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

[Bjorn Andersson]

On Tue, Nov 11, 2025 at 10:52:25AM +0530, Praveen Talari wrote:
> 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@xxxxxxxxxxxxxxxx>
> > 
> > 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.
> 

Okay, then this patch looks good.

Regards,
Bjorn

> Thanks,
> Praveen Talari
> 
> > 
> > 
> > Change looks good, and description captures the problem.
> > 
> > Reviewed-by: Bjorn Andersson <andersson@xxxxxxxxxx>
> > 
> > Regards,
> > Bjorn
> > 
> > > Signed-off-by: Praveen Talari <praveen.talari@xxxxxxxxxxxxxxxx>
> > > ---
> > >   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
> > >