Re: [PATCH V5] mmc:core: Avoid useless detecting task when card is busy

[Zhang Haijun <b42677@freescale.com>]

Hi, chris

The patch is acked by Ulf.

Could you give some advice?

Thanks.

于 2013/9/26 10:56, 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@freescale.com>
> Acked-by: Ulf Hansson <ulf.hansson@linaro.org>
> ---
>  drivers/mmc/card/block.c | 28 ++++++++++++++++++++++++++--
>  drivers/mmc/core/core.c  |  5 +++++
>  2 files changed, 31 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/mmc/card/block.c b/drivers/mmc/card/block.c
> index 1a3163f..988f16b 100644
> --- a/drivers/mmc/card/block.c
> +++ b/drivers/mmc/card/block.c
> @@ -1960,9 +1960,20 @@ 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);
> +		}
> +
>  		/* claim host only for the first request */
>  		mmc_get_card(card);
> +	}
>  
>  	ret = mmc_blk_part_switch(card, md);
>  	if (ret) {
> @@ -1999,7 +2010,7 @@ 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 +2018,19 @@ 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/core.c b/drivers/mmc/core/core.c
> index bf18b6b..9ab7020 100644
> --- a/drivers/mmc/core/core.c
> +++ b/drivers/mmc/core/core.c
> @@ -2400,6 +2400,7 @@ int mmc_detect_card_removed(struct mmc_host *host)
>  {
>  	struct mmc_card *card = host->card;
>  	int ret;
> +	unsigned long flags;
>  
>  	WARN_ON(!host->claimed);
>  
> @@ -2422,6 +2423,10 @@ int mmc_detect_card_removed(struct mmc_host *host)
>  			 * Schedule a detect work as soon as possible to let a
>  			 * rescan handle the card removal.
>  			 */
> +			spin_lock_irqsave(&host->lock, flags);
> +			host->rescan_disable = 0;
> +			spin_unlock_irqrestore(&host->lock, flags);
> +
>  			cancel_delayed_work(&host->detect);
>  			mmc_detect_change(host, 0);
>  		}

-- 
Thanks & Regards
Haijun.