From: Ben Greear <[email protected]>
Calling napi_disable twice in a row (w/out starting it and/or without
having NAPI active leads to deadlock because napi_disable sets
NAPI_STATE_SCHED and NAPI_STATE_NPSVC when it returns, as far as I
can tell. So, guard this call to napi_disable. I believe the
failure case is something like this:
rmmod ath10k_pci ath10k_core
Firmware crashes before hif_stop is called by the rmmod path
The crash handling logic calls hif_stop
Then rmmod gets around to calling hif_stop, but spins endlessly
in napi_synchronize.
I think one way this could happen is that ath10k_stop checks
for state != ATH10K_STATE_OFF, but STATE_RESTARTING is also
a possibility. That might be how we can have hif_stop called twice
without a hif_start in between. --Ben
Signed-off-by: Ben Greear <[email protected]>
---
* since RFC: Added similar code to ahb
This seems needed back to at least 4.9 kernels.
drivers/net/wireless/ath/ath10k/ahb.c | 9 +++++++--
drivers/net/wireless/ath/ath10k/core.h | 1 +
drivers/net/wireless/ath/ath10k/pci.c | 25 +++++++++++++++++++++++--
3 files changed, 31 insertions(+), 4 deletions(-)
diff --git a/drivers/net/wireless/ath/ath10k/ahb.c b/drivers/net/wireless/ath/ath10k/ahb.c
index da770af..f826c59 100644
--- a/drivers/net/wireless/ath/ath10k/ahb.c
+++ b/drivers/net/wireless/ath/ath10k/ahb.c
@@ -641,6 +641,8 @@ static int ath10k_ahb_hif_start(struct ath10k *ar)
ath10k_dbg(ar, ATH10K_DBG_BOOT, "boot ahb hif start\n");
napi_enable(&ar->napi);
+ ar->napi_enabled = true;
+
ath10k_ce_enable_interrupts(ar);
ath10k_pci_enable_legacy_irq(ar);
@@ -660,8 +662,11 @@ static void ath10k_ahb_hif_stop(struct ath10k *ar)
ath10k_pci_flush(ar);
- napi_synchronize(&ar->napi);
- napi_disable(&ar->napi);
+ if (ar->napi_enabled) {
+ napi_synchronize(&ar->napi);
+ napi_disable(&ar->napi);
+ ar->napi_enabled = false;
+ }
}
static int ath10k_ahb_hif_power_up(struct ath10k *ar)
diff --git a/drivers/net/wireless/ath/ath10k/core.h b/drivers/net/wireless/ath/ath10k/core.h
index 72b4495..c7ba49f 100644
--- a/drivers/net/wireless/ath/ath10k/core.h
+++ b/drivers/net/wireless/ath/ath10k/core.h
@@ -1205,6 +1205,7 @@ struct ath10k {
/* NAPI */
struct net_device napi_dev;
struct napi_struct napi;
+ bool napi_enabled;
struct work_struct stop_scan_work;
diff --git a/drivers/net/wireless/ath/ath10k/pci.c b/drivers/net/wireless/ath/ath10k/pci.c
index 398e413..9131e15 100644
--- a/drivers/net/wireless/ath/ath10k/pci.c
+++ b/drivers/net/wireless/ath/ath10k/pci.c
@@ -1956,6 +1956,7 @@ static int ath10k_pci_hif_start(struct ath10k *ar)
ath10k_dbg(ar, ATH10K_DBG_BOOT, "boot hif start\n");
napi_enable(&ar->napi);
+ ar->napi_enabled = true;
ath10k_pci_irq_enable(ar);
ath10k_pci_rx_post(ar);
@@ -2086,8 +2087,28 @@ static void ath10k_pci_hif_stop(struct ath10k *ar)
ath10k_pci_irq_disable(ar);
ath10k_pci_irq_sync(ar);
ath10k_pci_flush(ar);
- napi_synchronize(&ar->napi);
- napi_disable(&ar->napi);
+
+ /* Calling napi_disable twice in a row (w/out starting it and/or without
+ * having NAPI active leads to deadlock because napi_disable sets
+ * NAPI_STATE_SCHED and NAPI_STATE_NPSVC when it returns, as far as I
+ * can tell. So, guard this call to napi_disable. I believe the
+ * failure case is something like this:
+ * rmmod ath10k_pci ath10k_core
+ * Firmware crashes before hif_stop is called by the rmmod path
+ * The crash handling logic calls hif_stop
+ * Then rmmod gets around to calling hif_stop, but spins endlessly
+ * in napi_synchronize.
+ *
+ * I think one way this could happen is that ath10k_stop checks
+ * for state != ATH10K_STATE_OFF, but STATE_RESTARTING is also
+ * a possibility. That might be how we can have hif_stop called twice
+ * without a hif_start in between. --Ben
+ */
+ if (ar->napi_enabled) {
+ napi_synchronize(&ar->napi);
+ napi_disable(&ar->napi);
+ ar->napi_enabled = false;
+ }
spin_lock_irqsave(&ar_pci->ps_lock, flags);
WARN_ON(ar_pci->ps_wake_refcount > 0);
--
2.4.11