From e0097cf5f2f1b7b8a594beaa32a604776d3ca6ce Mon Sep 17 00:00:00 2001 From: Adrian Hunter Date: Tue, 29 Nov 2016 12:09:10 +0200 Subject: mmc: queue: Fix queue thread wake-up The only time the driver sleeps expecting to be woken upon the arrival of a new request, is when the dispatch queue is empty. The only time that it is known whether the dispatch queue is empty is after NULL is returned from blk_fetch_request() while under the queue lock. Recognizing those facts, simplify the synchronization between the queue thread and the request function. A couple of flags tell the request function what to do, and the queue lock and barriers associated with wake-ups ensure synchronization. The result is simpler and allows the removal of the context_info lock. Signed-off-by: Adrian Hunter Reviewed-by: Linus Walleij Reviewed-by: Harjani Ritesh Signed-off-by: Ulf Hansson --- drivers/mmc/card/queue.c | 35 +++++++++++++++++++++-------------- 1 file changed, 21 insertions(+), 14 deletions(-) (limited to 'drivers/mmc/card/queue.c') diff --git a/drivers/mmc/card/queue.c b/drivers/mmc/card/queue.c index 7dacf2744fbd..010888d8d97c 100644 --- a/drivers/mmc/card/queue.c +++ b/drivers/mmc/card/queue.c @@ -53,6 +53,7 @@ static int mmc_queue_thread(void *d) { struct mmc_queue *mq = d; struct request_queue *q = mq->queue; + struct mmc_context_info *cntx = &mq->card->host->context_info; current->flags |= PF_MEMALLOC; @@ -63,6 +64,19 @@ static int mmc_queue_thread(void *d) spin_lock_irq(q->queue_lock); set_current_state(TASK_INTERRUPTIBLE); req = blk_fetch_request(q); + mq->asleep = false; + cntx->is_waiting_last_req = false; + cntx->is_new_req = false; + if (!req) { + /* + * Dispatch queue is empty so set flags for + * mmc_request_fn() to wake us up. + */ + if (mq->mqrq_prev->req) + cntx->is_waiting_last_req = true; + else + mq->asleep = true; + } mq->mqrq_cur->req = req; spin_unlock_irq(q->queue_lock); @@ -115,7 +129,6 @@ static void mmc_request_fn(struct request_queue *q) { struct mmc_queue *mq = q->queuedata; struct request *req; - unsigned long flags; struct mmc_context_info *cntx; if (!mq) { @@ -127,19 +140,13 @@ static void mmc_request_fn(struct request_queue *q) } cntx = &mq->card->host->context_info; - if (!mq->mqrq_cur->req && mq->mqrq_prev->req) { - /* - * New MMC request arrived when MMC thread may be - * blocked on the previous request to be complete - * with no current request fetched - */ - spin_lock_irqsave(&cntx->lock, flags); - if (cntx->is_waiting_last_req) { - cntx->is_new_req = true; - wake_up_interruptible(&cntx->wait); - } - spin_unlock_irqrestore(&cntx->lock, flags); - } else if (!mq->mqrq_cur->req && !mq->mqrq_prev->req) + + if (cntx->is_waiting_last_req) { + cntx->is_new_req = true; + wake_up_interruptible(&cntx->wait); + } + + if (mq->asleep) wake_up_process(mq->thread); } -- cgit v1.2.3-59-g8ed1b