Re: [PATCH v5] driver core: enforce device_lock for driver_match_device()

[Marek Szyprowski <m.szyprowski@samsung.com>]

On 20.01.2026 14:22, Mark Brown wrote:
> On Wed, Jan 14, 2026 at 12:28:43AM +0800, Gui-Dong Han wrote:
>> Currently, driver_match_device() is called from three sites. One site
>> (__device_attach_driver) holds device_lock(dev), but the other two
>> (bind_store and __driver_attach) do not. This inconsistency means that
>> bus match() callbacks are not guaranteed to be called with the lock
>> held.
> I'm seeing boot hangs on Arm Juno in next/pending-fixes which bisect to
> this commit.  The boot grinds to a halt near the end of boot:
>
> [    2.570549] ledtrig-cpu: registered to indicate activity on CPUs
> [    2.618301] Serial: 8250/16550 driver, 4 ports, IRQ sharing enabled
> [    2.623547] msm_serial: driver initialized
> [    2.624058] SuperH (H)SCI(F) driver initialized
> [    2.624312] STM32 USART driver initialized
>
> with no further output, full log:
>
>     https://lava.sirena.org.uk/scheduler/job/2387335#L862
>
> We are also seeing similar looking boot hangs on some Qualcomm platforms
> in Arm's test lab which aren't verified to be the same thing but are
> hanging at a similar point in boot.

I've observed the same issue on Qualcomm RB5 board and bisecting lead me 
also to this patch. My kernel log also doesn't reveal much information:

...

[    3.671227] vreg_bob: Setting 3008000-4000000uV
[    3.676929] vreg_l1c_1p8: Setting 1800000-1800000uV
[    3.682826] vreg_l2c_1p2: Setting 1200000-1200000uV
[    3.688547] vreg_l3c_0p8: Setting 800000-800000uV
[    3.694080] vreg_l4c_1p7: Setting 1704000-2928000uV
[    3.699908] vreg_l5c_1p8: Setting 1800000-2928000uV
[    3.705763] vreg_l6c_2p96: Setting 1800000-2960000uV
[    3.711684] vreg_l7c_cam_vcm0_2p85: Setting 2856000-3104000uV
[    3.718408] vreg_l8c_1p8: Setting 1800000-1800000uV
[    3.724287] vreg_l9c_2p96: Setting 2704000-2960000uV
[    3.730218] vreg_l10c_3p0: Setting 3000000-3000000uV
[    3.736226] vreg_l11c_3p3: Setting 3296000-3296000uV
[    3.743413] vreg_s8c_1p3: Setting 1352000-1352000uV
[    3.771370] Serial: 8250/16550 driver, 4 ports, IRQ sharing enabled
[    3.792020] msm_serial: driver initialized
[    3.797633] SuperH (H)SCI(F) driver initialized
[    3.802881] STM32 USART driver initialized

[hang/freeze]

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland