From b49ba04a3a0382e7314d990707c21094c410425a Mon Sep 17 00:00:00 2001 From: Johannes Berg Date: Thu, 19 Jan 2012 08:20:57 -0800 Subject: [PATCH] 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 Signed-off-by: Wey-Yi Guy Signed-off-by: John W. Linville --- drivers/net/wireless/iwlwifi/iwl-trans-pcie-rx.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/drivers/net/wireless/iwlwifi/iwl-trans-pcie-rx.c b/drivers/net/wireless/iwlwifi/iwl-trans-pcie-rx.c index 752493f00406..65d1f05007be 100644 --- a/drivers/net/wireless/iwlwifi/iwl-trans-pcie-rx.c +++ b/drivers/net/wireless/iwlwifi/iwl-trans-pcie-rx.c @@ -972,11 +972,11 @@ void iwl_irq_tasklet(struct iwl_trans *trans) } #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");