Re: [PATCH v1 2/4] pinctrl: qcom: msm: Fix potential deadlock in pinmux configuration

[Praveen Talari <praveen.talari@oss.qualcomm.com>]

Hi Bjorn,

Thank you for review.

On 11/11/2025 9:38 AM, Bjorn Andersson wrote:
> On Mon, Nov 10, 2025 at 03:40:41PM +0530, Praveen Talari wrote:
>> Replace disable_irq() with disable_irq_nosync() in msm_pinmux_set_mux()
>> to prevent potential deadlock when wakeup IRQ is triggered on the same
> 
> "potential"? In what case will calling disable_irq() from the irq
> handler of that irq not deadlock?
> 
>> GPIO being reconfigured.
>>
>> The issue occurs when a wakeup IRQ is triggered on a GPIO and the IRQ
>> handler attempts to reconfigure the same GPIO's pinmux. In this scenario,
>> msm_pinmux_set_mux() calls disable_irq() which waits for the currently
>> running IRQ handler to complete, creating a circular dependency that
>> results in deadlock.
>>
>> Using disable_irq_nosync() avoids waiting for the IRQ handler to
>> complete, preventing the deadlock condition while still properly
>> disabling the interrupt during pinmux reconfiguration.
>>
>> Suggested-by: Prasad Sodagudi <prasad.sodagudi@oss.qualcomm.com>
> 
> That's weird, I debugged your deadlock for you and told you to make this
> very change in:
> 
> https://lore.kernel.org/all/7sxsfyu2kqbycyfftwfhrncwk3dfnubmzhyi2rqi3jtvi5qsnh@bya3cii45zhn/
> 
> So I guess Prasad told you how to fix this issue before I invested the
> time helping you?

Yes, that’s correct. Prasad had suggested it earlier.

Thanks,
Praveen Talari

> 
> 
> Change looks good, and description captures the problem.
> 
> Reviewed-by: Bjorn Andersson <andersson@kernel.org>
> 
> Regards,
> Bjorn
> 
>> Signed-off-by: Praveen Talari <praveen.talari@oss.qualcomm.com>
>> ---
>>   drivers/pinctrl/qcom/pinctrl-msm.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/drivers/pinctrl/qcom/pinctrl-msm.c b/drivers/pinctrl/qcom/pinctrl-msm.c
>> index 67525d542c5b..e99871b90ab9 100644
>> --- a/drivers/pinctrl/qcom/pinctrl-msm.c
>> +++ b/drivers/pinctrl/qcom/pinctrl-msm.c
>> @@ -189,7 +189,7 @@ static int msm_pinmux_set_mux(struct pinctrl_dev *pctldev,
>>   	 */
>>   	if (d && i != gpio_func &&
>>   	    !test_and_set_bit(d->hwirq, pctrl->disabled_for_mux))
>> -		disable_irq(irq);
>> +		disable_irq_nosync(irq);
>>   
>>   	raw_spin_lock_irqsave(&pctrl->lock, flags);
>>   
>> -- 
>> 2.34.1
>>