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From: Thomas Gleixner <tglx@linutronix.de>
To: Dmitry Vyukov <dvyukov@google.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>,
	Mark Rutland <mark.rutland@arm.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Will Deacon <will.deacon@arm.com>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Andrey Ryabinin <aryabinin@virtuozzo.com>,
	kasan-dev <kasan-dev@googlegroups.com>,
	"x86@kernel.org" <x86@kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>,
	Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH] locking/atomics: don't alias ____ptr
Date: Wed, 28 Jun 2017 14:24:50 +0200 (CEST)	[thread overview]
Message-ID: <alpine.DEB.2.20.1706281423390.1970@nanos> (raw)
In-Reply-To: <CACT4Y+YqCP8RC9nRo5oBw2GFdFF+AVJgpcGGENR7hHL9s3GSHg@mail.gmail.com>

On Wed, 28 Jun 2017, Dmitry Vyukov wrote:
> On Wed, Jun 28, 2017 at 1:10 PM, Thomas Gleixner <tglx@linutronix.de> wrote:
> >  #define cmpxchg_local(ptr, old, new)                   \
> >  ({                                                     \
> > -       __typeof__(ptr) ____ptr = (ptr);                \
> > -       kasan_check_write(____ptr, sizeof(*____ptr));   \
> > -       arch_cmpxchg_local(____ptr, (old), (new));      \
> > +       kasan_check_write((ptr), sizeof(*(ptr)));       \
> > +       arch_cmpxchg_local((ptr), (old), (new));        \
> 
> 
> /\/\/\/\/\/\/\/\/\/\/\/\
> 
> These are macros.
> If ptr is foo(), then we will call foo() twice.

If that's true, the foo() will be evaluated a gazillion more times down the
way to the end of this macro maze.

Thanks,

	tglx

WARNING: multiple messages have this Message-ID (diff)
From: Thomas Gleixner <tglx@linutronix.de>
To: Dmitry Vyukov <dvyukov@google.com>
Cc: Sebastian Andrzej Siewior <bigeasy@linutronix.de>,
	Ingo Molnar <mingo@redhat.com>,
	Mark Rutland <mark.rutland@arm.com>,
	Peter Zijlstra <peterz@infradead.org>,
	Will Deacon <will.deacon@arm.com>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Andrey Ryabinin <aryabinin@virtuozzo.com>,
	kasan-dev <kasan-dev@googlegroups.com>,
	"x86@kernel.org" <x86@kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>,
	Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH] locking/atomics: don't alias ____ptr
Date: Wed, 28 Jun 2017 14:24:50 +0200 (CEST)	[thread overview]
Message-ID: <alpine.DEB.2.20.1706281423390.1970@nanos> (raw)
In-Reply-To: <CACT4Y+YqCP8RC9nRo5oBw2GFdFF+AVJgpcGGENR7hHL9s3GSHg@mail.gmail.com>

On Wed, 28 Jun 2017, Dmitry Vyukov wrote:
> On Wed, Jun 28, 2017 at 1:10 PM, Thomas Gleixner <tglx@linutronix.de> wrote:
> >  #define cmpxchg_local(ptr, old, new)                   \
> >  ({                                                     \
> > -       __typeof__(ptr) ____ptr = (ptr);                \
> > -       kasan_check_write(____ptr, sizeof(*____ptr));   \
> > -       arch_cmpxchg_local(____ptr, (old), (new));      \
> > +       kasan_check_write((ptr), sizeof(*(ptr)));       \
> > +       arch_cmpxchg_local((ptr), (old), (new));        \
> 
> 
> /\/\/\/\/\/\/\/\/\/\/\/\
> 
> These are macros.
> If ptr is foo(), then we will call foo() twice.

If that's true, the foo() will be evaluated a gazillion more times down the
way to the end of this macro maze.

