On 26 May 2013 03:50, zhangfei gao <zhangfei....@gmail.com> wrote:
>
>
>
> On Fri, May 24, 2013 at 4:27 PM, Ulf Hansson <ulf.hans...@linaro.org> 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.
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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