Kiyoshi Ueda wrote: > This patch disables interrupt when taking map_lock to prevent > needless lockdep warnings in request-based dm. > > request-based dm takes map_lock after taking queue_lock with > disabling interrupt: > spin_lock_irqsave(queue_lock) > q->request_fn() == dm_request_fn() > => dm_get_table() > => read_lock(map_lock) > while queue_lock could be taken in interrupt context. > > So lockdep warns that a deadlock can happen: > write_lock(map_lock) > <interrupt> > spin_lock_irqsave(queue_lock) > q->request_fn() == dm_request_fn() > => dm_get_table() > => read_lock(map_lock) > > Currently there is no such code path in request-based dm where > q->request_fn() is called from interrupt context, so no such deadlock > happens. > But such warning messages confuse users, so prevent them by disabling > interrupt when taking map_lock. > > > Signed-off-by: Kiyoshi Ueda <k-ueda@xxxxxxxxxxxxx> > Signed-off-by: Jun'ichi Nomura <j-nomura@xxxxxxxxxxxxx> Acked-by: Hannes Reinecke <hare@xxxxxxx> Cheers, Hannes -- Dr. Hannes Reinecke zSeries & Storage hare@xxxxxxx +49 911 74053 688 SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 Nürnberg GF: Markus Rex, HRB 16746 (AG Nürnberg) -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
