netdev - Re: PROBLEM: System call 'sendmsg' of process ospfd (quagga) causes kernel oops

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Message-ID: <20111018100527.GA15383@gondor.apana.org.au>
Date:	Tue, 18 Oct 2011 12:05:27 +0200
From:	Herbert Xu <herbert@...dor.apana.org.au>
To:	Eric Dumazet <eric.dumazet@...il.com>
Cc:	Elmar Vonlanthen <evonlanthen@...il.com>,
	linux-kernel@...r.kernel.org, netdev <netdev@...r.kernel.org>,
	Timo Teräs <timo.teras@....fi>
Subject: Re: PROBLEM: System call 'sendmsg' of process ospfd (quagga)
	causes kernel oops

On Tue, Oct 18, 2011 at 12:01:33PM +0200, Eric Dumazet wrote:
>
> Adding an RCU protected structure to hold hard_header_len /
> needed_headroom / needed_tailroom should be possible, but this adds yet
> another pointer dereference...

I don't think we need RCU here since the problem is simply that
we're using two different values for skb allocations and skb_reserve.

As long as we use one and the same value it should work.  The value
will rarely be incorrect and when it is, automatic reallocation will
occur.

Cheers,
-- 
Email: Herbert Xu <herbert@...dor.apana.org.au>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt
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