linux-kernel - Re: [PATCH v2][next] tty: sunsu: Simplify device_node cleanup by using _

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Date: Thu, 2 May 2024 09:56:00 +0200
From: Jiri Slaby <jirislaby@...nel.org>
To: Shresth Prasad <shresthprasad7@...il.com>, davem@...emloft.net,
 gregkh@...uxfoundation.org
Cc: sparclinux@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-serial@...r.kernel.org, javier.carrasco.cruz@...il.com,
 skhan@...uxfoundation.org, Julia Lawall <julia.lawall@...ia.fr>
Subject: Re: [PATCH v2][next] tty: sunsu: Simplify device_node cleanup by
 using __free

On 01. 05. 24, 10:41, 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.
> 
> Suggested-by: Julia Lawall <julia.lawall@...ia.fr>
> Signed-off-by: Shresth Prasad <shresthprasad7@...il.com>
> ---
> Changes in v2:
>      - Specify how the patch was tested
> 
>   drivers/tty/serial/sunsu.c | 37 +++++++++++--------------------------
>   1 file changed, 11 insertions(+), 26 deletions(-)

Nice cleanup.

> --- 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 we used c++, that would be even nicer; like:
Destroyer ap(of_find_node_by_path("/aliases"));

But we don't :P. OTOH. can't we achieve that with macro-fu and typeof() 
magic? Perhaps not really exactly the above, but something like
   Destroyer(ap, of_find_node_by_path("/aliases"));
maybe?

Reviewed-by: Jiri Slaby <jirislaby@...nel.org>

thanks,
-- 
js
suse labs