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

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Message-ID: <CACRpkdYEbxtjoi8KQxS5fY6xr3UZwQmG-yKvT3L8fRcCXDaAwQ@mail.gmail.com>
Date: Wed, 12 Nov 2025 13:43:30 +0100
From: Linus Walleij <linus.walleij@...aro.org>
To: Praveen Talari <praveen.talari@....qualcomm.com>
Cc: Bjorn Andersson <andersson@...nel.org>, Konrad Dybcio <konradybcio@...nel.org>, 
	Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>, Jiri Slaby <jirislaby@...nel.org>, 
	Dmitry Baryshkov <lumag@...nel.org>, linux-arm-msm@...r.kernel.org, 
	devicetree@...r.kernel.org, linux-kernel@...r.kernel.org, 
	linux-gpio@...r.kernel.org, linux-serial@...r.kernel.org, 
	alexey.klimov@...aro.org, krzk@...nel.org, bryan.odonoghue@...aro.org, 
	jorge.ramirez@....qualcomm.com, dmitry.baryshkov@....qualcomm.com, 
	Konrad Dybcio <konrad.dybcio@....qualcomm.com>, psodagud@...cinc.com, djaggi@...cinc.com, 
	quic_msavaliy@...cinc.com, quic_vtanuku@...cinc.com, 
	quic_arandive@...cinc.com, quic_shazhuss@...cinc.com, 
	quic_cchiluve@...cinc.com, Prasad Sodagudi <prasad.sodagudi@....qualcomm.com>
Subject: Re: [PATCH v1 2/4] pinctrl: qcom: msm: Fix potential deadlock in
 pinmux configuration

Hi Praveen,

thanks for your patch!

On Mon, Nov 10, 2025 at 11:11 AM Praveen Talari
<praveen.talari@....qualcomm.com> 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
> 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@....qualcomm.com>
> Signed-off-by: Praveen Talari <praveen.talari@....qualcomm.com>

I applied this patch 2/4 to the pin control tree for fixes.

I removed the word "potential" from subject and text so as to
reflect what Bjorn is saying: it's a very real issue.

Thanks for fixing this!
Linus Walleij