Re: [PATCH 12/16] mmc: queue: stop flushing the pipeline with NULL

Bartlomiej Zolnierkiewicz
2017-02-28T18:03:06Z

On Thursday, February 09, 2017 04:33:59 PM Linus Walleij wrote:
> Remove all the pipeline flush: i.e. repeatedly sending NULL
> down to the core layer to flush out asynchronous requests,
> and also sending NULL after "special" commands to achieve the
> same flush.
>
> Instead: let the "special" commands wait for any ongoing
> asynchronous transfers using the completion, and apart from
> that expect the core.c and block.c layers to deal with the
> ongoing requests autonomously without any "push" from the
> queue.
>
> Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
> ---
> drivers/mmc/core/block.c | 80 +++++++++++++++++-------------------------------
> drivers/mmc/core/core.c | 37 ++++++++++------------
> drivers/mmc/core/queue.c | 18 ++++++++---
> include/linux/mmc/core.h | 5 ++-
> 4 files changed, 60 insertions(+), 80 deletions(-)
>
> diff --git a/drivers/mmc/core/block.c b/drivers/mmc/core/block.c
> index 0bd9070f5f2e..4952a105780e 100644
> --- a/drivers/mmc/core/block.c
> +++ b/drivers/mmc/core/block.c
> @@ -1753,42 +1753,27 @@ void mmc_blk_rw_done(struct mmc_async_req *areq,
>
> static void mmc_blk_issue_rw_rq(struct mmc_queue *mq, struct request *new_req)
> {
> - enum mmc_blk_status status;
> - struct mmc_async_req *new_areq;
> - struct mmc_async_req *old_areq;
> struct mmc_card *card = mq->card;
>
> - if (!new_req && !mq->mqrq_prev->req)
> + if (!new_req) {
> + pr_err("%s: NULL request!\n", __func__);
> return;
> + }
>
> - if (new_req) {
> - /*
> - * When 4KB native sector is enabled, only 8 blocks
> - * multiple read or write is allowed
> - */
> - if (mmc_large_sector(card) &&
> - !IS_ALIGNED(blk_rq_sectors(new_req), 8)) {
> - pr_err("%s: Transfer size is not 4KB sector size aligned\n",
> - new_req->rq_disk->disk_name);
> - mmc_blk_rw_cmd_abort(card, new_req);
> - return;
> - }
> -
> - mmc_blk_rw_rq_prep(mq->mqrq_cur, card, 0, mq);
> - new_areq = &mq->mqrq_cur->areq;
> - } else
> - new_areq = NULL;
> -
> - old_areq = mmc_start_areq(card->host, new_areq, &status);
> - if (!old_areq) {
> - /*
> - * We have just put the first request into the pipeline
> - * and there is nothing more to do until it is
> - * complete.
> - */
> + /*
> + * When 4KB native sector is enabled, only 8 blocks
> + * multiple read or write is allowed
> + */
> + if (mmc_large_sector(card) &&
> + !IS_ALIGNED(blk_rq_sectors(new_req), 8)) {
> + pr_err("%s: Transfer size is not 4KB sector size aligned\n",
> + new_req->rq_disk->disk_name);
> + mmc_blk_rw_cmd_abort(card, new_req);
> return;
> }
> - /* FIXME: yes, we just disregard the old_areq */
> +
> + mmc_blk_rw_rq_prep(mq->mqrq_cur, card, 0, mq);
> + mmc_start_areq(card->host, &mq->mqrq_cur->areq);
> }
>
> void mmc_blk_issue_rq(struct mmc_queue *mq, struct request *req)
> @@ -1796,48 +1781,39 @@ void mmc_blk_issue_rq(struct mmc_queue *mq, struct request *req)
> int ret;
> struct mmc_blk_data *md = mq->blkdata;
> struct mmc_card *card = md->queue.card;
> - bool req_is_special = mmc_req_is_special(req);
> -
> - if (req && !mq->mqrq_prev->req)
> - /* claim host only for the first request */
> - mmc_get_card(card);
>
> ret = mmc_blk_part_switch(card, md);
> if (ret) {
> if (req) {
> blk_end_request_all(req, -EIO);
> }
> - goto out;
> + return;
> }
>
> if (req && req_op(req) == REQ_OP_DISCARD) {
> /* complete ongoing async transfer before issuing discard */
> - if (card->host->areq)
> - mmc_blk_issue_rw_rq(mq, NULL);
> + if (card->host->areq) {
> + wait_for_completion(&card->host->areq->complete);
> + card->host->areq = NULL;
> + }
> mmc_blk_issue_discard_rq(mq, req);
> } else if (req && req_op(req) == REQ_OP_SECURE_ERASE) {
> /* complete ongoing async transfer before issuing secure erase*/
> - if (card->host->areq)
> - mmc_blk_issue_rw_rq(mq, NULL);
> + if (card->host->areq) {
> + wait_for_completion(&card->host->areq->complete);
> + card->host->areq = NULL;
> + }
> mmc_blk_issue_secdiscard_rq(mq, req);
> } else if (req && req_op(req) == REQ_OP_FLUSH) {
> /* complete ongoing async transfer before issuing flush */
> - if (card->host->areq)
> - mmc_blk_issue_rw_rq(mq, NULL);
> + if (card->host->areq) {
> + wait_for_completion(&card->host->areq->complete);
> + card->host->areq = NULL;
> + }
> mmc_blk_issue_flush(mq, req);
> } else {
> mmc_blk_issue_rw_rq(mq, req);
> }
> -
> -out:
> - if (!req || req_is_special)
> - /*
> - * Release host when there are no more requests
> - * and after special request(discard, flush) is done.
> - * In case sepecial request, there is no reentry to
> - * the 'mmc_blk_issue_rq' with 'mqrq_prev->req'.
> - */
> - mmc_put_card(card);
> }
>
> static inline int mmc_blk_readonly(struct mmc_card *card)
> diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
> index 34337ef6705e..03c290e5e2c9 100644
> --- a/drivers/mmc/core/core.c
> +++ b/drivers/mmc/core/core.c
> @@ -667,42 +667,37 @@ EXPORT_SYMBOL(mmc_restart_areq);
> * return the completed request. If there is no ongoing request, NULL
> * is returned without waiting. NULL is not an error condition.
> */
> -struct mmc_async_req *mmc_start_areq(struct mmc_host *host,
> - struct mmc_async_req *areq,
> - enum mmc_blk_status *ret_stat)
> +int mmc_start_areq(struct mmc_host *host,
> + struct mmc_async_req *areq)
> {
> - enum mmc_blk_status status;
> - int start_err = 0;
> + int ret;
> struct mmc_async_req *previous = host->areq;
>
> /* Prepare a new request */
> - if (areq)
> - mmc_pre_req(host, areq->mrq);
> + if (!areq) {
> + pr_err("%s: NULL asynchronous request!\n", __func__);
> + return -EIO;
> + }
> +
> + mmc_pre_req(host, areq->mrq);
>
> /* Finalize previous request, if there is one */
> if (previous)
> wait_for_completion(&previous->complete);
>
> - status = MMC_BLK_SUCCESS;
> - if (ret_stat)
> - *ret_stat = status;
> -
> /* Fine so far, start the new request! */
> - if (status == MMC_BLK_SUCCESS && areq) {
> - init_completion(&areq->complete);
> - start_err = __mmc_start_data_req(host, areq->mrq);
> - }
> + init_completion(&areq->complete);
> + ret = __mmc_start_data_req(host, areq->mrq);
>
> /* Cancel a prepared request if it was not started. */
> - if ((status != MMC_BLK_SUCCESS || start_err) && areq)
> + if (ret) {
> mmc_post_req(host, areq->mrq, -EINVAL);
> -
> - if (status != MMC_BLK_SUCCESS)
> host->areq = NULL;
> - else
> - host->areq = areq;
> + pr_err("%s: failed to start request\n", __func__);
> + }
> + host->areq = areq;
>
> - return previous;
> + return ret;
> }
> EXPORT_SYMBOL(mmc_start_areq);
>
> diff --git a/drivers/mmc/core/queue.c b/drivers/mmc/core/queue.c
> index ae6837317fe0..c9f28de7b0f4 100644
> --- a/drivers/mmc/core/queue.c
> +++ b/drivers/mmc/core/queue.c
> @@ -53,6 +53,7 @@ static int mmc_queue_thread(void *d)
> {
> struct mmc_queue *mq = d;
> struct request_queue *q = mq->queue;
> + bool claimed_host = false;
>
> current->flags |= PF_MEMALLOC;
>
> @@ -67,9 +68,11 @@ static int mmc_queue_thread(void *d)
> mq->mqrq_cur->req = req;
> spin_unlock_irq(q->queue_lock);
>
> - if (req || mq->mqrq_prev->req) {
> + if (req) {
> bool req_is_special = mmc_req_is_special(req);
>
> + if (!claimed_host)
> + mmc_get_card(mq->card);

