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SubjectRe: [PATCH V13 07/10] mmc: block: blk-mq: Add support for direct completion
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On 09/11/17 15:07, Ulf Hansson wrote:
> On 3 November 2017 at 14:20, Adrian Hunter <adrian.hunter@intel.com> wrote:
>> For blk-mq, add support for completing requests directly in the ->done
>> callback. That means that error handling and urgent background operations
>> must be handled by recovery_work in that case.
>
> As the mmc docs sucks, I think it's important that we elaborate a bit
> more on the constraints this has on the host driver, here in the
> changelog.
>
> Something along the lines, "Using MMC_CAP_DIRECT_COMPLETE requires the
> host driver, when calling mmc_request_done(), to cope with that its
> ->post_req() callback may be called immediately from the same context,
> etc.."

Yes, I will expand it. It is also a stepping stone to getting to support
for issuing the next request from the ->done() callback.

>
> Otherwise this looks good to me.
>
> Kind regards
> Uffe
>
>>
>> Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
>> ---
>> drivers/mmc/core/block.c | 100 +++++++++++++++++++++++++++++++++++++++++------
>> drivers/mmc/core/block.h | 1 +
>> drivers/mmc/core/queue.c | 5 ++-
>> drivers/mmc/core/queue.h | 6 +++
>> include/linux/mmc/host.h | 1 +
>> 5 files changed, 101 insertions(+), 12 deletions(-)
>>
>> diff --git a/drivers/mmc/core/block.c b/drivers/mmc/core/block.c
>> index e8be17152884..cbb4b35a592d 100644
>> --- a/drivers/mmc/core/block.c
>> +++ b/drivers/mmc/core/block.c
>> @@ -2086,6 +2086,22 @@ static void mmc_blk_rw_recovery(struct mmc_queue *mq, struct request *req)
>> }
>> }
>>
>> +static inline bool mmc_blk_rq_error(struct mmc_blk_request *brq)
>> +{
>> + mmc_blk_eval_resp_error(brq);
>> +
>> + return brq->sbc.error || brq->cmd.error || brq->stop.error ||
>> + brq->data.error || brq->cmd.resp[0] & CMD_ERRORS;
>> +}
>> +
>> +static inline void mmc_blk_rw_reset_success(struct mmc_queue *mq,
>> + struct request *req)
>> +{
>> + int type = rq_data_dir(req) == READ ? MMC_BLK_READ : MMC_BLK_WRITE;
>> +
>> + mmc_blk_reset_success(mq->blkdata, type);
>> +}
>> +
>> static void mmc_blk_mq_complete_rq(struct mmc_queue *mq, struct request *req)
>> {
>> struct mmc_queue_req *mqrq = req_to_mmc_queue_req(req);
>> @@ -2167,14 +2183,43 @@ static void mmc_blk_mq_post_req(struct mmc_queue *mq, struct request *req)
>> if (host->ops->post_req)
>> host->ops->post_req(host, mrq, 0);
>>
>> - blk_mq_complete_request(req);
>> + /*
>> + * Block layer timeouts race with completions which means the normal
>> + * completion path cannot be used during recovery.
>> + */
>> + if (mq->in_recovery)
>> + mmc_blk_mq_complete_rq(mq, req);
>> + else
>> + blk_mq_complete_request(req);
>>
>> mmc_blk_mq_acct_req_done(mq, req);
>> }
>>
>> +void mmc_blk_mq_recovery(struct mmc_queue *mq)
>> +{
>> + struct request *req = mq->recovery_req;
>> + struct mmc_host *host = mq->card->host;
>> + struct mmc_queue_req *mqrq = req_to_mmc_queue_req(req);
>> +
>> + mq->recovery_req = NULL;
>> + mq->rw_wait = false;
>> +
>> + if (mmc_blk_rq_error(&mqrq->brq)) {
>> + mmc_retune_hold_now(host);
>> + mmc_blk_rw_recovery(mq, req);
>> + }
>> +
>> + mmc_blk_urgent_bkops(mq, mqrq);
>> +
>> + mmc_blk_mq_post_req(mq, req);
>> +}
>> +
>> static void mmc_blk_mq_complete_prev_req(struct mmc_queue *mq,
>> struct request **prev_req)
>> {
>> + if (mmc_queue_direct_complete(mq->card->host))
>> + return;
>> +
>> mutex_lock(&mq->complete_lock);
>>
>> if (!mq->complete_req)
>> @@ -2208,19 +2253,43 @@ static void mmc_blk_mq_req_done(struct mmc_request *mrq)
>> struct request *req = mmc_queue_req_to_req(mqrq);
>> struct request_queue *q = req->q;
>> struct mmc_queue *mq = q->queuedata;
>> + struct mmc_host *host = mq->card->host;
>> unsigned long flags;
>> - bool waiting;
>>
>> - spin_lock_irqsave(q->queue_lock, flags);
>> - mq->complete_req = req;
>> - mq->rw_wait = false;
>> - waiting = mq->waiting;
>> - spin_unlock_irqrestore(q->queue_lock, flags);
>> + if (!mmc_queue_direct_complete(host)) {
