From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Anton Blanchard <anton@samba.org>
Cc: jkenisto@us.ibm.com, paulus@samba.org, linuxppc-dev@lists.ozlabs.org
Subject: Re: [PATCH] powerpc/nvram: Add spinlock to oops_to_nvram to prevent oops in compression code.
Date: Thu, 01 Dec 2011 13:11:12 +1100 [thread overview]
Message-ID: <1322705472.3729.11.camel@pasglop> (raw)
In-Reply-To: <20111201124645.24c6e54f@kryten>
On Thu, 2011-12-01 at 12:46 +1100, Anton Blanchard wrote:
> When issuing a system reset we almost always oops in the oops_to_nvram
> code because multiple CPUs are using the deflate work area. Add a
> spinlock to protect it.
>
> To play it safe I'm using trylock to avoid locking up if the NVRAM
> code oopses. This means we might miss multiple CPUs oopsing at exactly
> the same time but I think it's best to play it safe for now. Once we
> are happy with the reliability we can change it to a full spinlock.
How would we miss ?
trylock does loop on stwcx. failure, it doesn't loop if the lock is
-taken-, so if the lock is only used for actually dealing with the oops
the only "miss" is because somebody already got it... or am I missing
something ?
Cheers,
Ben.
next prev parent reply other threads:[~2011-12-01 2:11 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-12-01 1:46 [PATCH] powerpc/nvram: Add spinlock to oops_to_nvram to prevent oops in compression code Anton Blanchard
2011-12-01 2:11 ` Benjamin Herrenschmidt [this message]
2011-12-01 2:26 ` Anton Blanchard
2011-12-02 1:37 ` Jim Keniston
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