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From: Peter Zijlstra <peterz@infradead.org>
To: Michael Ellerman <mpe@ellerman.id.au>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
	dja@axtens.net, elver@google.com, linux-kernel@vger.kernel.org,
	linuxppc-dev@lists.ozlabs.org, christophe.leroy@c-s.fr,
	linux-s390@vger.kernel.org, linux-arch@vger.kernel.org,
	x86@kernel.org, kasan-dev@googlegroups.com,
	Will Deacon <will@kernel.org>,
	Mark Rutland <mark.rutland@arm.com>
Subject: Re: [GIT PULL] Please pull powerpc/linux.git powerpc-5.5-2 tag (topic/kasan-bitops)
Date: Fri, 6 Dec 2019 14:16:50 +0100	[thread overview]
Message-ID: <20191206131650.GM2827@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <87blslei5o.fsf@mpe.ellerman.id.au>

On Fri, Dec 06, 2019 at 11:46:11PM +1100, Michael Ellerman wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA256
> 
> Hi Linus,
> 
> Please pull another powerpc update for 5.5.
> 
> As you'll see from the diffstat this is mostly not powerpc code. In order to do
> KASAN instrumentation of bitops we needed to juggle some of the generic bitops
> headers.
> 
> Because those changes potentially affect several architectures I wasn't
> confident putting them directly into my tree, so I've had them sitting in a
> topic branch. That branch (topic/kasan-bitops) has been in linux-next for a
> month, and I've not had any feedback that it's caused any problems.
> 
> So I think this is good to merge, but it's a standalone pull so if anyone does
> object it's not a problem.

No objections, but here:

  https://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux.git/commit/?h=topic/kasan-bitops&id=81d2c6f81996e01fbcd2b5aeefbb519e21c806e9

you write:

  "Currently bitops-instrumented.h assumes that the architecture provides
atomic, non-atomic and locking bitops (e.g. both set_bit and __set_bit).
This is true on x86 and s390, but is not always true: there is a
generic bitops/non-atomic.h header that provides generic non-atomic
operations, and also a generic bitops/lock.h for locking operations."

Is there any actual benefit for PPC to using their own atomic bitops
over bitops/lock.h ? I'm thinking that the generic code is fairly
optimal for most LL/SC architectures.

I've been meaning to audit the various architectures and move them over,
but alas, it's something I've not yet had time for...

  reply	other threads:[~2019-12-06 13:17 UTC|newest]

Thread overview: 43+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-12-06 12:46 Michael Ellerman
2019-12-06 13:16 ` Peter Zijlstra [this message]
2019-12-10  5:38   ` Michael Ellerman
2019-12-10 10:15     ` Peter Zijlstra
2019-12-11  0:29       ` Michael Ellerman
2019-12-12  5:42   ` READ_ONCE() + STACKPROTECTOR_STRONG == :/ (was Re: [GIT PULL] Please pull powerpc/linux.git powerpc-5.5-2 tag (topic/kasan-bitops)) Michael Ellerman
2019-12-12  8:01     ` Peter Zijlstra
2019-12-12 10:07       ` Will Deacon
2019-12-12 10:46         ` Peter Zijlstra
2019-12-12 17:04           ` Will Deacon
2019-12-12 17:16             ` Will Deacon
2019-12-12 17:41           ` Linus Torvalds
2019-12-12 17:50             ` Segher Boessenkool
2019-12-12 18:06             ` Will Deacon
2019-12-12 18:29               ` Christian Borntraeger
2019-12-12 18:43               ` Linus Torvalds
2019-12-12 19:34                 ` Will Deacon
2019-12-12 20:21                   ` Peter Zijlstra
2019-12-12 20:53                     ` Peter Zijlstra
2019-12-13 10:47                       ` Luc Van Oostenryck
2019-12-13 12:56                         ` Peter Zijlstra
2019-12-13 14:28                           ` Luc Van Oostenryck
2019-12-12 20:49                   ` Linus Torvalds
2019-12-13 13:17                     ` Arnd Bergmann
2019-12-13 21:32                       ` Arnd Bergmann
2019-12-13 22:01                         ` Linus Torvalds
2019-12-16 10:28                       ` Will Deacon
2019-12-16 11:47                         ` Peter Zijlstra
2019-12-16 12:06                         ` Arnd Bergmann
2019-12-17 17:07                     ` Will Deacon
2019-12-17 18:04                       ` Linus Torvalds
2019-12-17 18:05                         ` Linus Torvalds
2019-12-17 18:31                           ` Will Deacon
2019-12-17 18:32                         ` Linus Torvalds
2019-12-18 12:17                           ` Michael Ellerman
2019-12-19 12:11                           ` Will Deacon
2019-12-18 10:22                     ` Christian Borntraeger
2019-12-18 10:35                       ` Will Deacon
2019-12-13 12:07           ` Michael Ellerman
2019-12-13 13:53             ` Segher Boessenkool
2019-12-13 21:06               ` Michael Ellerman
2019-12-12 15:10     ` Segher Boessenkool
2019-12-06 22:15 ` [GIT PULL] Please pull powerpc/linux.git powerpc-5.5-2 tag (topic/kasan-bitops) pr-tracker-bot

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