missing
claimed_host = true;

?

> set_current_state(TASK_RUNNING);
> mmc_blk_issue_rq(mq, req);
> cond_resched();
> @@ -78,11 +81,14 @@ static int mmc_queue_thread(void *d)
> * and vice versa.
> * In case of special requests, current request
> * has been finished. Do not assign it to previous
> - * request.
> + * request. Always unclaim the host after special
> + * commands.
> */
> - if (req_is_special)
> + if (req_is_special) {
> mq->mqrq_cur->req = NULL;
> -
> + mmc_put_card(mq->card);
> + claimed_host = false;
> + }
> mq->mqrq_prev->brq.mrq.data = NULL;
> mq->mqrq_prev->req = NULL;
> swap(mq->mqrq_prev, mq->mqrq_cur);
> @@ -97,6 +103,10 @@ static int mmc_queue_thread(void *d)
> down(&mq->thread_sem);
> }
> } while (1);
> +
> + if (claimed_host)

claimed_host is never set to true

> + mmc_put_card(mq->card);
> +
> up(&mq->thread_sem);
>
> return 0;
> diff --git a/include/linux/mmc/core.h b/include/linux/mmc/core.h
> index 55b45dcddee6..af651e723ba2 100644
> --- a/include/linux/mmc/core.h
> +++ b/include/linux/mmc/core.h
> @@ -160,9 +160,8 @@ struct mmc_async_req;
>
> void mmc_finalize_areq(struct kthread_work *work);
> int mmc_restart_areq(struct mmc_host *host, struct mmc_async_req *areq);
> -struct mmc_async_req *mmc_start_areq(struct mmc_host *host,
> - struct mmc_async_req *areq,
> - enum mmc_blk_status *ret_stat);
> +int mmc_start_areq(struct mmc_host *host,
> + struct mmc_async_req *areq);
> void mmc_wait_for_req(struct mmc_host *host, struct mmc_request *mrq);
> int mmc_wait_for_cmd(struct mmc_host *host, struct mmc_command *cmd,
> int retries);

Best regards,
--
Bartlomiej Zolnierkiewicz
Samsung R&D Institute Poland
Samsung Electronics