Re: [PATCH v2][next] tty: sunsu: Simplify device_node cleanup by using __free

From: Ilpo Järvinen
Date: Thu May 02 2024 - 12:05:58 EST


On Wed, 1 May 2024, Shresth Prasad wrote:

> Add `__free` function attribute to `ap` and `match` pointer
> initialisations which ensure that the pointers are freed as soon as they
> go out of scope, thus removing the need to manually free them using
> `of_node_put`.
>
> This also removes the need for the `goto` statement and the `rc`
> variable.
>
> Tested using a qemu x86_64 virtual machine.

Eh, how can you test this with an x86_64 VM ???

config SERIAL_SUNSU
tristate "Sun SU serial support"
depends on SPARC && PCI

--
i.


> Suggested-by: Julia Lawall <julia.lawall@xxxxxxxx>
> Signed-off-by: Shresth Prasad <shresthprasad7@xxxxxxxxx>
> ---
> Changes in v2:
> - Specify how the patch was tested
>
> drivers/tty/serial/sunsu.c | 37 +++++++++++--------------------------
> 1 file changed, 11 insertions(+), 26 deletions(-)
>
> diff --git a/drivers/tty/serial/sunsu.c b/drivers/tty/serial/sunsu.c
> index 67a5fc70bb4b..0f463da5e7ce 100644
> --- a/drivers/tty/serial/sunsu.c
> +++ b/drivers/tty/serial/sunsu.c
> @@ -1382,44 +1382,29 @@ static inline struct console *SUNSU_CONSOLE(void)
>
> static enum su_type su_get_type(struct device_node *dp)
> {
> - struct device_node *ap = of_find_node_by_path("/aliases");
> - enum su_type rc = SU_PORT_PORT;
> + struct device_node *ap __free(device_node) =
> + of_find_node_by_path("/aliases");
>
> if (ap) {
> const char *keyb = of_get_property(ap, "keyboard", NULL);
> const char *ms = of_get_property(ap, "mouse", NULL);
> - struct device_node *match;
>
> if (keyb) {
> - match = of_find_node_by_path(keyb);
> + struct device_node *match __free(device_node) =
> + of_find_node_by_path(keyb);
>
> - /*
> - * The pointer is used as an identifier not
> - * as a pointer, we can drop the refcount on
> - * the of__node immediately after getting it.
> - */
> - of_node_put(match);
> -
> - if (dp == match) {
> - rc = SU_PORT_KBD;
> - goto out;
> - }
> + if (dp == match)
> + return SU_PORT_KBD;
> }
> if (ms) {
> - match = of_find_node_by_path(ms);
> + struct device_node *match __free(device_node) =
> + of_find_node_by_path(ms);
>
> - of_node_put(match);
> -
> - if (dp == match) {
> - rc = SU_PORT_MS;
> - goto out;
> - }
> + if (dp == match)
> + return SU_PORT_MS;
> }
> }
> -
> -out:
> - of_node_put(ap);
> - return rc;
> + return SU_PORT_PORT;
> }
>
> static int su_probe(struct platform_device *op)
>