linux-kernel - Re: [PATCH] mmc: sdhci: fix possible scheduling while atomic

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Date:	Fri, 17 Jan 2014 15:11:59 -0800
From:	John Tobias <john.tobias.ph@...il.com>
To:	Philip Rakity <prakity@...dia.com>
Cc:	Andrew Bresticker <abrestic@...omium.org>,
	Chris Ball <chris@...ntf.net>,
	"linux-mmc@...r.kernel.org" <linux-mmc@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] mmc: sdhci: fix possible scheduling while atomic

There's an existing patch for that...
http://www.spinics.net/lists/arm-kernel/msg296596.html

On Fri, Jan 17, 2014 at 2:58 PM, Philip Rakity <prakity@...dia.com> wrote:
>
> On Jan 17, 2014, at 7:57 PM, Andrew Bresticker <abrestic@...omium.org> wrote:
>
>> sdhci_execute_tuning() takes host->lock without disabling interrupts.
>> Use spin_lock_irq{save,restore} instead so that we avoid taking an
>> interrupt and scheduling while holding host->lock.
>>
>> Signed-off-by: Andrew Bresticker <abrestic@...omium.org>
>> ---
>> drivers/mmc/host/sdhci.c | 13 +++++++------
>> 1 file changed, 7 insertions(+), 6 deletions(-)
>>
>> diff --git a/drivers/mmc/host/sdhci.c b/drivers/mmc/host/sdhci.c
>> index ec3eb30..84c80e7 100644
>> --- a/drivers/mmc/host/sdhci.c
>> +++ b/drivers/mmc/host/sdhci.c
>> @@ -1857,12 +1857,13 @@ static int sdhci_execute_tuning(struct mmc_host *mmc, u32 opcode)
>>       unsigned long timeout;
>>       int err = 0;
>>       bool requires_tuning_nonuhs = false;
>> +     unsigned long flags;
>>
>>       host = mmc_priv(mmc);
>>
>>       sdhci_runtime_pm_get(host);
>>       disable_irq(host->irq);
>> -     spin_lock(&host->lock);
>> +     spin_lock_irqsave(&host->lock, flags);
>
>
> The disable_irq() call stops the controller from doing interrupts.
> Please explain what problem you are seeing
>
>>
>>       ctrl = sdhci_readw(host, SDHCI_HOST_CONTROL2);
>>
>> @@ -1882,14 +1883,14 @@ static int sdhci_execute_tuning(struct mmc_host *mmc, u32 opcode)
>>           requires_tuning_nonuhs)
>>               ctrl |= SDHCI_CTRL_EXEC_TUNING;
>>       else {
>> -             spin_unlock(&host->lock);
>> +             spin_unlock_irqrestore(&host->lock, flags);
>>               enable_irq(host->irq);
>>               sdhci_runtime_pm_put(host);
>>               return 0;
>>       }
>>
>>       if (host->ops->platform_execute_tuning) {
>> -             spin_unlock(&host->lock);
>> +             spin_unlock_irqrestore(&host->lock, flags);
>>               enable_irq(host->irq);
>>               err = host->ops->platform_execute_tuning(host, opcode);
>>               sdhci_runtime_pm_put(host);
>> @@ -1963,7 +1964,7 @@ static int sdhci_execute_tuning(struct mmc_host *mmc, u32 opcode)
>>               host->cmd = NULL;
>>               host->mrq = NULL;
>>
>> -             spin_unlock(&host->lock);
>> +             spin_unlock_irqrestore(&host->lock, flags);
>>               enable_irq(host->irq);
>>
>>               /* Wait for Buffer Read Ready interrupt */
>> @@ -1971,7 +1972,7 @@ static int sdhci_execute_tuning(struct mmc_host *mmc, u32 opcode)
>>                                       (host->tuning_done == 1),
>>                                       msecs_to_jiffies(50));
>>               disable_irq(host->irq);
>> -             spin_lock(&host->lock);
>> +             spin_lock_irqsave(&host->lock, flags);
>>
>>               if (!host->tuning_done) {
>>                       pr_info(DRIVER_NAME ": Timeout waiting for "
>> @@ -2046,7 +2047,7 @@ out:
>>               err = 0;
>>
>>       sdhci_clear_set_irqs(host, SDHCI_INT_DATA_AVAIL, ier);
>> -     spin_unlock(&host->lock);
>> +     spin_unlock_irqrestore(&host->lock, flags);
>>       enable_irq(host->irq);
>>       sdhci_runtime_pm_put(host);
>>
>> --
>> 1.8.5.2
>>
>> --
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>
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