netdev - Re: [PATCH] can: raw: raw_getsockopt(): reduce scope of err

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Date: Tue, 20 Feb 2024 17:27:05 +0900
From: Vincent Mailhol <vincent.mailhol@...il.com>
To: Marc Kleine-Budde <mkl@...gutronix.de>
Cc: Oliver Hartkopp <socketcan@...tkopp.net>, "David S. Miller" <davem@...emloft.net>, 
	Eric Dumazet <edumazet@...gle.com>, Jakub Kicinski <kuba@...nel.org>, Paolo Abeni <pabeni@...hat.com>, 
	linux-can@...r.kernel.org, netdev@...r.kernel.org, 
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] can: raw: raw_getsockopt(): reduce scope of err

On Tue. 20 Feb. 2024 at 17:16, Marc Kleine-Budde <mkl@...gutronix.de> wrote:
> Reduce the scope of the variable "err" to the individual cases. This
> is to avoid the mistake of setting "err" in the mistaken belief that
> it will be evaluated later.
>
> Signed-off-by: Marc Kleine-Budde <mkl@...gutronix.de>

One nitpick to remove a newline, but aside from that:

Reviewed-by: Vincent Mailhol <mailhol.vincent@...adoo.fr>

(as usual, I do not mind if the nitpick gets resolved while applying).

> ---
>  net/can/raw.c | 12 ++++++++----
>  1 file changed, 8 insertions(+), 4 deletions(-)
>
> diff --git a/net/can/raw.c b/net/can/raw.c
> index 897ffc17d850..2bb3eab98af0 100644
> --- a/net/can/raw.c
> +++ b/net/can/raw.c
> @@ -756,7 +756,6 @@ static int raw_getsockopt(struct socket *sock, int level, int optname,
>         struct raw_sock *ro = raw_sk(sk);
>         int len;
>         void *val;
> -       int err = 0;
>
>         if (level != SOL_CAN_RAW)
>                 return -EINVAL;
> @@ -766,7 +765,9 @@ static int raw_getsockopt(struct socket *sock, int level, int optname,
>                 return -EINVAL;
>
>         switch (optname) {
> -       case CAN_RAW_FILTER:
> +       case CAN_RAW_FILTER: {

Aesthetically speaking, I do not like turning the cases into compound
statement, but this removes a pitfall, so let go for it!

> +               int err = 0;
> +
>                 lock_sock(sk);
>                 if (ro->count > 0) {
>                         int fsize = ro->count * sizeof(struct can_filter);
> @@ -791,7 +792,7 @@ static int raw_getsockopt(struct socket *sock, int level, int optname,
>                 if (!err)
>                         err = put_user(len, optlen);
>                 return err;
> -
> +       }
>         case CAN_RAW_ERR_FILTER:
>                 if (len > sizeof(can_err_mask_t))
>                         len = sizeof(can_err_mask_t);
> @@ -822,7 +823,9 @@ static int raw_getsockopt(struct socket *sock, int level, int optname,
>                 val = &ro->xl_frames;
>                 break;
>
> -       case CAN_RAW_XL_VCID_OPTS:
> +       case CAN_RAW_XL_VCID_OPTS: {
> +               int err = 0;
> +
>                 /* user space buffer to small for VCID opts? */
>                 if (len < sizeof(ro->raw_vcid_opts)) {
>                         /* return -ERANGE and needed space in optlen */
> @@ -839,6 +842,7 @@ static int raw_getsockopt(struct socket *sock, int level, int optname,
>                         err = put_user(len, optlen);
>                 return err;
>
> +       }

Nitpick: to be aligned with the above, also remove the newline here
(same as above):

-
+       }

>         case CAN_RAW_JOIN_FILTERS:
>                 if (len > sizeof(int))
>                         len = sizeof(int);