From: Matt Mackall <mpm@selenic.com>
To: Herbert Xu <herbert@gondor.apana.org.au>
Cc: "David S. Miller" <davem@davemloft.net>,
netdev@vger.kernel.org, Matt Carlson <mcarlson@broadcom.com>
Subject: Re: netpoll + xmit_lock == deadlock
Date: Wed, 29 Jul 2009 14:07:58 -0500 [thread overview]
Message-ID: <1248894478.4545.2822.camel@calx> (raw)
In-Reply-To: <20090729073523.GA4515@gondor.apana.org.au>
On Wed, 2009-07-29 at 15:35 +0800, Herbert Xu wrote:
> Hi:
>
> While working on TX mitigiation, I noticed that while netpoll
> takes care to avoid recursive dead locks on the NAPI path, it
> has no protection against the TX path when calling the poll
> function.
>
> So if a driver is in the TX path, and a printk occurs, then a
> recursive dead lock can occur if that driver tries to take the
> xmit lock in its poll function to clean up descriptors.
>
> Fortunately not a lot of drivers do this but at least some are
> vulnerable to it, e.g., tg3.
>
> So we need to make it very clear that the poll function must
> not take any locks or they must use try_lock if the driver is
> to support netpoll.
What do you propose?
--
http://selenic.com : development and support for Mercurial and Linux
next prev parent reply other threads:[~2009-07-29 19:08 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-07-29 7:35 netpoll + xmit_lock == deadlock Herbert Xu
2009-07-29 19:07 ` Matt Mackall [this message]
2009-07-29 19:43 ` Neil Horman
2009-07-29 21:48 ` Matt Mackall
2009-07-29 23:15 ` Neil Horman
2009-07-29 23:17 ` Herbert Xu
2009-07-30 1:02 ` Neil Horman
2009-07-31 1:27 ` Herbert Xu
2009-07-29 22:38 ` Herbert Xu
2009-07-30 1:06 ` Neil Horman
2009-07-31 1:30 ` Herbert Xu
2009-07-31 12:56 ` Neil Horman
2009-07-31 13:02 ` Herbert Xu
2009-07-31 18:09 ` Neil Horman
2009-08-02 20:07 ` David Miller
2009-08-03 12:05 ` Ben Hutchings
2009-08-03 19:15 ` David Miller
2009-08-03 19:59 ` Matt Mackall
2009-08-04 4:19 ` David Miller
2009-08-04 6:48 ` Herbert Xu
2009-08-04 0:15 ` Herbert Xu
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