From: Borislav Petkov <bp@amd64.org>
To: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: "Srivatsa S. Bhat" <srivatsa.bhat@linux.vnet.ibm.com>,
bp@amd64.org, tony.luck@intel.com, tglx@linutronix.de,
mingo@elte.hu, hpa@zytor.com, x86@kernel.org,
linux-edac@vger.kernel.org, linux-kernel@vger.kernel.org,
marcos.mage@gmail.com, prasad@linux.vnet.ibm.com
Subject: Re: [PATCH] x86, mce: Fix rcu splat in drain_mce_log_buffer()
Date: Mon, 6 Feb 2012 17:18:02 +0100 [thread overview]
Message-ID: <20120206161802.GC31237@aftab> (raw)
In-Reply-To: <20120113214435.GC2909@linux.vnet.ibm.com>
On Fri, Jan 13, 2012 at 01:44:35PM -0800, Paul E. McKenney wrote:
> Looks good to me, but I do need to defer to people who know this code
> better than do I. The key thing that (from what I can see) makes
> rcu_dereference() unnecessary is that the smp_rmb() used in conjunction
> with polling the .finished field takes care of ordering.
Right, this was me trying hard not to screw up touching mcelog.next,
thus trying to use the rcu_dereference_index_check() primitive without
thinking it through too much. But you're right, I'm polling the
->finished field 4 times (totally arbitrary, btw) which should suffice
while the mce_log() routine above writes those entries.
Although, the question still remains, since mce_log() accesses
mcelog.next through the rcu_dereference_index_check() primitive,
shouldn't I do it the same way?
Thanks.
--
Regards/Gruss,
Boris.
Advanced Micro Devices GmbH
Einsteinring 24, 85609 Dornach
GM: Alberto Bozzo
Reg: Dornach, Landkreis Muenchen
HRB Nr. 43632 WEEE Registernr: 129 19551
next prev parent reply other threads:[~2012-02-06 16:18 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-01-11 14:24 [PATCH] x86, mce: Fix rcu splat in drain_mce_log_buffer() Srivatsa S. Bhat
2012-01-11 16:11 ` Paul E. McKenney
2012-01-13 12:28 ` Srivatsa S. Bhat
2012-01-13 21:44 ` Paul E. McKenney
2012-01-26 16:02 ` Srivatsa S. Bhat
2012-02-06 16:18 ` Borislav Petkov [this message]
2012-02-12 17:41 ` Paul E. McKenney
2012-02-16 10:17 ` Borislav Petkov
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