Re: [RESEND PATCH V3] mmc: core: Detect card removal on I/O error

[Ulf Hansson <ulf.hansson@stericsson.com>]

Namjae Jeon wrote:
> 2012/2/3 Jaehoon Chung <jh80.chung@samsung.com>:
>> On 02/03/2012 06:33 PM, Ulf Hansson wrote:
>>
>>> To prevent I/O as soon as possible at card removal, a new
>>> detect work is re-scheduled without a delay to let a rescan
>>> remove the card device as soon a possible.
>>>
>>> Additionally, MMC_CAP2_DETECT_ON_ERR can now be used to handle
>>> "slowly" removed cards that a scheduled detect work did not
>>> detect as removed. To prevent further I/O requests for these
>>> lingering removed cards, check if card has been removed and then
>>> schedule a detect work to properly remove it.
>>>
>>> Signed-off-by: Ulf Hansson <ulf.hansson@stericsson.com>
>>> ---
>>>
>>> Changes in v3:
>>>       - Check for card is NULL and minor code simplifications.
>>>
>>> Changes in v2:
>>>       - Updated according to review comments.
>>>       - Merging two patches for this feature into one.
>>>
>>> ---
>>>  drivers/mmc/core/core.c  |   24 +++++++++++++++++++++---
>>>  include/linux/mmc/host.h |    1 +
>>>  2 files changed, 22 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
>>> index bec0bf2..9645e8c 100644
>>> --- a/drivers/mmc/core/core.c
>>> +++ b/drivers/mmc/core/core.c
>>> @@ -2077,18 +2077,36 @@ int _mmc_detect_card_removed(struct mmc_host *host)
>>>  int mmc_detect_card_removed(struct mmc_host *host)
>>>  {
>>>       struct mmc_card *card = host->card;
>>> +     int ret;
>>>
>>>       WARN_ON(!host->claimed);
>>> +
>>> +     if (!card)
>>> +             return 1;
>>> +
>>> +     ret = mmc_card_removed(card);
>> this function called mmc_detect_card_removed(card->host) in block.c.
>> then card isn't NULL..isn't?
>> Just wondering... :)

Yes, if called from block device thread (block.c) card is always present.

> If we think this function is used anywhere else next time, it is reasonable.
> And old code also checked null.

That is why I also agree that this should be checked. It is an exported 
function and who know if it is going to used from some other context in 
future.

>> Best Regards,
>> Jaehoon Chung
>>
>>>       /*
>>>        * The card will be considered unchanged unless we have been asked to
>>>        * detect a change or host requires polling to provide card detection.
>>>        */
>>> -     if (card && !host->detect_change && !(host->caps & MMC_CAP_NEEDS_POLL))
>>> -             return mmc_card_removed(card);
>>> +     if (!host->detect_change && !(host->caps & MMC_CAP_NEEDS_POLL) &&
>>> +         !(host->caps2 & MMC_CAP2_DETECT_ON_ERR))
>>> +             return ret;
>>>
>>>       host->detect_change = 0;
>>> +     if (!ret) {
>>> +             ret = _mmc_detect_card_removed(host);
>>> +             if (ret) {
>>> +                     /*
>>> +                      * Schedule a detect work as soon as possible to let a
>>> +                      * rescan handle the card removal.
>>> +                      */
>>> +                     cancel_delayed_work(&host->detect);
>>> +                     mmc_detect_change(host, 0);
>>> +             }
>>> +     }
>>>
>>> -     return _mmc_detect_card_removed(host);
>>> +     return ret;
>>>  }
>>>  EXPORT_SYMBOL(mmc_detect_card_removed);
>>>
>>> diff --git a/include/linux/mmc/host.h b/include/linux/mmc/host.h
>>> index dd13e05..368a2b9 100644
>>> --- a/include/linux/mmc/host.h
>>> +++ b/include/linux/mmc/host.h
>>> @@ -257,6 +257,7 @@ struct mmc_host {
>>>  #define MMC_CAP2_HS200_1_2V_SDR      (1 << 6)        /* can support */
>>>  #define MMC_CAP2_HS200               (MMC_CAP2_HS200_1_8V_SDR | \
>>>                                MMC_CAP2_HS200_1_2V_SDR)
>>> +#define MMC_CAP2_DETECT_ON_ERR       (1 << 7)        /* On I/O err check card removal */
>>>
>>>       mmc_pm_flag_t           pm_caps;        /* supported pm features */
>>>       unsigned int        power_notify_type;
>>
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