From: Peter Zijlstra <peterz@infradead.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Jan Stancek <jstancek@redhat.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Srikar Dronamraju <srikar@linux.vnet.ibm.com>,
Davidlohr Bueso <davidlohr@hp.com>,
Ingo Molnar <mingo@kernel.org>,
Larry Woodman <lwoodman@redhat.com>
Subject: Re: [PATCH] futex: avoid race between requeue and wake
Date: Tue, 8 Apr 2014 20:13:05 +0200 [thread overview]
Message-ID: <20140408181305.GT10526@twins.programming.kicks-ass.net> (raw)
In-Reply-To: <CA+55aFyfKOv59hptv9rEcf31X5O8s26z+S8f-MchM1C0WtXx3A@mail.gmail.com>
On Tue, Apr 08, 2014 at 10:33:55AM -0700, Linus Torvalds wrote:
> Hmm. And let's think about that powerpc race, where "spin_is_locked()"
> can be false when somebody is waiting to get the lock..
Right; so in the original discussion I never really got to why that is a
problem. A pending waiter cannot modify the wait list, so either we see
the current holder, or we see a stable list.
So I had to hop on a plane while that discussion was happening and while
I did briefly task to Davidlohr in Napa his explanation didn't stick in
my jet-leg addled brain.
Afterwards the discussion got lost in the pile of unread mail.
I'll go re-read that discussion and look up this thread to see if
things will start to make sense.
next prev parent reply other threads:[~2014-04-08 18:13 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-04-08 8:47 Jan Stancek
2014-04-08 16:20 ` Linus Torvalds
2014-04-08 17:03 ` Jan Stancek
2014-04-08 17:33 ` Linus Torvalds
2014-04-08 18:13 ` Peter Zijlstra [this message]
2014-04-08 18:53 ` Linus Torvalds
2014-04-08 21:02 ` Jan Stancek
2014-04-08 22:30 ` Linus Torvalds
2014-04-09 2:19 ` Davidlohr Bueso
2014-04-09 5:41 ` Peter Zijlstra
2014-04-09 5:51 ` Mike Galbraith
2014-04-09 11:46 ` Jan Stancek
2014-04-09 15:12 ` Linus Torvalds
2014-04-09 19:03 ` Davidlohr Bueso
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