• Vasanthakumar Thiagarajan's avatar
    ath6kl: Fix lockdep warning · 11f6e40d
    Vasanthakumar Thiagarajan authored
    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: default avatarKalle Valo <kvalo@qca.qualcomm.com>
    Signed-off-by: default avatarVasanthakumar Thiagarajan <vthiagar@qca.qualcomm.com>
    Signed-off-by: default avatarKalle Valo <kvalo@qca.qualcomm.com>
    11f6e40d
txrx.c 35.9 KB