Messages in this thread Patch in this message | | | Date | Wed, 01 Feb 2012 13:00:17 -0800 | From | Greg KH <> | Subject | [53/89] iwlwifi: fix PCI-E transport "inta" race |
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3.2-stable review patch. If anyone has any objections, please let me know.
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From: Johannes Berg <johannes.berg@intel.com>
commit b49ba04a3a0382e7314d990707c21094c410425a upstream.
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.
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> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
--- drivers/net/wireless/iwlwifi/iwl-trans-pcie-rx.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)
--- a/drivers/net/wireless/iwlwifi/iwl-trans-pcie-rx.c +++ b/drivers/net/wireless/iwlwifi/iwl-trans-pcie-rx.c @@ -957,11 +957,11 @@ void iwl_irq_tasklet(struct iwl_trans *t } #endif - spin_unlock_irqrestore(&trans->shrd->lock, flags); - /* saved interrupt in inta variable now we can reset trans_pcie->inta */ trans_pcie->inta = 0; + spin_unlock_irqrestore(&trans->shrd->lock, flags); + /* Now service all interrupt bits discovered above. */ if (inta & CSR_INT_BIT_HW_ERR) { IWL_ERR(trans, "Hardware error detected. Restarting.\n");
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