Reduce the number of return statements from three to one. Reduce the number of spin_unlock(&this_hctx->lock) calls from two to one. Fix a misleading comment: since blk-mq-tag.c always uses wake_up_all() other waiters are woken up whether or not the current hctx is removed from the wait list. This patch does not change any functionality.
Signed-off-by: Bart Van Assche <[email protected]> Cc: Christoph Hellwig <[email protected]> Cc: Omar Sandoval <[email protected]> Cc: Hannes Reinecke <[email protected]> Cc: Johannes Thumshirn <[email protected]> --- block/blk-mq.c | 41 +++++++++++++++-------------------------- 1 file changed, 15 insertions(+), 26 deletions(-) diff --git a/block/blk-mq.c b/block/blk-mq.c index 7f290a91a612..26fec4dfa40f 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -1039,6 +1039,11 @@ static bool blk_mq_mark_tag_wait(struct blk_mq_hw_ctx **hctx, if (!shared_tags) { if (!test_bit(BLK_MQ_S_SCHED_RESTART, &this_hctx->state)) set_bit(BLK_MQ_S_SCHED_RESTART, &this_hctx->state); + ret = blk_mq_get_driver_tag(rq, hctx, false); + /* + * Don't clear RESTART here, someone else could have set it. + * At most this will cost an extra queue run. + */ } else { wait = &this_hctx->dispatch_wait; if (!list_empty_careful(&wait->entry)) @@ -1052,37 +1057,21 @@ static bool blk_mq_mark_tag_wait(struct blk_mq_hw_ctx **hctx, ws = bt_wait_ptr(&this_hctx->tags->bitmap_tags, this_hctx); add_wait_queue(&ws->wait, wait); - } - - /* - * It's possible that a tag was freed in the window between the - * allocation failure and adding the hardware queue to the wait - * queue. - */ - ret = blk_mq_get_driver_tag(rq, hctx, false); - - if (!shared_tags) { /* - * Don't clear RESTART here, someone else could have set it. - * At most this will cost an extra queue run. + * It's possible that a tag was freed in the window between the + * allocation failure and adding the hardware queue to the wait + * queue. */ - return ret; - } else { - if (!ret) { - spin_unlock(&this_hctx->lock); - return false; + ret = blk_mq_get_driver_tag(rq, hctx, false); + /* If we got a tag remove ourselves from the wait queue. */ + if (ret) { + spin_lock_irq(&ws->wait.lock); + list_del_init(&wait->entry); + spin_unlock_irq(&ws->wait.lock); } - - /* - * We got a tag, remove ourselves from the wait queue to ensure - * someone else gets the wakeup. - */ - spin_lock_irq(&ws->wait.lock); - list_del_init(&wait->entry); - spin_unlock_irq(&ws->wait.lock); spin_unlock(&this_hctx->lock); - return true; } + return ret; } bool blk_mq_dispatch_rq_list(struct request_queue *q, struct list_head *list, -- 2.15.0
