From: Eric Dumazet <eric.dumazet@gmail.com>
To: Herbert Xu <herbert@gondor.apana.org.au>
Cc: "Elmar Vonlanthen" <evonlanthen@gmail.com>,
linux-kernel@vger.kernel.org, netdev <netdev@vger.kernel.org>,
"Timo Teräs" <timo.teras@iki.fi>
Subject: Re: PROBLEM: System call 'sendmsg' of process ospfd (quagga) causes kernel oops
Date: Tue, 18 Oct 2011 12:23:43 +0200 [thread overview]
Message-ID: <1318933423.2657.44.camel@edumazet-HP-Compaq-6005-Pro-SFF-PC> (raw)
In-Reply-To: <20111018100527.GA15383@gondor.apana.org.au>
Le mardi 18 octobre 2011 à 12:05 +0200, Herbert Xu a écrit :
> 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.
>
You're right, if reallocations are OK in all paths.
We'll need to change LL_RESERVED_SPACE() / LL_RESERVED_SPACE_EXTRA() /
LL_ALLOCATED_SPACE() macros and provide the [read once] values, instead
of a [read once] pointer to values.
Thats a bit complex change, but doable.
next prev parent reply other threads:[~2011-10-18 10:23 UTC|newest]
Thread overview: 31+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <CA+0Zf5Be5JUSvssH9CrDQq=jtETZr=veAPC7jriM8B-FZKbbpg@mail.gmail.com>
2011-10-14 14:57 ` PROBLEM: System call 'sendmsg' of process ospfd (quagga) causes kernel oops Eric Dumazet
2011-10-17 7:16 ` Elmar Vonlanthen
2011-10-18 2:30 ` Eric Dumazet
2011-10-18 9:34 ` Herbert Xu
2011-10-18 10:01 ` Eric Dumazet
2011-10-18 10:05 ` Herbert Xu
2011-10-18 10:23 ` Eric Dumazet [this message]
2011-10-18 10:45 ` Herbert Xu
2011-10-18 11:37 ` Eric Dumazet
2011-10-18 11:49 ` Herbert Xu
2011-10-18 12:56 ` Eric Dumazet
2011-10-18 13:45 ` Herbert Xu
2011-10-19 7:09 ` David Miller
2011-10-19 7:18 ` Eric Dumazet
2011-10-19 7:30 ` David Miller
2011-10-19 7:52 ` Eric Dumazet
2011-10-19 8:02 ` David Miller
2011-10-19 8:08 ` Herbert Xu
2011-10-20 9:30 ` David Miller
2011-10-20 9:35 ` Herbert Xu
2011-10-20 20:21 ` David Miller
2011-10-25 11:54 ` Herbert Xu
2011-10-26 3:12 ` David Miller
2011-11-18 12:18 ` [0/6] Replace LL_ALLOCATED_SPACE to allow needed_headroom adjustment Herbert Xu
2011-11-18 12:20 ` [PATCH 2/6] ipv6: Remove all uses of LL_ALLOCATED_SPACE Herbert Xu
2011-11-18 12:20 ` [PATCH 3/6] net: " Herbert Xu
2011-11-18 12:20 ` [PATCH 1/6] ipv4: " Herbert Xu
2011-11-18 12:20 ` [PATCH 4/6] net: Remove LL_ALLOCATED_SPACE Herbert Xu
2011-11-18 12:20 ` [PATCH 5/6] packet: Add needed_tailroom to packet_sendmsg_spkt Herbert Xu
2011-11-18 12:20 ` [PATCH 6/6] ip_gre: Set needed_headroom dynamically again Herbert Xu
2011-11-18 20:01 ` [0/6] Replace LL_ALLOCATED_SPACE to allow needed_headroom adjustment David Miller
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