ath6kl: Fix lockdep warning
The following is the lockdep warning which detects possible
deadlock condition with the way ar->lock and ar->list_lock
are being used.
(&(&ar->lock)->rlock){+.-...}, at: [<ffffffffa0492d13>] ath6kl_indicate_tx_activity+0x83/0x110 [ath6kl]
but this lock took another, SOFTIRQ-unsafe lock in the past:
(&(&ar->list_lock)->rlock){+.+...}
and interrupts could create inverse lock ordering between them.
other info that might help us debug this:
Possible interrupt unsafe locking scenario:
CPU0 CPU1
---- ----
lock(&(&ar->list_lock)->rlock);
local_irq_disable();
lock(&(&ar->lock)->rlock);
lock(&(&ar->list_lock)->rlock);
<Interrupt>
lock(&(&ar->lock)->rlock);
*** DEADLOCK ***
softirqs have to be disabled when acquiring ar->list_lock to avoid
the above deadlock condition. When the above warning printed the
interface is still up and running without issue.
Reported-by: Kalle Valo <kvalo@qca.qualcomm.com>
Signed-off-by: Vasanthakumar Thiagarajan <vthiagar@qca.qualcomm.com>
Signed-off-by: Kalle Valo <kvalo@qca.qualcomm.com>
diff --git a/drivers/net/wireless/ath/ath6kl/main.c b/drivers/net/wireless/ath/ath6kl/main.c
index 23da82e..f9410e4 100644
--- a/drivers/net/wireless/ath/ath6kl/main.c
+++ b/drivers/net/wireless/ath/ath6kl/main.c
@@ -1046,15 +1046,15 @@
{
struct ath6kl_vif *vif;
- spin_lock(&ar->list_lock);
+ spin_lock_bh(&ar->list_lock);
if (list_empty(&ar->vif_list)) {
- spin_unlock(&ar->list_lock);
+ spin_unlock_bh(&ar->list_lock);
return NULL;
}
vif = list_first_entry(&ar->vif_list, struct ath6kl_vif, list);
- spin_unlock(&ar->list_lock);
+ spin_unlock_bh(&ar->list_lock);
return vif;
}