From: "Holger Hoffstätte" <holger.hoffstaette@googlemail.com>
To: linux-btrfs@vger.kernel.org
Subject: Re: [PATCH] Btrfs: fix race when reusing stale extent buffers that leads to BUG_ON
Date: Thu, 23 Apr 2015 13:53:22 +0000 (UTC) [thread overview]
Message-ID: <pan.2015.04.23.13.53.22@googlemail.com> (raw)
In-Reply-To: 5538F70C.5040004@suse.com
On Thu, 23 Apr 2015 14:43:40 +0100, Filipe Manana wrote:
> I don't think a lock followed by unlock without nothing in between (be
> it a spinlock, mutex, or any other kind of lock) will be seen by the
> compiler as a nop. Pretty sure I've seen this pattern being done in the
No, I didn't say they would - that would be wrong. I just found it odd,
that's all.
> kernel and in many other places as mechanism to wait for something.
I also completely forgot that spinlocks disable preemption, since
otherwise nothing would really work. That's the real reason why
any of this works. Well, that and the refcount==2 thing.
Cool! Thanks!
Holger
next prev parent reply other threads:[~2015-04-23 13:53 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-04-23 10:28 [PATCH] Btrfs: fix race when reusing stale extent buffers that leads to BUG_ON Filipe Manana
2015-04-23 12:16 ` Holger Hoffstätte
2015-04-23 12:34 ` Filipe Manana
2015-04-23 13:22 ` Holger Hoffstätte
2015-04-23 13:43 ` Filipe Manana
2015-04-23 13:53 ` Holger Hoffstätte [this message]
2015-04-24 16:08 ` Filipe Manana
2015-05-12 13:04 ` David Sterba
2015-05-07 16:19 ` David Sterba
2015-05-07 19:30 ` Chris Mason
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