On 18/2/23 09:08, Bart Van Assche wrote: > Avoid that the following race can occur: > > blk_cleanup_queue() blkcg_print_blkgs() > spin_lock_irq(lock) (1) spin_lock_irq(blkg->q->queue_lock) (2,5) > q->queue_lock = &q->__queue_lock (3) > spin_unlock_irq(lock) (4) > spin_unlock_irq(blkg->q->queue_lock) (6) > > (1) take driver lock; > (2) busy loop for driver lock; > (3) override driver lock with internal lock; > (4) unlock driver lock; > (5) can take driver lock now; > (6) but unlock internal lock. > > This change is safe because only the SCSI core and the NVME core keep > a reference on a request queue after having called blk_cleanup_queue(). > Neither driver accesses any of the removed data structures between its > blk_cleanup_queue() and blk_put_queue() calls. > > Reported-by: Joseph Qi <joseph.qi@xxxxxxxxxxxxxxxxx> > Signed-off-by: Bart Van Assche <bart.vanassche@xxxxxxx> > Cc: Jan Kara <jack@xxxxxxxx> Looks good. Reviewed-by: Joseph Qi <joseph.qi@xxxxxxxxxxxxxxxxx>
