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From: Oliver Hartkopp <socketcan-fJ+pQTUTwRTk1uMJSBkQmQ@public•gmane.org>
To: David Miller <davem-fT/PcQaiUtIeIZ0/mPfg9Q@public•gmane.org>
Cc: socketcan-core-0fE9KPoRgkgATYTw5x5z8w@public•gmane.org,
	netdev-u79uwXL29TY76Z2rM5mHXA@public•gmane.org,
	patrick.ohly-ral2JQCrhuEAvxtiuMwx3w@public•gmane.org,
	eric.dumazet-Re5JQEeQqe8AvxtiuMwx3w@public•gmane.org
Subject: Re: [PATCH] can-raw: Fix skb_orphan_try handling
Date: Sun, 01 Aug 2010 12:50:16 +0200	[thread overview]
Message-ID: <4C555168.3090800@hartkopp.net> (raw)
In-Reply-To: <20100801.010337.68133932.davem-fT/PcQaiUtIeIZ0/mPfg9Q@public.gmane.org>

On 01.08.2010 10:03, David Miller wrote:
> From: Oliver Hartkopp <socketcan-fJ+pQTUTwRTk1uMJSBkQmQ@public•gmane.org>
> Date: Fri, 30 Jul 2010 11:44:27 +0200
> 
>> Hello Eric, hello Patrick,
>>
>> Commit fc6055a5ba31e2c14e36e8939f9bf2b6d586a7f5 (net: Introduce
>> skb_orphan_try()) allows an early orphan of the skb and takes care on
>> tx timestamping, which needs the sk-reference in the skb on driver level.
>> So does the can-raw socket, which has not been taken into account here.
>>
>> The patch below adds a 'prevent_sk_orphan' bit in the skb tx shared info,
>> which fixes the problem discovered by Matthias Fuchs here:
>>
>>       http://marc.info/?t=128030411900003&r=1&w=2
> 
> Your patch sets this new value, but I never see it getting tested anywhere.
> 
> How does this work?


The flags are tested all together in skb_orphan_try() ...

See at

http://git.kernel.org/?p=linux/kernel/git/davem/net-next-2.6.git;a=commitdiff;h=fc6055a5ba31e2c14e36e8939f9bf2b6d586a7f5

+/*
+ * Try to orphan skb early, right before transmission by the device.
+ * We cannot orphan skb if tx timestamp is requested, since
+ * drivers need to call skb_tstamp_tx() to send the timestamp.
+ */
+static inline void skb_orphan_try(struct sk_buff *skb)
+{
+       if (!skb_tx(skb)->flags)
+               skb_orphan(skb);
+}

So my patch just added a new bit that's tested here but does not touch the
rest of the tx timestamp bits that are checked at this place.

Regards,
Oliver

  parent reply	other threads:[~2010-08-01 10:50 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2010-07-30  9:44 [PATCH] can-raw: Fix skb_orphan_try handling Oliver Hartkopp
2010-08-01  8:03 ` David Miller
     [not found]   ` <20100801.010337.68133932.davem-fT/PcQaiUtIeIZ0/mPfg9Q@public.gmane.org>
2010-08-01 10:50     ` Oliver Hartkopp [this message]
2010-08-03  7:30       ` David Miller
     [not found]         ` <20100803.003056.216763358.davem-fT/PcQaiUtIeIZ0/mPfg9Q@public.gmane.org>
2010-08-03 15:22           ` Oliver Hartkopp
2010-08-03 16:14             ` Patrick Ohly
     [not found]               ` <1280852081.3266.834.camel-/oqbx4SGF9pV+x+AlpbFz62pdiUAq4bhAL8bYrjMMd8@public.gmane.org>
2010-08-03 17:11                 ` Oliver Hartkopp
2010-08-03 17:33                   ` Patrick Ohly
     [not found]                     ` <1280856828.3266.839.camel-/oqbx4SGF9pV+x+AlpbFz62pdiUAq4bhAL8bYrjMMd8@public.gmane.org>
2010-08-03 17:50                       ` Oliver Hartkopp
2010-08-03 23:28                         ` David Miller

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