Re: [PATCH V3] mmc:core: Avoid useless detecting task when card is busy

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Hi Haijun,


On 24 September 2013 05:42, Zhang Haijun <b42677@xxxxxxxxxxxxx> wrote:
> Hi, Ulf
>
> I had update the patch according to your suggestion.
> I test on my platform during last night.
> About 200G random continuous data was written to 32G SDHC Card.
> No call trace was encountered.
> I think it can meet with your demand and solve the problem.

Sounds promising. :-)

>
>
> 于 2013/9/24 10:08, Haijun Zhang 写道:
>> When card is in cpu polling mode to detect card present. Card detecting
>> task will be scheduled about once every second. When card is busy in large
>> file transfer, detecting task will be hang and call trace will be prompt.
>> When handling the request, CMD13 is always followed by every command when
>> it was complete. So assume that card is present to avoid this duplicate
>> detecting. Only polling card when card is free to reduce conflict with
>> data transfer.
>>
>> <7>mmc0: req done (CMD13): 0: 00000e00 00000000 00000000 00000000
>> INFO: task kworker/u:1:12 blocked for more than 120 seconds.
>> "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
>> kworker/u:1     D 00000000     0    12      2 0x00000000
>> Call Trace:
>> [ee06dd50] [44042028] 0x44042028
>> (unreliable)
>> [ee06de10] [c0007a0c] __switch_to+0xa0/0xf0
>> [ee06de30] [c04dd50c] __schedule+0x1f8/0x4a4
>>
>> [ee06dea0] [c04dd898] schedule+0x30/0xbc
>>
>> [ee06deb0] [c03816a4] __mmc_claim_host+0x98/0x19c
>>
>> [ee06df00] [c0385f88] mmc_sd_detect+0x38/0xc0
>>
>> [ee06df10] [c0382b0c] mmc_rescan+0x294/0x2e0
>> [ee06df40] [c00661cc] process_one_work+0x140/0x3e0
>>
>> [ee06df70] [c0066bf8] worker_thread+0x18c/0x36c
>> [ee06dfb0] [c006bf10] kthread+0x7c/0x80
>>
>> [ee06dff0] [c000de58] kernel_thread+0x4c/0x68
>> <7>sdhci [sdhci_irq()]: *** mmc0 got interrupt: 0x00000001
>>
>> Signed-off-by: Haijun Zhang <haijun.zhang@xxxxxxxxxxxxx>
>> ---
>> changes for V3:
>>       - Remove mmc_try_claim_host.
>> changes for V2:
>>       - Add card detecting once the last request is done.
>>
>>  drivers/mmc/card/block.c | 29 +++++++++++++++++++++++++++--
>>  drivers/mmc/core/mmc.c   |  5 +++++
>>  drivers/mmc/core/sd.c    |  5 +++++
>>  drivers/mmc/core/sdio.c  |  5 +++++
>>  4 files changed, 42 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c
>> index 1a3163f..d1f1730 100644
>> --- a/drivers/mmc/card/block.c
>> +++ b/drivers/mmc/card/block.c
>> @@ -1960,9 +1960,21 @@ static int mmc_blk_issue_rq(struct mmc_queue *mq, struct request *req)
>>       struct mmc_host *host = card->host;
>>       unsigned long flags;
>>
>> -     if (req && !mq->mqrq_prev->req)
>> +     if (req && !mq->mqrq_prev->req) {
>> +             /*
>> +              * When we are here, card polling task will be blocked.
>> +              * So disable it to avoid this useless schedule.
>> +              */
>> +             if (host->caps & MMC_CAP_NEEDS_POLL) {
>> +                     spin_lock_irqsave(&host->lock, flags);
>> +                     host->rescan_disable = 1;
>> +                     spin_unlock_irqrestore(&host->lock, flags);
>> +                     cancel_delayed_work(&host->detect);
>> +             }
>> +
>>               /* claim host only for the first request */
>>               mmc_get_card(card);
>> +     }
>>
>>       ret = mmc_blk_part_switch(card, md);
>>       if (ret) {
>> @@ -1999,7 +2011,7 @@ static int mmc_blk_issue_rq(struct mmc_queue *mq, struct request *req)
>>
>>  out:
>>       if ((!req && !(mq->flags & MMC_QUEUE_NEW_REQUEST)) ||
>> -          (req && (req->cmd_flags & MMC_REQ_SPECIAL_MASK)))