>> + bool waiting;
>> +
>> + spin_lock_irqsave(q->queue_lock, flags);
>> + mq->complete_req = req;
>> + mq->rw_wait = false;
>> + waiting = mq->waiting;
>> + spin_unlock_irqrestore(q->queue_lock, flags);
>> +
>> + if (waiting)
>> + wake_up(&mq->wait);
>> + else
>> + kblockd_schedule_work(&mq->complete_work);
>>
>> - if (waiting)
>> + return;
>> + }
>> +
>> + if (mmc_blk_rq_error(&mqrq->brq) ||
>> + mmc_blk_urgent_bkops_needed(mq, mqrq)) {
>> + spin_lock_irqsave(q->queue_lock, flags);
>> + mq->recovery_needed = true;
>> + mq->recovery_req = req;
>> + spin_unlock_irqrestore(q->queue_lock, flags);
>> wake_up(&mq->wait);
>> - else
>> - kblockd_schedule_work(&mq->complete_work);
>> + schedule_work(&mq->recovery_work);
>> + return;
>> + }
>> +
>> + mmc_blk_rw_reset_success(mq, req);
>> +
>> + mq->rw_wait = false;
>> + wake_up(&mq->wait);
>> +
>> + mmc_blk_mq_post_req(mq, req);
>> }
>>
>> static bool mmc_blk_rw_wait_cond(struct mmc_queue *mq, int *err)
>> @@ -2230,7 +2299,12 @@ static bool mmc_blk_rw_wait_cond(struct mmc_queue *mq, int *err)
>> bool done;
>>
>> spin_lock_irqsave(q->queue_lock, flags);
>> - done = !mq->rw_wait;
>> + if (mq->recovery_needed) {
>> + *err = -EBUSY;
>> + done = true;
>> + } else {
>> + done = !mq->rw_wait;
>> + }
>> mq->waiting = !done;
>> spin_unlock_irqrestore(q->queue_lock, flags);
>>
>> @@ -2277,6 +2351,10 @@ static int mmc_blk_mq_issue_rw_rq(struct mmc_queue *mq,
>> if (err)
>> mq->rw_wait = false;
>>
>> + /* Release re-tuning here where there is no synchronization required */
>> + if (mmc_queue_direct_complete(host))
>> + mmc_retune_release(host);
>> +
>> out_post_req:
>> if (err && host->ops->post_req)
>> host->ops->post_req(host, &mqrq->brq.mrq, err);
>> diff --git a/drivers/mmc/core/block.h b/drivers/mmc/core/block.h
>> index 6c0e98c1af71..5ad22c1c0318 100644
>> --- a/drivers/mmc/core/block.h
>> +++ b/drivers/mmc/core/block.h
>> @@ -12,6 +12,7 @@
>>
>> enum mmc_issued mmc_blk_mq_issue_rq(struct mmc_queue *mq, struct request *req);
>> void mmc_blk_mq_complete(struct request *req);
>> +void mmc_blk_mq_recovery(struct mmc_queue *mq);
>>
>> struct work_struct;
>>
>> diff --git a/drivers/mmc/core/queue.c b/drivers/mmc/core/queue.c
>> index 971f97698866..bcba2995c767 100644
>> --- a/drivers/mmc/core/queue.c
>> +++ b/drivers/mmc/core/queue.c
>> @@ -165,7 +165,10 @@ static void mmc_mq_recovery_handler(struct work_struct *work)
>>
>> mq->in_recovery = true;
>>
>> - mmc_blk_cqe_recovery(mq);
>> + if (mq->use_cqe)
>> + mmc_blk_cqe_recovery(mq);
>> + else
>> + mmc_blk_mq_recovery(mq);
>>
>> mq->in_recovery = false;
>>
>> diff --git a/drivers/mmc/core/queue.h b/drivers/mmc/core/queue.h
>> index f05b5a9d2f87..9bbfbb1fad7b 100644
>> --- a/drivers/mmc/core/queue.h
>> +++ b/drivers/mmc/core/queue.h
>> @@ -102,6 +102,7 @@ struct mmc_queue {
>> bool waiting;
>> struct work_struct recovery_work;
>> wait_queue_head_t wait;
>> + struct request *recovery_req;
>> struct request *complete_req;
>> struct mutex complete_lock;
>> struct work_struct complete_work;
>> @@ -133,4 +134,9 @@ static inline int mmc_cqe_qcnt(struct mmc_queue *mq)
>> mq->in_flight[MMC_ISSUE_ASYNC];
>> }
>>
>> +static inline bool mmc_queue_direct_complete(struct mmc_host *host)
>> +{
>> + return host->caps & MMC_CAP_DIRECT_COMPLETE;
>> +}
>> +
>> #endif
>> diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
>> index ce2075d6f429..4b68a95a8818 100644
>> --- a/include/linux/mmc/host.h
>> +++ b/include/linux/mmc/host.h
>> @@ -324,6 +324,7 @@ struct mmc_host {
>> #define MMC_CAP_DRIVER_TYPE_A (1 << 23) /* Host supports Driver Type A */
>> #define MMC_CAP_DRIVER_TYPE_C (1 << 24) /* Host supports Driver Type C */
>> #define MMC_CAP_DRIVER_TYPE_D (1 << 25) /* Host supports Driver Type D */
>> +#define MMC_CAP_DIRECT_COMPLETE (1 << 27) /* RW reqs can be completed within mmc_request_done() */
>> #define MMC_CAP_CD_WAKE (1 << 28) /* Enable card detect wake */
>> #define MMC_CAP_CMD_DURING_TFR (1 << 29) /* Commands during data transfer */
>> #define MMC_CAP_CMD23 (1 << 30) /* CMD23 supported. */
>> --
>> 1.9.1
>>
>

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