On Sun, Mar 23, 2014 at 11:19 PM, Adrian Hunter <adrian.hunter@xxxxxxxxx> 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@xxxxxxxxxxxx>
>> ---
>> 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.
>
>> 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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