| Message ID | 20240524023642.37030-1-quic_bqiang@quicinc.com |
|---|---|
| State | New |
| Headers | show |
| Series | wifi: ath12k: fix race due to setting ATH12K_FLAG_EXT_IRQ_ENABLED too early | expand |
Baochen Qiang <quic_bqiang@quicinc.com> wrote: > Commit 5082b3e3027e ("wifi: ath11k: fix race due to setting > ATH11K_FLAG_EXT_IRQ_ENABLED too early") fixes a race in ath11k > driver. Since ath12k shares the same logic as ath11k, currently > the race also exists in ath12k: in ath12k_pci_ext_irq_enable(), > ATH12K_FLAG_EXT_IRQ_ENABLED is set before NAPI is enabled. > In cases where only one MSI vector is allocated, this results > in a race condition: after ATH12K_FLAG_EXT_IRQ_ENABLED is set > but before NAPI enabled, CE interrupt breaks in. Since IRQ is > shared by CE and data path, ath12k_pci_ext_interrupt_handler() > is also called where we call disable_irq_nosync() to disable > IRQ. Then napi_schedule() is called but it does nothing because > NAPI is not enabled at that time, meaning that > ath12k_pci_ext_grp_napi_poll() will never run, so we have > no chance to call enable_irq() to enable IRQ back. Since IRQ > is shared, all interrupts are disabled and we would finally > get no response from target. > > So port ath11k fix here, this is done by setting > ATH12K_FLAG_EXT_IRQ_ENABLED after all NAPI and IRQ work are > done. With the fix, we are sure that by the time > ATH12K_FLAG_EXT_IRQ_ENABLED is set, NAPI is enabled. > > Note that the fix above also introduce some side effects: > if ath12k_pci_ext_interrupt_handler() breaks in after NAPI > enabled but before ATH12K_FLAG_EXT_IRQ_ENABLED set, nothing > will be done by the handler this time, the work will be > postponed till the next time the IRQ fires. > > This is found during code review. > > Tested-on: WCN7850 hw2.0 PCI WLAN.HMT.1.0.c5-00481-QCAHMTSWPL_V1.0_V2.0_SILICONZ-3 > > Signed-off-by: Baochen Qiang <quic_bqiang@quicinc.com> > Acked-by: Jeff Johnson <quic_jjohnson@quicinc.com> > Signed-off-by: Kalle Valo <quic_kvalo@quicinc.com> Patch applied to ath-next branch of ath.git, thanks. 0a993772e0f0 wifi: ath12k: fix race due to setting ATH12K_FLAG_EXT_IRQ_ENABLED too early
diff --git a/drivers/net/wireless/ath/ath12k/pci.c b/drivers/net/wireless/ath/ath12k/pci.c index ac75e8e3916b..11b95d037051 100644 --- a/drivers/net/wireless/ath/ath12k/pci.c +++ b/drivers/net/wireless/ath/ath12k/pci.c @@ -1107,14 +1107,14 @@ void ath12k_pci_ext_irq_enable(struct ath12k_base *ab) { int i; - set_bit(ATH12K_FLAG_EXT_IRQ_ENABLED, &ab->dev_flags); - for (i = 0; i < ATH12K_EXT_IRQ_GRP_NUM_MAX; i++) { struct ath12k_ext_irq_grp *irq_grp = &ab->ext_irq_grp[i]; napi_enable(&irq_grp->napi); ath12k_pci_ext_grp_enable(irq_grp); } + + set_bit(ATH12K_FLAG_EXT_IRQ_ENABLED, &ab->dev_flags); } void ath12k_pci_ext_irq_disable(struct ath12k_base *ab)
Commit 5082b3e3027e ("wifi: ath11k: fix race due to setting ATH11K_FLAG_EXT_IRQ_ENABLED too early") fixes a race in ath11k driver. Since ath12k shares the same logic as ath11k, currently the race also exists in ath12k: in ath12k_pci_ext_irq_enable(), ATH12K_FLAG_EXT_IRQ_ENABLED is set before NAPI is enabled. In cases where only one MSI vector is allocated, this results in a race condition: after ATH12K_FLAG_EXT_IRQ_ENABLED is set but before NAPI enabled, CE interrupt breaks in. Since IRQ is shared by CE and data path, ath12k_pci_ext_interrupt_handler() is also called where we call disable_irq_nosync() to disable IRQ. Then napi_schedule() is called but it does nothing because NAPI is not enabled at that time, meaning that ath12k_pci_ext_grp_napi_poll() will never run, so we have no chance to call enable_irq() to enable IRQ back. Since IRQ is shared, all interrupts are disabled and we would finally get no response from target. So port ath11k fix here, this is done by setting ATH12K_FLAG_EXT_IRQ_ENABLED after all NAPI and IRQ work are done. With the fix, we are sure that by the time ATH12K_FLAG_EXT_IRQ_ENABLED is set, NAPI is enabled. Note that the fix above also introduce some side effects: if ath12k_pci_ext_interrupt_handler() breaks in after NAPI enabled but before ATH12K_FLAG_EXT_IRQ_ENABLED set, nothing will be done by the handler this time, the work will be postponed till the next time the IRQ fires. This is found during code review. Tested-on: WCN7850 hw2.0 PCI WLAN.HMT.1.0.c5-00481-QCAHMTSWPL_V1.0_V2.0_SILICONZ-3 Signed-off-by: Baochen Qiang <quic_bqiang@quicinc.com> --- drivers/net/wireless/ath/ath12k/pci.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) base-commit: fae0804439b5833308ab7d8563c643edb0fa174c