On 27 May 2013 09:51, Ulf Hansson <ulf.hansson@xxxxxxxxxx> wrote:
> On 26 May 2013 03:50, zhangfei gao <zhangfei.gao@xxxxxxxxx> wrote:
>>
>>
>>
>> On Fri, May 24, 2013 at 4:27 PM, Ulf Hansson <ulf.hansson@xxxxxxxxxx> wrote:
>>>
>>>
>>> >> Moreover, when the blk device is being suspended, we make sure the
>>> >> device
>>> >> will be runtime resumed. The reason for doing this is that we want the
>>> >> host suspend sequence to be unaware of any runtime power save
>>> >> operations
>>> >> done for the card in this phase. Thus it can just handle the suspend as
>>> >> the card is fully powered from a runtime perspective.
>>> >>
>>> >
>>> > If sd card is removed during system suspend, NULL pointer error would
>>> > happen
>>> > since card is removed.
>>>
>>> Why, where? Have you tested this patch, then maybe you can share a log?
>>>
>>> Myself has of course tested above scenario without observing any
>>> issues, though my environment could be different from yours.
>>>
>>> > mmc_detect_change would be called even CONFIG_MMC_UNSAFE_RESUME, so no
>>> > issue
>>> > without these patch.
>>>
>>> You need to elaborate why you see a concern here, I can not follow.
>>>
>>
>> Maybe I make misunderstood, or do some mistake.
>> since CONFIG_MMC_UNSAFE_RESUME has to be set, is that mean sd card can not
>> be unpluged with the feature enabled.
>> It can be reproduced here if unplug card in suspend or not.
>>
>> static void mmc_sd_detect(struct mmc_host *host)
>> {
>> err = _mmc_detect_card_removed(host);
>>
>> if (err) {
>> mmc_sd_remove(host);
>> /* host -> card is NULL now */
>> mmc_get_card(host->card);
>> }
>>
>
> I have no idea how you applied and tested this patch, but it seems
> like you have screwed it up. The above code is aligned with this
> patch.
Sorry, the above code is NOT aligned with the code in this patch.
>
> mmc_get_card is called before "err = _mmc_detect_card_removed(host)".
> And mmc_put_card, immediately after "err =
> _mmc_detect_card_removed(host)".
>
> Please consider re-applying the patch and re-test.
>
>
>> The log like:
>> [ 19.422655] mmc0: error -123 during resume (card was removed?)
>> [ 19.437750] PM: resume of devices complete after 100.698 msecs
>> [ 19.448780] mmc0: error -123 doing aggessive suspend
>> [ 19.559505] Unable to handle kernel NULL pointer dereference at virtual
>> address 00000000
>> [ 19.574547] pgd = c0004000
>> [ 19.579576] [00000000] *pgd=00000000
>> [ 19.586249] Internal error: Oops: 17 [#1] SMP ARM
>> [ 19.594971] CPU: 2 Not tainted (3.9.0-rc7-01026-g794b888-dirty #194)
>> [ 19.607400] PC is at mmc_get_card+0x44/0x6c
>> [ 19.615137] LR is at mmc_get_card+0x40/0x6c
>>
>> Thanks
>>
>
> Kind regards
> Ulf Hansson
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