On 19/10/2021 14:32, Ulf Hansson wrote:
> + Adrian
>
> On Mon, 18 Oct 2021 at 15:56, Sebastian Andrzej Siewior
> <bigeasy@xxxxxxxxxxxxx> wrote:
>>
>> The completion callback for the sdhci-pci device is invoked from a
>> kworker.
>> I couldn't identify in which context is mmc_blk_mq_req_done() invoke but
>> the remaining caller are from invoked from preemptible context. Here it
>> would make sense to complete the request directly instead scheduling
>> ksoftirqd for its completion.
>>
>> Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
>
> Thanks for working on this!
>
> I have looped in Adrian, to allow him to provide us with his input too.
Thanks!
Looks good to me.
Acked-by: Adrian Hunter <adrian.hunter@xxxxxxxxx>
>
>> ---
>> drivers/mmc/core/block.c | 22 ++++++++++++++--------
>> 1 file changed, 14 insertions(+), 8 deletions(-)
>>
>> diff --git a/drivers/mmc/core/block.c b/drivers/mmc/core/block.c
>> index 431af5e8be2f8..7d6b43fe52e8a 100644
>> --- a/drivers/mmc/core/block.c
>> +++ b/drivers/mmc/core/block.c
>> @@ -2051,7 +2051,8 @@ static void mmc_blk_mq_dec_in_flight(struct mmc_queue *mq, struct request *req)
>> mmc_put_card(mq->card, &mq->ctx);
>> }
>>
>> -static void mmc_blk_mq_post_req(struct mmc_queue *mq, struct request *req)
>> +static void mmc_blk_mq_post_req(struct mmc_queue *mq, struct request *req,
>> + bool can_sleep)
>> {
>> struct mmc_queue_req *mqrq = req_to_mmc_queue_req(req);
>> struct mmc_request *mrq = &mqrq->brq.mrq;
>> @@ -2063,10 +2064,14 @@ static void mmc_blk_mq_post_req(struct mmc_queue *mq, struct request *req)
>> * Block layer timeouts race with completions which means the normal
>> * completion path cannot be used during recovery.
>> */
>> - if (mq->in_recovery)
>> + if (mq->in_recovery) {
>> mmc_blk_mq_complete_rq(mq, req);
>> - else if (likely(!blk_should_fake_timeout(req->q)))
>> - blk_mq_complete_request(req);
>> + } else if (likely(!blk_should_fake_timeout(req->q))) {
>> + if (can_sleep)
>> + blk_mq_complete_request_direct(req, mmc_blk_mq_complete);
>> + else
>> + blk_mq_complete_request(req);
>> + }
>>
>> mmc_blk_mq_dec_in_flight(mq, req);
>> }
>> @@ -2087,7 +2092,7 @@ void mmc_blk_mq_recovery(struct mmc_queue *mq)
>>
>> mmc_blk_urgent_bkops(mq, mqrq);
>>
>> - mmc_blk_mq_post_req(mq, req);
>> + mmc_blk_mq_post_req(mq, req, true);
>> }
>>
>> static void mmc_blk_mq_complete_prev_req(struct mmc_queue *mq,
>> @@ -2106,7 +2111,7 @@ static void mmc_blk_mq_complete_prev_req(struct mmc_queue *mq,
>> if (prev_req)
>> *prev_req = mq->complete_req;
>> else
>> - mmc_blk_mq_post_req(mq, mq->complete_req);
>> + mmc_blk_mq_post_req(mq, mq->complete_req, true);
>>
>> mq->complete_req = NULL;
>>
>> @@ -2178,7 +2183,8 @@ static void mmc_blk_mq_req_done(struct mmc_request *mrq)
>> mq->rw_wait = false;
>> wake_up(&mq->wait);
>>
>> - mmc_blk_mq_post_req(mq, req);
>> + /* context unknown */
>> + mmc_blk_mq_post_req(mq, req, false);
>
> So it seems we would benefit from knowing the context here, right?
>
> At this point, what you suggest seems like a reasonable way forward
> (assuming atomic context), but in a next step we could potentially add
> a non-atomic helper function for mmc host drivers to call, when that
> is suitable. Would that make sense you think?
>
>> }
>>
>> static bool mmc_blk_rw_wait_cond(struct mmc_queue *mq, int *err)
>> @@ -2238,7 +2244,7 @@ static int mmc_blk_mq_issue_rw_rq(struct mmc_queue *mq,
>> err = mmc_start_request(host, &mqrq->brq.mrq);
>>
>> if (prev_req)
>> - mmc_blk_mq_post_req(mq, prev_req);
>> + mmc_blk_mq_post_req(mq, prev_req, true);
>>
>> if (err)
>> mq->rw_wait = false;
>
> Kind regards
> Uffe
>
