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SubjectRe: [PATCH v2 2/2] hwmon: nzxt-smart2: add a check of devm_add_action in nzxt_smart2_hid_probe
On 2/26/23 19:09, void0red wrote:
> From: Kang Chen <void0red@gmail.com>
>
> devm_add_action may fails, check it and return early.
>
> Signed-off-by: Kang Chen <void0red@gmail.com>
> ---
> v2 -> v1: split the patch
>
> drivers/hwmon/nzxt-smart2.c | 4 +++-
> 1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/hwmon/nzxt-smart2.c b/drivers/hwmon/nzxt-smart2.c
> index 2b93ba896..725974cb3 100644
> --- a/drivers/hwmon/nzxt-smart2.c
> +++ b/drivers/hwmon/nzxt-smart2.c
> @@ -737,8 +737,10 @@ static int nzxt_smart2_hid_probe(struct hid_device *hdev,
> init_waitqueue_head(&drvdata->wq);
>
> mutex_init(&drvdata->mutex);
> - devm_add_action(&hdev->dev, (void (*)(void *))mutex_destroy,
> + ret = devm_add_action(&hdev->dev, (void (*)(void *))mutex_destroy,
> &drvdata->mutex);

Please watch for multi-line alignment. Also, turns out the original
code is wrong: Type casting a function pointer argument like this,
while it typically works in practice, is undefined in C. The function
pointer passed to devm_add_action() needs to point to a local
function with void * argument, and that function needs to call
mutex_destroy() with the same argument. Also, based on the context,
this needs to call devm_add_action_or_reset() to ensure that
the destroy function is called on error.

Thanks,
Guenter

> + if (ret)
> + return ret;
>
> ret = hid_parse(hdev);
> if (ret)

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