Neil Horman ca99ca14c9 netpoll: protect napi_poll and poll_controller during dev_[open|close] ... Ivan Vercera was recently backporting commit 9c13cb8bb4 to a RHEL kernel, and I noticed that, while this patch protects the tg3 driver from having its ndo_poll_controller routine called during device initalization, it does nothing for the driver during shutdown. I.e. it would be entirely possible to have the ndo_poll_controller method (or subsequently the ndo_poll) routine called for a driver in the netpoll path on CPU A while in parallel on CPU B, the ndo_close or ndo_open routine could be called. Given that the two latter routines tend to initizlize and free many data structures that the former two rely on, the result can easily be data corruption or various other crashes. Furthermore, it seems that this is potentially a problem with all net drivers that support netpoll, and so this should ideally be fixed in a common path. As Ben H Pointed out to me, we can't preform dev_open/dev_close in atomic context, so I've come up with this solution. We can use a mutex to sleep in open/close paths and just do a mutex_trylock in the napi poll path and abandon the poll attempt if we're locked, as we'll just retry the poll on the next send anyway. I've tested this here by flooding netconsole with messages on a system whos nic driver I modfied to periodically return NETDEV_TX_BUSY, so that the netpoll tx workqueue would be forced to send frames and poll the device. While this was going on I rapidly ifdown/up'ed the interface and watched for any problems. I've not found any. Signed-off-by: Neil Horman <nhorman@tuxdriver.com> CC: Ivan Vecera <ivecera@redhat.com> CC: "David S. Miller" <davem@davemloft.net> CC: Ben Hutchings <bhutchings@solarflare.com> CC: Francois Romieu <romieu@fr.zoreil.com> CC: Eric Dumazet <eric.dumazet@gmail.com> Signed-off-by: David S. Miller <davem@davemloft.net>		2013-02-06 15:45:03 -05:00
..
acpi	PCI changes for the v3.8 merge window:	2012-12-13 12:14:47 -08:00
asm-generic	Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/geert/linux-m68k	2013-01-23 13:31:15 -08:00
clocksource
crypto
drm	Merge branch 'drm-intel-fixes' of git://people.freedesktop.org/~danvet/drm-intel	2013-01-11 07:52:48 +10:00
keys
linux	netpoll: protect napi_poll and poll_controller during dev_[open|close]	2013-02-06 15:45:03 -05:00
math-emu
media
memory
misc
net	tcp: remove Appropriate Byte Count support	2013-02-05 14:51:16 -05:00
pcmcia
ras
rdma	UAPI: Remove empty Kbuild files	2013-01-02 17:36:10 -08:00
rxrpc
scsi	SCSI misc on 20121212	2012-12-13 19:20:31 -08:00
sound	Merge remote-tracking branch 'asoc/fix/cs4271' into tmp	2013-01-10 12:22:11 +00:00
target	target: Introduce TCM_NO_SENSE	2013-01-10 20:06:08 -08:00
trace	Various bug fixes for ext4. Perhaps the most serious bug fixed is one	2013-01-02 09:57:34 -08:00
uapi	wanrouter: delete now orphaned header content, files/drivers	2013-01-31 19:56:35 -05:00
video	Merge branch 'omap-for-v3.8/fixes-for-merge-window' into omap-for-v3.8/fixes-for-merge-window-v2	2012-12-16 11:28:10 -08:00
xen	Bugfixes:	2012-12-18 12:26:54 -08:00
Kbuild	UAPI: Remove empty Kbuild files	2013-01-02 17:36:10 -08:00