af_packet: Don't use skb after dev_queue_xmit()
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From: Jarek Poplawski on 7 Jan 2010 13:00 On Thu, Jan 07, 2010 at 10:03:51AM -0500, Michael Breuer wrote: > On 1/7/2010 3:21 AM, Jarek Poplawski wrote: > >On Thu, Jan 07, 2010 at 02:55:20AM -0500, Michael Breuer wrote: > >>Unless I misread the code, I think that in some cases e skb is actually > >>freed if the cfq (among others perhaps) scheduler returns an error on > >>enqueue (flow control perhaps). Thus with alternative 1, it is possible > >>that the skb is acted upon after being freed - this would be consistent > >>with the DMAR errors I saw. > >I can't see your point: could you give some scenario? > > > >Jarek P. > With NET_CLS_ACT set, net_dev_enqueue can return an error after > freeing the skb. Alternative 1 disregards the error and assumes the > skb is still valid. The original code and alternative 2 exit the > loop assuming the skb has been freed. Not exactly: alternative 1 disregards the error, and tries to send next skbs if the message was longer. After consuming all the message it returns without err code (at least wrt. dev_queue_xmit). This is quite often practice to skip dev_queue_xmit() return (try to grep in net\). It should never touch any part of an earlier sent skb. Jarek P. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Jarek Poplawski on 7 Jan 2010 13:10 On Thu, Jan 07, 2010 at 10:05:37AM -0500, Michael Breuer wrote: > Bad news - crashed about an hour after I wrote this email - under > load - same crash as before. Network watchdog... lots of attempts to > reset the adapter... then hw watchdog rebooted the system. It's a pity. Anyway, I'd be still interested in CONFIG_PACKET_MMAP off if you find time. Jarek P. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Jarek Poplawski on 7 Jan 2010 13:20 On Thu, Jan 07, 2010 at 06:56:10PM +0100, Jarek Poplawski wrote: > [...] (try to grep in net\). [...] Did I say "net\"?! Extremely sorry! ;-) Jarek P. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Michael Breuer on 7 Jan 2010 13:30 On 1/7/2010 1:01 PM, Jarek Poplawski wrote: > On Thu, Jan 07, 2010 at 10:05:37AM -0500, Michael Breuer wrote: > >> Bad news - crashed about an hour after I wrote this email - under >> load - same crash as before. Network watchdog... lots of attempts to >> reset the adapter... then hw watchdog rebooted the system. >> > It's a pity. Anyway, I'd be still interested in CONFIG_PACKET_MMAP off > if you find time. > > Jarek P. > Ok - any particular patch set to try with? I'm going to start with a clean tree using the latest 2.6.32 from git (tried 2.6.33-rc3, but can't get a usable console... will look at that later.) -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
From: Jarek Poplawski on 7 Jan 2010 13:40
On Thu, Jan 07, 2010 at 01:19:41PM -0500, Michael Breuer wrote: > On 1/7/2010 1:01 PM, Jarek Poplawski wrote: > >On Thu, Jan 07, 2010 at 10:05:37AM -0500, Michael Breuer wrote: > >>Bad news - crashed about an hour after I wrote this email - under > >>load - same crash as before. Network watchdog... lots of attempts to > >>reset the adapter... then hw watchdog rebooted the system. > >It's a pity. Anyway, I'd be still interested in CONFIG_PACKET_MMAP off > >if you find time. > > > >Jarek P. > Ok - any particular patch set to try with? I'm going to start with a > clean tree using the latest 2.6.32 from git (tried 2.6.33-rc3, but > can't get a usable console... will look at that later.) My "Berck E. Nash" and Stephen's "pskb_may_pull" sky2 patches. (BTW, could you remind if it worked any better with 2.6.31 or earlier?) Jarek P. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo(a)vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/ |