linux-kernel - Re: [PATCH v4 00/10] gpio: improve support for shared GPIOs

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <CAMRc=Me8KUGD7Lmdr7iecXWG4JD2cS8i37P+oMxQYdSZ4zAUEA@mail.gmail.com>
Date: Wed, 26 Nov 2025 17:49:59 +0100
From: Bartosz Golaszewski <brgl@...ev.pl>
To: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
Cc: Kees Cook <kees@...nel.org>, Mika Westerberg <westeri@...nel.org>, 
	Dmitry Torokhov <dmitry.torokhov@...il.com>, Andrew Morton <akpm@...ux-foundation.org>, 
	Linus Walleij <linus.walleij@...aro.org>, Manivannan Sadhasivam <mani@...nel.org>, 
	Rob Herring <robh@...nel.org>, Krzysztof Kozlowski <krzk+dt@...nel.org>, Conor Dooley <conor+dt@...nel.org>, 
	Saravana Kannan <saravanak@...gle.com>, Greg Kroah-Hartman <gregkh@...uxfoundation.org>, 
	Andy Shevchenko <andy@...nel.org>, Catalin Marinas <catalin.marinas@....com>, Will Deacon <will@...nel.org>, 
	Srinivas Kandagatla <srini@...nel.org>, Liam Girdwood <lgirdwood@...il.com>, Mark Brown <broonie@...nel.org>, 
	Jaroslav Kysela <perex@...ex.cz>, Takashi Iwai <tiwai@...e.com>, 
	Alexey Klimov <alexey.klimov@...aro.org>, Bjorn Andersson <andersson@...nel.org>, 
	Konrad Dybcio <konradybcio@...nel.org>, linux-hardening@...r.kernel.org, 
	linux-kernel@...r.kernel.org, linux-gpio@...r.kernel.org, 
	linux-arm-kernel@...ts.infradead.org, linux-sound@...r.kernel.org, 
	linux-arm-msm@...r.kernel.org, 
	Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
Subject: Re: [PATCH v4 00/10] gpio: improve support for shared GPIOs

On Wed, Nov 26, 2025 at 5:27 PM Dmitry Baryshkov
<dmitry.baryshkov@....qualcomm.com> wrote:
>
> I'm sorry if this was already reported and fixed. On Qualcomm RB5
> platform with this patchset in place I'm getting the following backtrace
> (and then a lockup):
>
> [    4.298346] gpiolib_shared: GPIO 130 owned by f100000.pinctrl is shared by multiple consumers
> [    4.307157] gpiolib_shared: Setting up a shared GPIO entry for speaker@0,3
> [    4.314604]
> [    4.316146] ============================================
> [    4.321600] WARNING: possible recursive locking detected
> [    4.327054] 6.18.0-rc7-next-20251125-g3f300d0674f6-dirty #3887 Not tainted
> [    4.334115] --------------------------------------------
> [    4.339566] kworker/u32:3/71 is trying to acquire lock:
> [    4.344931] ffffda019ba71850 (gpio_shared_lock){+.+.}-{4:4}, at: devm_gpiod_shared_get+0x34/0x2e0
> [    4.354057]
> [    4.354057] but task is already holding lock:
> [    4.360041] ffffda019ba71850 (gpio_shared_lock){+.+.}-{4:4}, at: gpio_device_setup_shared+0x30/0x268
> [    4.369421]

Ah, I missed the use-case where the auxiliary device is bound right
after it gets added and we're still holding the shared_gpio_lock. I
think we should prepare the proxy devices but only add them after
releasing the lock. I will fix it first thing tomorrow morning.

Bartosz