iwlwifi: fix PCI-E transport "inta" race
authorJohannes Berg <johannes.berg@intel.com>
Thu, 19 Jan 2012 16:20:57 +0000 (08:20 -0800)
committerJohn W. Linville <linville@tuxdriver.com>
Tue, 24 Jan 2012 19:47:10 +0000 (14:47 -0500)
commitb49ba04a3a0382e7314d990707c21094c410425a
treedc510fd3cf007d838881539b0a1fab0b92ef2555
parent405385f8ce7a2ed8f82e216d88b5282142e1288b
iwlwifi: fix PCI-E transport "inta" race

When an interrupt comes in, we read the reason
bits and collect them into "trans_pcie->inta".
This happens with the spinlock held. However,
there's a bug resetting this variable -- that
happens after the spinlock has been released.
This means that it is possible for interrupts
to be missed if the reset happens after some
other interrupt reasons were already added to
the variable.

I found this by code inspection, looking for a
reason that we sometimes see random commands
time out. It seems possible that this causes
such behaviour, but I can't say for sure right
now since it happens extremely infrequently on
my test systems.

Cc: stable@vger.kernel.org [3.2]
Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Wey-Yi Guy <wey-yi.w.guy@intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
drivers/net/wireless/iwlwifi/iwl-trans-pcie-rx.c