>> +                     (req && (req->cmd_flags & MMC_REQ_SPECIAL_MASK))) {
>>               /*
>>                * Release host when there are no more requests
>>                * and after special request(discard, flush) is done.
>> @@ -2007,6 +2019,19 @@ out:
>>                * the 'mmc_blk_issue_rq' with 'mqrq_prev->req'.
>>                */
>>               mmc_put_card(card);
>> +
>> +             /*
>> +              * Detecting card status immediately in case card being
>> +              * removed just after the request is complete.
>> +              */
>> +             if (host->caps & MMC_CAP_NEEDS_POLL) {
>> +                     spin_lock_irqsave(&host->lock, flags);
>> +                     host->rescan_disable = 0;
>> +                     spin_unlock_irqrestore(&host->lock, flags);
>> +                     mmc_detect_change(host, 0);
>> +             }
>> +     }
>> +
>>       return ret;
>>  }
>>
>> diff --git a/drivers/mmc/core/mmc.c b/drivers/mmc/core/mmc.c
>> index 6d02012..4bdf68c 100644
>> --- a/drivers/mmc/core/mmc.c
>> +++ b/drivers/mmc/core/mmc.c
>> @@ -1443,6 +1443,7 @@ static int mmc_alive(struct mmc_host *host)
>>  static void mmc_detect(struct mmc_host *host)
>>  {
>>       int err;
>> +     unsigned long flags;
>>
>>       BUG_ON(!host);
>>       BUG_ON(!host->card);
>> @@ -1457,6 +1458,10 @@ static void mmc_detect(struct mmc_host *host)
>>       mmc_put_card(host->card);
>>
>>       if (err) {
>> +             spin_lock_irqsave(&host->lock, flags);
>> +             host->rescan_disable = 0;
>> +             spin_unlock_irqrestore(&host->lock, flags);
>> +
>>               mmc_remove(host);
>>
>>               mmc_claim_host(host);
>> diff --git a/drivers/mmc/core/sd.c b/drivers/mmc/core/sd.c
>> index 5e8823d..c87203c 100644
>> --- a/drivers/mmc/core/sd.c
>> +++ b/drivers/mmc/core/sd.c
>> @@ -1041,6 +1041,7 @@ static int mmc_sd_alive(struct mmc_host *host)
>>  static void mmc_sd_detect(struct mmc_host *host)
>>  {
>>       int err;
>> +     unsigned long flags;
>>
>>       BUG_ON(!host);
>>       BUG_ON(!host->card);
>> @@ -1055,6 +1056,10 @@ static void mmc_sd_detect(struct mmc_host *host)
>>       mmc_put_card(host->card);
>>
>>       if (err) {
>> +             spin_lock_irqsave(&host->lock, flags);
>> +             host->rescan_disable = 0;
>> +             spin_unlock_irqrestore(&host->lock, flags);
>> +
>>               mmc_sd_remove(host);
>>
>>               mmc_claim_host(host);
>> diff --git a/drivers/mmc/core/sdio.c b/drivers/mmc/core/sdio.c
>> index 80d89cff..a59e34b 100644
>> --- a/drivers/mmc/core/sdio.c
>> +++ b/drivers/mmc/core/sdio.c
>> @@ -862,6 +862,7 @@ static int mmc_sdio_alive(struct mmc_host *host)
>>  static void mmc_sdio_detect(struct mmc_host *host)
>>  {
>>       int err;
>> +     unsigned long flags;
>>
>>       BUG_ON(!host);
>>       BUG_ON(!host->card);
>> @@ -900,6 +901,10 @@ static void mmc_sdio_detect(struct mmc_host *host)
>>
>>  out:
>>       if (err) {
>> +             spin_lock_irqsave(&host->lock, flags);
>> +             host->rescan_disable = 0;
>> +             spin_unlock_irqrestore(&host->lock, flags);
>> +
>>               mmc_sdio_remove(host);
>>
>>               mmc_claim_host(host);
>

Re-enabling the rescan, like "host->rescan_disable = 0" shall be done
from mmc_detect_card_removed function instead of from mmc_detect,
mmc_sd_detect mmc_sdio_detect.

Look into the mmc_detect_card_removed and where specific error
handling is done for MMC_CAP_NEEDS_POLL.

Kind regards
Ulf Hansson

> --
> Thanks & Regards
> Haijun.
>
>
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