From: Johannes Berg <johannes@sipsolutions.net>
To: netdev <netdev@vger.kernel.org>
Subject: RPS vs. hard-irq-context netif_rx()
Date: Fri, 30 Jul 2010 15:03:47 +0200 [thread overview]
Message-ID: <1280495027.3710.13.camel@jlt3.sipsolutions.net> (raw)
I got the following on a kvm instance I use for testing:
[ 51.358803] WARNING: at kernel/lockdep.c:2327 trace_hardirqs_on_caller+0x167/0x200()
[ 51.360210] Hardware name: Bochs
[ 51.360210] Modules linked in:
[ 51.360210] Pid: 1546, comm: dhclient3 Tainted: G W 2.6.35-rc6-wl+ #588
[ 51.360210] Call Trace:
[ 51.360210] <IRQ> [<ffffffff8104e87f>] warn_slowpath_common+0x7f/0xc0
[ 51.360210] [<ffffffff8104e8da>] warn_slowpath_null+0x1a/0x20
[ 51.360210] [<ffffffff81087977>] trace_hardirqs_on_caller+0x167/0x200
[ 51.360210] [<ffffffff81087a1d>] trace_hardirqs_on+0xd/0x10
[ 51.360210] [<ffffffff81056ade>] local_bh_enable+0x9e/0x130
[ 51.360210] [<ffffffff8139fa82>] netif_rx+0xc2/0x250
[ 51.360210] [<ffffffff813146d7>] ei_receive+0x1b7/0x2c0
[ 51.360210] [<ffffffff81314ca2>] __ei_interrupt+0x282/0x360
[ 51.360210] [<ffffffff81314dce>] ei_interrupt+0xe/0x10
[ 51.360210] [<ffffffff810abe85>] handle_IRQ_event+0x85/0x300
[ 51.360210] [<ffffffff810aead5>] handle_level_irq+0x95/0x120
[ 51.360210] [<ffffffff81005a12>] handle_irq+0x22/0x30
[ 51.360210] [<ffffffff814394b3>] do_IRQ+0x73/0xf0
...
The reason seems to be that
* RCU_TREE uses local_bh_disable/enable
* CONFIG_RPS uses RCU within netif_rx()
* the driver I'm using calls netif_rx() within the irq context
So .. where's the bug? I'd point to CONFIG_RPS since it's newest.
johannes
next reply other threads:[~2010-07-30 13:02 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-07-30 13:03 Johannes Berg [this message]
2010-07-30 13:21 ` RPS vs. hard-irq-context netif_rx() Johannes Berg
2010-08-17 11:52 ` Luca Tettamanti
2010-08-17 14:54 ` Eric Dumazet
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