From: Will Deacon <will.deacon@arm.com>
To: Boqun Feng <boqun.feng@gmail.com>
Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@kernel.org>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
Michael Ellerman <mpe@ellerman.id.au>,
Thomas Gleixner <tglx@linutronix.de>,
"Paul E. McKenney" <paulmck@linux.vnet.ibm.com>,
Waiman Long <waiman.long@hp.com>,
Davidlohr Bueso <dave@stgolabs.net>
Subject: Re: [PATCH v3 6/6] powerpc: atomic: Implement cmpxchg{,64}_* and atomic{,64}_cmpxchg_* variants
Date: Tue, 13 Oct 2015 16:04:27 +0100 [thread overview]
Message-ID: <20151013150427.GP21550@arm.com> (raw)
In-Reply-To: <20151013145830.GC23991@fixme-laptop.cn.ibm.com>
On Tue, Oct 13, 2015 at 10:58:30PM +0800, Boqun Feng wrote:
> On Tue, Oct 13, 2015 at 03:43:33PM +0100, Will Deacon wrote:
> > Putting a barrier in the middle of that critical section is probably a
> > terrible idea, and that's why I thought you were avoiding it (hence my
>
> The fact is that I haven't thought of that way to implement
> cmpxchg_release before you ask that question ;-) And I'm not going to do
> that for now and probably not in the future.
>
> > original question). Perhaps just add a comment to that effect, since I
>
> Are you suggesting if I put a barrier in the middle I'd better to add a
> comment, right? So if I don't do that, it's OK to let this patch as it.
No, I mean put a comment in your file to explain the reason why you
override _relaxed and _acquire, but not _release (because overriding
_release would introduce this weird barrier in the middle of the critical
section, which would likely cause the conditional store to fail).
Will
next prev parent reply other threads:[~2015-10-13 15:04 UTC|newest]
Thread overview: 40+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-10-12 14:14 [PATCH v3 0/6] atomics: powerpc: Implement relaxed/acquire/release variants of some atomics Boqun Feng
2015-10-12 14:14 ` [PATCH v3 1/6] powerpc: atomic: Make *xchg and *cmpxchg a full barrier Boqun Feng
2015-10-12 14:23 ` Boqun Feng
2015-10-12 14:14 ` [PATCH v3 2/6] atomics: Add test for atomic operations with _relaxed variants Boqun Feng
[not found] ` <201510122205.Uu3yljqf%fengguang.wu@intel.com>
[not found] ` <20151012145652.GJ27351@fixme-laptop.cn.ibm.com>
2015-10-12 15:29 ` [lkp] " Fengguang Wu
2015-10-12 15:42 ` Boqun Feng
2015-10-12 16:02 ` [kbuild-all] " Fengguang Wu
2015-10-12 16:09 ` Fengguang Wu
2015-10-13 1:33 ` Boqun Feng
2015-10-12 14:14 ` [PATCH v3 3/6] atomics: Allow architectures to define their own __atomic_op_* helpers Boqun Feng
2015-10-12 14:14 ` [PATCH v3 4/6] powerpc: atomic: Implement atomic{, 64}_*_return_* variants Boqun Feng
2015-10-12 14:14 ` [PATCH v3 4/6] powerpc: atomic: Implement atomic{,64}_*_return_* variants Boqun Feng
2015-10-13 13:21 ` [PATCH v3 4/6] powerpc: atomic: Implement atomic{, 64}_*_return_* variants Will Deacon
2015-10-13 13:21 ` [PATCH v3 4/6] powerpc: atomic: Implement atomic{,64}_*_return_* variants Will Deacon
2015-10-13 13:35 ` [PATCH v3 4/6] powerpc: atomic: Implement atomic{, 64}_*_return_* variants Boqun Feng
2015-10-13 13:35 ` [PATCH v3 4/6] powerpc: atomic: Implement atomic{,64}_*_return_* variants Boqun Feng
2015-10-14 1:00 ` [PATCH v3 4/6] powerpc: atomic: Implement atomic{, 64}_*_return_* variants Boqun Feng
2015-10-14 1:00 ` [PATCH v3 4/6] powerpc: atomic: Implement atomic{,64}_*_return_* variants Boqun Feng
2015-10-12 14:14 ` [PATCH v3 5/6] powerpc: atomic: Implement xchg_* and atomic{, 64}_xchg_* variants Boqun Feng
2015-10-12 14:14 ` [PATCH v3 5/6] powerpc: atomic: Implement xchg_* and atomic{,64}_xchg_* variants Boqun Feng
2015-10-12 14:14 ` [PATCH v3 6/6] powerpc: atomic: Implement cmpxchg{, 64}_* and atomic{, 64}_cmpxchg_* variants Boqun Feng
2015-10-12 14:14 ` [PATCH v3 6/6] powerpc: atomic: Implement cmpxchg{,64}_* and atomic{,64}_cmpxchg_* variants Boqun Feng
2015-10-13 13:24 ` Will Deacon
2015-10-13 14:32 ` Boqun Feng
2015-10-13 14:43 ` Will Deacon
2015-10-13 14:58 ` Boqun Feng
2015-10-13 15:04 ` Will Deacon [this message]
2015-10-13 15:45 ` Boqun Feng
2015-10-14 1:47 ` Boqun Feng
2015-10-14 9:40 ` Will Deacon
2015-10-13 14:46 ` Boqun Feng
2015-10-12 14:30 ` [PATCH RESEND v3 1/6] powerpc: atomic: Make *xchg and *cmpxchg a full barrier Boqun Feng
2015-10-14 0:10 ` Michael Ellerman
2015-10-14 0:51 ` Boqun Feng
2015-10-14 8:06 ` Peter Zijlstra
2015-10-14 9:26 ` Boqun Feng
2015-10-14 9:33 ` Peter Zijlstra
2015-10-14 9:43 ` Michael Ellerman
2015-10-13 12:27 ` [PATCH v3 0/6] atomics: powerpc: Implement relaxed/acquire/release variants of some atomics Peter Zijlstra
2015-10-13 15:46 ` Paul E. McKenney
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20151013150427.GP21550@arm.com \
--to=will.deacon@arm.com \
--cc=benh@kernel.crashing.org \
--cc=boqun.feng@gmail.com \
--cc=dave@stgolabs.net \
--cc=linux-kernel@vger.kernel.org \
--cc=linuxppc-dev@lists.ozlabs.org \
--cc=mingo@kernel.org \
--cc=mpe@ellerman.id.au \
--cc=paulmck@linux.vnet.ibm.com \
--cc=paulus@samba.org \
--cc=peterz@infradead.org \
--cc=tglx@linutronix.de \
--cc=waiman.long@hp.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.