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SubjectRe: [PATCH V2] mmc: sdhci: don't read cd-gpio while holding spinlock
On 24.03.2014 18:18, Andrew Bresticker wrote:
> On Sun, Mar 23, 2014 at 11:19 PM, Adrian Hunter <adrian.hunter@intel.com> wrote:
>> On 24.03.2014 03:43, Andrew Bresticker wrote:
>>> sdhci_request() and sdhci_card_event() read the cd-gpio via
>>> mmc_gpio_get_cd(), which can sleep, while holding host->lock.
>>> This may result in the following BUG:
>>>
>>> BUG: spinlock wrong CPU on CPU#2, kworker/u8:16/4296
>>> lock: 0xea6b9c80, .magic: dead4ead, .owner: kworker/u8:16/4296, .owner_cpu: 0
>>> CPU: 2 PID: 4296 Comm: kworker/u8:16 Tainted: G C 3.10.18 #137
>>> Workqueue: kmmcd mmc_rescan
>>> [<8020cf8c>] (unwind_backtrace+0x0/0x118) from [<8020a0c8>] (show_stack+0x20/0x24)
>>> [<8020a0c8>] (show_stack+0x20/0x24) from [<8075e5b8>] (dump_stack+0x20/0x28)
>>> [<8075e5b8>] (dump_stack+0x20/0x28) from [<804184a8>] (spin_dump+0x80/0x94)
>>> [<804184a8>] (spin_dump+0x80/0x94) from [<804184e8>] (spin_bug+0x2c/0x30)
>>> [<804184e8>] (spin_bug+0x2c/0x30) from [<80418790>] (do_raw_spin_unlock+0x94/0xd4)
>>> [<80418790>] (do_raw_spin_unlock+0x94/0xd4) from [<80761a44>] (_raw_spin_unlock_irqrestore+0x1c/0x24)
>>> [<80761a44>] (_raw_spin_unlock_irqrestore+0x1c/0x24) from [<805ff66c>] (sdhci_request+0x1c8/0x1d0)
>>> [<805ff66c>] (sdhci_request+0x1c8/0x1d0) from [<805ebb5c>] (mmc_start_request+0xec/0xf4)
>>> [<805ebb5c>] (mmc_start_request+0xec/0xf4) from [<805ebcbc>] (mmc_wait_for_req+0x80/0xf4)
>>> ...
>>>
>>> Read the cd-gpio before acquiring the spinlock instead.
>>>
>>> Signed-off-by: Andrew Bresticker <abrestic@chromium.org>
>>> ---
>>> drivers/mmc/host/sdhci.c | 7 ++++---
>>> 1 file changed, 4 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
>>> index 04a5e25..328b250 100644
>>> --- a/drivers/mmc/host/sdhci.c
>>> +++ b/drivers/mmc/host/sdhci.c
>>> @@ -1340,6 +1340,7 @@ static void sdhci_request(struct mmc_host *mmc, struct mmc_request *mrq)
>>> u32 tuning_opcode;
>>>
>>> host = mmc_priv(mmc);
>>> + present = mmc_gpio_get_cd(host->mmc);
>>>
>>> sdhci_runtime_pm_get(host);
>>>
>>> @@ -1371,7 +1372,6 @@ static void sdhci_request(struct mmc_host *mmc, struct mmc_request *mrq)
>>> * zero: cd-gpio is used, and card is removed
>>> * one: cd-gpio is used, and card is present
>>> */
>>> - present = mmc_gpio_get_cd(host->mmc);
>>> if (present < 0) {
>>> /* If polling, assume that the card is always present. */
>>> if (host->quirks & SDHCI_QUIRK_BROKEN_CARD_DETECTION)
>>> @@ -2082,15 +2082,16 @@ static void sdhci_card_event(struct mmc_host *mmc)
>>> {
>>> struct sdhci_host *host = mmc_priv(mmc);
>>> unsigned long flags;
>>> + int present;
>>>
>>> /* First check if client has provided their own card event */
>>> if (host->ops->card_event)
>>> host->ops->card_event(host);
>>>
>>> + present = sdhci_get_cd(mmc);
>>
>> Shouldn't that be sdhci_do_get_cd(mmc) ?
>
> No I do mean shdic_get_cd(). We might be runtime suspended so we need
> sdhci_get_cd() to increment the device usage count and do a runtime
> resume if necessary.

Very true.

Acked-by: Adrian Hunter <adrian.hunter@intel.com>

>
>>
>>> spin_lock_irqsave(&host->lock, flags);
>>>
>>> - /* Check host->mrq first in case we are runtime suspended */
>>> - if (host->mrq && !sdhci_do_get_cd(host)) {
>>> + if (host->mrq && !present) {
>>> pr_err("%s: Card removed during transfer!\n",
>>> mmc_hostname(host->mmc));
>>> pr_err("%s: Resetting controller.\n",
>>>
>>
>
>



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