Thanks,

	tglx

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  parent reply	other threads:[~2017-06-28 12:25 UTC|newest]

Thread overview: 62+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-06-22 14:14 [PATCH v5 0/4] x86, kasan: add KASAN checks to atomic operations Dmitry Vyukov
     [not found] ` <cover.1498140838.git.dvyukov@google.com>
2017-06-22 14:14   ` [PATCH v5 1/4] x86: switch atomic.h to use atomic-instrumented.h Dmitry Vyukov
2017-06-22 14:14     ` Dmitry Vyukov
2017-06-22 21:14     ` Andrew Morton
2017-06-22 21:14       ` Andrew Morton
2017-06-23  8:23       ` Dmitry Vyukov
2017-06-23  8:23         ` Dmitry Vyukov
2017-06-23  8:54         ` Ingo Molnar
2017-06-23  8:54           ` Ingo Molnar
2017-06-23 19:00           ` Andrew Morton
2017-06-23 19:00             ` Andrew Morton
2017-06-23 13:59     ` [tip:locking/core] locking/atomic/x86: Switch " tip-bot for Dmitry Vyukov
2017-06-22 14:14   ` [PATCH v5 2/4] kasan: allow kasan_check_read/write() to accept pointers to volatiles Dmitry Vyukov
2017-06-22 14:14     ` Dmitry Vyukov
2017-06-23 14:00     ` [tip:locking/core] kasan: Allow " tip-bot for Dmitry Vyukov
2017-07-26 12:10     ` tip-bot for Dmitry Vyukov
2017-06-22 14:14   ` [PATCH v5 3/4] asm-generic: add KASAN instrumentation to atomic operations Dmitry Vyukov
2017-06-22 14:14     ` Dmitry Vyukov
2017-06-23 14:01     ` [tip:locking/core] locking/atomics, asm-generic: Add " tip-bot for Dmitry Vyukov
2017-06-28 10:02     ` [PATCH] locking/atomics: don't alias ____ptr Sebastian Andrzej Siewior
2017-06-28 10:02       ` Sebastian Andrzej Siewior
2017-06-28 10:16       ` Dmitry Vyukov
2017-06-28 10:16         ` Dmitry Vyukov
2017-06-28 11:10         ` Thomas Gleixner
2017-06-28 11:10           ` Thomas Gleixner
2017-06-28 11:12           ` Dmitry Vyukov
2017-06-28 11:12             ` Dmitry Vyukov
2017-06-28 11:21             ` Thomas Gleixner
2017-06-28 11:21               ` Thomas Gleixner
2017-06-28 12:45               ` Mark Rutland
2017-06-28 12:45                 ` Mark Rutland
2017-06-28 12:24             ` Thomas Gleixner [this message]
2017-06-28 12:24               ` Thomas Gleixner
2017-06-28 12:27               ` Dmitry Vyukov
2017-06-28 12:27                 ` Dmitry Vyukov
2017-06-28 13:33                 ` Thomas Gleixner
2017-06-28 13:33                   ` Thomas Gleixner
2017-06-28 11:15         ` Andrey Ryabinin
2017-06-28 11:15           ` Andrey Ryabinin
2017-06-28 12:12           ` Sebastian Andrzej Siewior
2017-06-28 12:12             ` Sebastian Andrzej Siewior
2017-06-28 13:20             ` Thomas Gleixner
2017-06-28 13:20               ` Thomas Gleixner
2017-06-28 13:54               ` Thomas Gleixner
2017-06-28 13:54                 ` Thomas Gleixner
2017-06-28 14:14                 ` Mark Rutland
2017-06-28 14:14                   ` Mark Rutland
2017-06-28 15:24                   ` Thomas Gleixner
2017-06-28 15:24                     ` Thomas Gleixner
2017-06-28 15:54                     ` Mark Rutland
2017-06-28 15:54                       ` Mark Rutland
2017-06-28 16:56                       ` Ingo Molnar
2017-06-28 16:56                         ` Ingo Molnar
2017-06-28 18:21                       ` Thomas Gleixner
2017-06-28 18:21                         ` Thomas Gleixner
2017-06-29  6:47                         ` Thomas Gleixner
2017-06-29  6:47                           ` Thomas Gleixner
2017-06-28 14:00               ` Andrey Ryabinin
2017-06-28 14:00                 ` Andrey Ryabinin
2017-06-22 14:14   ` [PATCH v5 4/4] asm-generic, x86: add comments for atomic instrumentation Dmitry Vyukov
2017-06-22 14:14     ` Dmitry Vyukov
2017-06-23 14:01     ` [tip:locking/core] locking/atomic/x86, asm-generic: Add " tip-bot for Dmitry Vyukov

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