Re: [patch V3 01/10] cleanup: Provide retain_ptr()

James Bottomley
2025-03-17T13:57:32Z

On Mon, 2025-03-17 at 14:29 +0100, Thomas Gleixner wrote:
[...]
> +/*
> + * Only for situations where an allocation is handed in to another
> function
> + * and consumed by that function on success.
> + *
> + * struct foo *f __free(kfree) = kzalloc(sizeof(*f),
> GFP_KERNEL);
> + *
> + * setup(f);
> + * if (some_condition)
> + * return -EINVAL;
> + * ....
> + * ret = bar(f);
> + * if (!ret)
> + * retain_ptr(f);
> + * return ret;
> + */
> +#define retain_ptr(p) \
> + __get_and_null(p, NULL)

This doesn't score very highly on the Rusty API design scale because it
can be used anywhere return_ptr() should be used. To force the
distinction between the two cases at the compiler level, should there
be a cast to void in the above to prevent using the return value?

Regards,

James