:56PM +0200, Manfred Spraul wrote: > From 61c85a56994e32ea393af9debef4cccd9cd24abd Mon Sep 17 00:00:00 2001 > From: Manfred Spraul > Date: Fri, 11 Oct 2019 10:33:26 +0200 > Subject: [PATCH] Update Documentation for _{acquire|release|relaxed}() > > When adding the _{a

Re: [PATCH 6/6] Documentation/memory-barriers.txt: Clarify cmpxchg()

2019-10-15 Thread Peter Zijlstra
On Mon, Oct 14, 2019 at 06:26:04PM -0700, Davidlohr Bueso wrote: > On Sat, 12 Oct 2019, Manfred Spraul wrote: > > Invalid would be: > > smp_mb__before_atomic(); > > atomic_set(); > > fyi I've caught a couple of naughty users: > > drivers/crypto/cavium/nitrox/nitrox_main.c > drivers/gp

Re: [PATCH 6/6] Documentation/memory-barriers.txt: Clarify cmpxchg()

2019-10-14 Thread Davidlohr Bueso
On Sat, 12 Oct 2019, Manfred Spraul wrote: Invalid would be: smp_mb__before_atomic(); atomic_set(); fyi I've caught a couple of naughty users: drivers/crypto/cavium/nitrox/nitrox_main.c drivers/gpu/drm/msm/adreno/a5xx_preempt.c Thanks, Davidlohr

Re: [PATCH 6/6] Documentation/memory-barriers.txt: Clarify cmpxchg()

2019-10-14 Thread Davidlohr Bueso
On Mon, 14 Oct 2019, Manfred Spraul wrote: I've updated the Change description accordingly I continue to think my memory-barriers.txt change regarding failed Rmw is still good to have. Unless any strong objections, could you also add the patch to the series? Thanks, Davidlohr

Re: [PATCH 6/6] Documentation/memory-barriers.txt: Clarify cmpxchg()

2019-10-14 Thread Manfred Spraul
Hello Peter, On 10/14/19 3:03 PM, Peter Zijlstra wrote: On Sat, Oct 12, 2019 at 07:49:58AM +0200, Manfred Spraul wrote: The documentation in memory-barriers.txt claims that smp_mb__{before,after}_atomic() are for atomic ops that do not return a value. This is misleading and doesn't match the e

Re: [PATCH 6/6] Documentation/memory-barriers.txt: Clarify cmpxchg()

2019-10-14 Thread Peter Zijlstra
On Sat, Oct 12, 2019 at 07:49:58AM +0200, Manfred Spraul wrote: > The documentation in memory-barriers.txt claims that > smp_mb__{before,after}_atomic() are for atomic ops that do not return a > value. > > This is misleading and doesn't match the example in atomic_t.txt, > and e.g. smp_mb__before_

[PATCH 6/6] Documentation/memory-barriers.txt: Clarify cmpxchg()

2019-10-11 Thread Manfred Spraul
The documentation in memory-barriers.txt claims that smp_mb__{before,after}_atomic() are for atomic ops that do not return a value. This is misleading and doesn't match the example in atomic_t.txt, and e.g. smp_mb__before_atomic() may and is used together with cmpxchg_relaxed() in the wake_q code.