From: Peter Zijlstra <peterz@infradead.org>
To: Will Deacon <will.deacon@arm.com>
Cc: Stafford Horne <shorne@gmail.com>,
Paul McKenney <paulmck@linux.vnet.ibm.com>,
Jonas Bonn <jonas@southpole.se>,
Stefan Kristiansson <stefan.kristiansson@saunalahti.fi>,
David Howells <dhowells@redhat.com>,
Arnd Bergmann <arnd@arndb.de>,
linux-kernel@vger.kernel.org,
Thomas Gleixner <tglx@linutronix.de>
Subject: Re: asm-generic: Disallow no-op mb() for SMP systems
Date: Thu, 1 Feb 2018 16:50:07 +0100 [thread overview]
Message-ID: <20180201155007.GB2249@hirez.programming.kicks-ass.net> (raw)
In-Reply-To: <20180201153951.GG9182@arm.com>
On Thu, Feb 01, 2018 at 03:39:51PM +0000, Will Deacon wrote:
> > I could've gotten my brain in a twist or course, which isn't _that_
> > unusual. I never seem to be able to quite remember the holes you have
> > with ll/sc on arm64 :-)
>
> Is smp_mb__before_atomic supposed to provide ordering guarantees if it's
> used before a failed cmpxchg? If so, I think it's needed here because the
> l.swa might not even execute. Or did I just invent another problem?
I think it should do so indeed (and afaik all our current archs are good
that way).
next prev parent reply other threads:[~2018-02-01 15:50 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-31 13:00 Peter Zijlstra
2018-01-31 13:17 ` Will Deacon
2018-01-31 13:26 ` Peter Zijlstra
2018-02-01 12:27 ` Stafford Horne
2018-02-01 13:29 ` Peter Zijlstra
2018-02-01 13:32 ` Will Deacon
2018-02-01 13:53 ` Peter Zijlstra
2018-02-01 15:39 ` Will Deacon
2018-02-01 15:50 ` Peter Zijlstra [this message]
2018-02-01 15:52 ` Peter Zijlstra
2018-02-02 13:48 ` Stafford Horne
2018-02-02 19:14 ` kbuild test robot
2018-02-03 11:43 ` Peter Zijlstra
2018-02-02 20:00 ` kbuild test robot
2018-02-02 20:25 ` Peter Zijlstra
2018-02-02 21:08 ` Alan Cox
2018-02-03 11:42 ` Peter Zijlstra
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