On 11/01/2011 01:08 PM, Vasanthakumar Thiagarajan wrote:
> 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@xxxxxxxxxxxxxxxx>
> Signed-off-by: Vasanthakumar Thiagarajan <vthiagar@xxxxxxxxxxxxxxxx>
Thanks, applied.
Kalle
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