On Fri, May 16, 2014 at 9:59 AM, Rusty Russell <[email protected]> wrote: > Ming Lei <[email protected]> writes: >> When there isn't enough vring descriptor for adding to vq, >> blk-mq will be put as stopped state until some of pending >> descriptors are completed & freed. >> >> Unfortunately, the vq's interrupt may come just before >> blk-mq's BLK_MQ_S_STOPPED flag is set, so the blk-mq will >> still be kept as stopped even though lots of descriptors >> are completed and freed in the interrupt handler. The worst >> case is that all pending descriptors are freed in the >> interrupt handler, and the queue is kept as stopped forever. >> >> This patch fixes the problem by starting/stopping blk-mq >> with holding vq_lock. > > OK, but why the flag? Isn't moving the > blk_mq_start_stopped_hw_queues(vblk->disk->queue, true); > > inside the lock sufficient?
The flag has been removed in v1. I introduced the flag just for avoiding unnecessary calling blk_mq_start_stopped_hw_queues() at most of time, but it isn't a big deal. Thanks, -- Ming Lei -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
