[PATCH] drm/bridge: megachips: Fix error handling in i2c_register_driver()
Andrzej Hajda
andrzej.hajda at intel.com
Tue Nov 8 08:50:00 UTC 2022
On 08.11.2022 09:29, Yuan Can wrote:
> A problem about insmod megachips-stdpxxxx-ge-b850v3-fw.ko failed is
> triggered with the following log given:
>
> [ 4497.981497] Error: Driver 'stdp4028-ge-b850v3-fw' is already registered, aborting...
> insmod: ERROR: could not insert module megachips-stdpxxxx-ge-b850v3-fw.ko: Device or resource busy
>
> The reason is that stdpxxxx_ge_b850v3_init() returns i2c_add_driver()
> directly without checking its return value, if i2c_add_driver() failed,
> it returns without calling i2c_del_driver() on the previous i2c driver,
> resulting the megachips-stdpxxxx-ge-b850v3-fw can never be installed
> later.
> A simple call graph is shown as below:
>
> stdpxxxx_ge_b850v3_init()
> i2c_add_driver(&stdp4028_ge_b850v3_fw_driver)
> i2c_add_driver(&stdp2690_ge_b850v3_fw_driver)
> i2c_register_driver()
> driver_register()
> bus_add_driver()
> priv = kzalloc(...) # OOM happened
> # return without delete stdp4028_ge_b850v3_fw_driver
>
> Fix by calling i2c_del_driver() on stdp4028_ge_b850v3_fw_driver when
> i2c_add_driver() returns error.
>
> Fixes: fcfa0ddc18ed ("drm/bridge: Drivers for megachips-stdpxxxx-ge-b850v3-fw (LVDS-DP++)")
> Signed-off-by: Yuan Can <yuancan at huawei.com>
> ---
> drivers/gpu/drm/bridge/megachips-stdpxxxx-ge-b850v3-fw.c | 8 +++++++-
> 1 file changed, 7 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/bridge/megachips-stdpxxxx-ge-b850v3-fw.c b/drivers/gpu/drm/bridge/megachips-stdpxxxx-ge-b850v3-fw.c
> index 97359f807bfc..0d037eeefcf3 100644
> --- a/drivers/gpu/drm/bridge/megachips-stdpxxxx-ge-b850v3-fw.c
> +++ b/drivers/gpu/drm/bridge/megachips-stdpxxxx-ge-b850v3-fw.c
> @@ -440,7 +440,13 @@ static int __init stdpxxxx_ge_b850v3_init(void)
> if (ret)
> return ret;
>
> - return i2c_add_driver(&stdp2690_ge_b850v3_fw_driver);
> + ret = i2c_add_driver(&stdp2690_ge_b850v3_fw_driver);
> + if (ret) {
> + i2c_del_driver(&stdp4028_ge_b850v3_fw_driver);
> + return ret;
> + }
> +
> + return 0;
Could be:
ret = i2c_add_driver(&stdp2690_ge_b850v3_fw_driver);
if (ret)
i2c_del_driver(&stdp4028_ge_b850v3_fw_driver);
return ret;
Up to you. Anyway:
Reviewed-by: Andrzej Hajda <andrzej.hajda at intel.com>
Regards
Andrzej
> }
> module_init(stdpxxxx_ge_b850v3_init);
>
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