linux-kernel - Re: [PATCH v2 1/3] gpiolib: don't crash on enabling GPIO HOG pins

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Message-ID: <CACRpkdaErq4uwjjqug3BbiHMKbP=4PkzpXPuQ57+2mgjJQ7ACQ@mail.gmail.com>
Date: Wed, 14 May 2025 00:18:41 +0200
From: Linus Walleij <linus.walleij@...aro.org>
To: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>
Cc: Bjorn Andersson <andersson@...nel.org>, Guenter Roeck <linux@...ck-us.net>, 
	Josh Cartwright <joshc@...eaurora.org>, Bartosz Golaszewski <bartosz.golaszewski@...aro.org>, 
	Matti Vaittinen <mazziesaccount@...il.com>, Doug Anderson <dianders@...omium.org>, 
	Bartosz Golaszewski <brgl@...ev.pl>, linux-arm-msm@...r.kernel.org, linux-gpio@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 1/3] gpiolib: don't crash on enabling GPIO HOG pins

On Tue, May 13, 2025 at 8:39 PM Dmitry Baryshkov
<dmitry.baryshkov@....qualcomm.com> wrote:

> On Qualcomm platforms if the board uses GPIO hogs msm_pinmux_request()
> calls gpiochip_line_is_valid(). After commit 8015443e24e7 ("gpio: Hide
> valid_mask from direct assignments") gpiochip_line_is_valid() uses
> gc->gpiodev, which is NULL when GPIO hog pins are being processed.
> Thus after this commit using GPIO hogs causes the following crash. In
> order to fix this, verify that gc->gpiodev is not NULL.
>
> Note: it is not possible to reorder calls (e.g. by calling
> msm_gpio_init() before pinctrl registration or by splitting
> pinctrl_register() into _and_init() and pinctrl_enable() and calling the
> latter function after msm_gpio_init()) because GPIO chip registration
> would fail with EPROBE_DEFER if pinctrl is not enabled at the time of
> registration.
>
> pc : gpiochip_line_is_valid+0x4/0x28
> lr : msm_pinmux_request+0x24/0x40
> sp : ffff8000808eb870
> x29: ffff8000808eb870 x28: 0000000000000000 x27: 0000000000000000
> x26: 0000000000000000 x25: ffff726240f9d040 x24: 0000000000000000
> x23: ffff7262438c0510 x22: 0000000000000080 x21: ffff726243ea7000
> x20: ffffab13f2c4e698 x19: 0000000000000080 x18: 00000000ffffffff
> x17: ffff726242ba6000 x16: 0000000000000100 x15: 0000000000000028
> x14: 0000000000000000 x13: 0000000000002948 x12: 0000000000000003
> x11: 0000000000000078 x10: 0000000000002948 x9 : ffffab13f50eb5e8
> x8 : 0000000003ecb21b x7 : 000000000000002d x6 : 0000000000000b68
> x5 : 0000007fffffffff x4 : ffffab13f52f84a8 x3 : ffff8000808eb804
> x2 : ffffab13f1de8190 x1 : 0000000000000080 x0 : 0000000000000000
> Call trace:
>  gpiochip_line_is_valid+0x4/0x28 (P)
>  pin_request+0x208/0x2c0
>  pinmux_enable_setting+0xa0/0x2e0
>  pinctrl_commit_state+0x150/0x26c
>  pinctrl_enable+0x6c/0x2a4
>  pinctrl_register+0x3c/0xb0
>  devm_pinctrl_register+0x58/0xa0
>  msm_pinctrl_probe+0x2a8/0x584
>  sdm845_pinctrl_probe+0x20/0x88
>  platform_probe+0x68/0xc0
>  really_probe+0xbc/0x298
>  __driver_probe_device+0x78/0x12c
>  driver_probe_device+0x3c/0x160
>  __device_attach_driver+0xb8/0x138
>  bus_for_each_drv+0x84/0xe0
>  __device_attach+0x9c/0x188
>  device_initial_probe+0x14/0x20
>  bus_probe_device+0xac/0xb0
>  deferred_probe_work_func+0x8c/0xc8
>  process_one_work+0x208/0x5e8
>  worker_thread+0x1b4/0x35c
>  kthread+0x144/0x220
>  ret_from_fork+0x10/0x20
> Code: b5fffba0 17fffff2 9432ec27 f9400400 (f9428800)
>
> Fixes: 8015443e24e7 ("gpio: Hide valid_mask from direct assignments")
> Reported-by: Doug Anderson <dianders@...omium.org>
> Closes: https://lore.kernel.org/r/CAD=FV=Vg8_ZOLgLoC4WhFPzhVsxXFC19NrF38W6cW_W_3nFjbw@mail.gmail.com
> Tested-by: Douglas Anderson <dianders@...omium.org>
> Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@....qualcomm.com>

(...)
> +       /*
> +        * hog pins are requested before registering GPIO chip
> +        */
> +       if (!gc->gpiodev)
> +               return true;

LGTM, Bartosz if it's fine with you as well can you ACK this and I'll
stick the patches in fixes and get it to Torvalds pronto.

Yours,
Linus Walleij