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From: Peter Zijlstra <peterz@infradead.org>
To: Andy Lutomirski <luto@kernel.org>
Cc: Dmitry Vyukov <dvyukov@google.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Borislav Petkov <bp@alien8.de>, Brian Gerst <brgerst@gmail.com>,
	Denys Vlasenko <dvlasenk@redhat.com>,
	"H. Peter Anvin" <hpa@zytor.com>,
	Josh Poimboeuf <jpoimboe@redhat.com>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Paul McKenney <paulmck@linux.vnet.ibm.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Ingo Molnar <mingo@kernel.org>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: locking/atomic: Introduce atomic_try_cmpxchg()
Date: Fri, 24 Mar 2017 21:14:39 +0100	[thread overview]
Message-ID: <20170324201439.GY5680@worktop> (raw)
In-Reply-To: <CALCETrUwYUzTk_453WaxOE32RD1i=wBdQUcsrc9OvvtmPtoQ_Q@mail.gmail.com>

On Fri, Mar 24, 2017 at 12:16:11PM -0700, Andy Lutomirski wrote:
> On Fri, Mar 24, 2017 at 11:13 AM, Peter Zijlstra <peterz@infradead.org> wrote:

> > Not to mention we cannot use the C11 atomics in kernel because we want
> > to be able to runtime patch LOCK prefixes when only 1 CPU is available.
> 
> Is this really a show-stopper?  I bet that objtool could be persuaded
> to emit a list of the locations of all those LOCK prefixes.

Ah, but its not _all_ LOCK prefixes. Some are needed even on UP, because
against hardware instead of other CPUs. Or again hypervisor instead of
other vCPU.

  parent reply	other threads:[~2017-03-24 20:15 UTC|newest]

Thread overview: 37+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-03-24 12:44 locking/atomic: Introduce atomic_try_cmpxchg() Dmitry Vyukov
2017-03-24 14:21 ` Peter Zijlstra
2017-03-24 14:23   ` Dmitry Vyukov
2017-03-24 16:41   ` Peter Zijlstra
2017-03-24 16:54     ` Andy Lutomirski
2017-03-24 17:23       ` Peter Zijlstra
2017-03-24 17:51         ` Dmitry Vyukov
2017-03-24 18:08           ` Peter Zijlstra
2017-03-24 18:13             ` Peter Zijlstra
2017-03-24 19:16               ` Andy Lutomirski
2017-03-24 19:20                 ` Linus Torvalds
2017-03-24 19:27                   ` Andy Lutomirski
2017-03-24 20:15                   ` Peter Zijlstra
2017-03-24 20:14                 ` Peter Zijlstra [this message]
2017-03-24 20:21                   ` Andy Lutomirski
2017-03-24 18:16             ` Dmitry Vyukov
2017-03-24 18:00         ` Peter Zijlstra
2017-03-24 18:04           ` Peter Zijlstra
2017-03-24 18:45         ` Andy Lutomirski
2017-03-24 19:17           ` Linus Torvalds
2017-03-24 21:23             ` Peter Zijlstra
2017-03-25  7:51               ` Peter Zijlstra
2017-03-25 18:00                 ` Linus Torvalds
2017-03-25 18:20                   ` Peter Zijlstra
2017-03-25 18:28                     ` Linus Torvalds
2017-03-25 18:34                       ` Linus Torvalds
2017-03-25 21:13                         ` Peter Zijlstra
2017-03-25 22:08                           ` Linus Torvalds
2017-03-27  9:48                             ` Peter Zijlstra
2017-03-24 20:22           ` Peter Zijlstra
2017-03-24 20:27             ` Andy Lutomirski
2017-03-24 21:07               ` Peter Zijlstra
2017-03-24 19:08         ` Linus Torvalds
2017-03-24 20:46           ` Peter Zijlstra
2017-03-24 20:58             ` Linus Torvalds
2017-03-27 12:16 ` Peter Zijlstra
2017-03-27 13:45   ` Dmitry Vyukov

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