[PATCH] drm/meson: fix shutdown crash when component not probed

[Martin Blumenstingl]

On Fri, Apr 30, 2021 at 10:28 AM Neil Armstrong <narmstrong at baylibre.com> wrote:
>
> When main component is not probed, by example when the dw-hdmi module is
> not loaded yet or in probe defer, the following crash appears on shutdown:
>
> Unable to handle kernel NULL pointer dereference at virtual address 0000000000000038
> ...
> pc : meson_drv_shutdown+0x24/0x50
> lr : platform_drv_shutdown+0x20/0x30
> ...
> Call trace:
> meson_drv_shutdown+0x24/0x50
> platform_drv_shutdown+0x20/0x30
> device_shutdown+0x158/0x360
> kernel_restart_prepare+0x38/0x48
> kernel_restart+0x18/0x68
> __do_sys_reboot+0x224/0x250
> __arm64_sys_reboot+0x24/0x30
> ...
>
> Simply check if the priv struct has been allocated before using it.
>
> Fixes: fa0c16caf3d7 ("drm: meson_drv add shutdown function")
> Reported-by: Stefan Agner <stefan at agner.ch>
> Signed-off-by: Neil Armstrong <narmstrong at baylibre.com>
Tested-by: Martin Blumenstingl <martin.blumenstingl at googlemail.com>