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Subject[PATCH] iwlwifi: don't panic in error path on non-msix systems
From: Shahar S Matityahu <shahar.s.matityahu@intel.com>

The driver uses msix causes-register to handle both msix and non msix
interrupts when performing sync nmi. On devices that do not support
msix this register is unmapped and accessing it causes a kernel panic.

Solve this by differentiating the two cases and accessing the proper
causes-register in each case.

Reported-by: Michal Hocko <mhocko@kernel.org>
Signed-off-by: Shahar S Matityahu <shahar.s.matityahu@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
---
.../net/wireless/intel/iwlwifi/pcie/trans.c | 19 +++++++++++++------
1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/drivers/net/wireless/intel/iwlwifi/pcie/trans.c b/drivers/net/wireless/intel/iwlwifi/pcie/trans.c
index 79c1dc05f948..c4375b868901 100644
--- a/drivers/net/wireless/intel/iwlwifi/pcie/trans.c
+++ b/drivers/net/wireless/intel/iwlwifi/pcie/trans.c
@@ -3644,20 +3644,27 @@ struct iwl_trans *iwl_trans_pcie_alloc(struct pci_dev *pdev,

void iwl_trans_pcie_sync_nmi(struct iwl_trans *trans)
{
+ struct iwl_trans_pcie *trans_pcie = IWL_TRANS_GET_PCIE_TRANS(trans);
unsigned long timeout = jiffies + IWL_TRANS_NMI_TIMEOUT;
+ u32 inta_addr, sw_err_bit;
+
+ if (trans_pcie->msix_enabled) {
+ inta_addr = CSR_MSIX_HW_INT_CAUSES_AD;
+ sw_err_bit = MSIX_HW_INT_CAUSES_REG_SW_ERR;
+ } else {
+ inta_addr = CSR_INT;
+ sw_err_bit = CSR_INT_BIT_SW_ERR;
+ }

iwl_disable_interrupts(trans);
iwl_force_nmi(trans);
while (time_after(timeout, jiffies)) {
- u32 inta_hw = iwl_read32(trans,
- CSR_MSIX_HW_INT_CAUSES_AD);
+ u32 inta_hw = iwl_read32(trans, inta_addr);

/* Error detected by uCode */
- if (inta_hw & MSIX_HW_INT_CAUSES_REG_SW_ERR) {
+ if (inta_hw & sw_err_bit) {
/* Clear causes register */
- iwl_write32(trans, CSR_MSIX_HW_INT_CAUSES_AD,
- inta_hw &
- MSIX_HW_INT_CAUSES_REG_SW_ERR);
+ iwl_write32(trans, inta_addr, inta_hw & sw_err_bit);
break;
}

--
2.20.1
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