linux-kernel - Re: [PATCH] Bluetooth: Simplify / fix return values from tk

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Message-ID: <CAOxioNm6pu+WFwDS8oTcBiLaCjHH9QZx5R6rEjUtKPZjqN26+w@mail.gmail.com>
Date:   Mon, 6 Apr 2020 12:15:19 -0700
From:   Sonny Sasaka <sonnysasaka@...omium.org>
To:     Guenter Roeck <linux@...ck-us.net>
Cc:     Marcel Holtmann <marcel@...tmann.org>,
        Johan Hedberg <johan.hedberg@...il.com>,
        "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        BlueZ <linux-bluetooth@...r.kernel.org>,
        netdev <netdev@...r.kernel.org>,
        LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] Bluetooth: Simplify / fix return values from tk_request

Reviewed-by: Sonny Sasaka <sonnysasaka@...omium.org>

On Fri, Apr 3, 2020 at 8:02 AM Guenter Roeck <linux@...ck-us.net> wrote:
>
> Some static checker run by 0day reports a variableScope warning.
>
> net/bluetooth/smp.c:870:6: warning:
>         The scope of the variable 'err' can be reduced. [variableScope]
>
> There is no need for two separate variables holding return values.
> Stick with the existing variable. While at it, don't pre-initialize
> 'ret' because it is set in each code path.
>
> tk_request() is supposed to return a negative error code on errors,
> not a bluetooth return code. The calling code converts the return
> value to SMP_UNSPECIFIED if needed.
>
> Fixes: 92516cd97fd4 ("Bluetooth: Always request for user confirmation for Just Works")
> Cc: Sonny Sasaka <sonnysasaka@...omium.org>
> Signed-off-by: Guenter Roeck <linux@...ck-us.net>
> ---
>  net/bluetooth/smp.c | 9 ++++-----
>  1 file changed, 4 insertions(+), 5 deletions(-)
>
> diff --git a/net/bluetooth/smp.c b/net/bluetooth/smp.c
> index d0b695ee49f6..30e8626dd553 100644
> --- a/net/bluetooth/smp.c
> +++ b/net/bluetooth/smp.c
> @@ -854,8 +854,7 @@ static int tk_request(struct l2cap_conn *conn, u8 remote_oob, u8 auth,
>         struct l2cap_chan *chan = conn->smp;
>         struct smp_chan *smp = chan->data;
>         u32 passkey = 0;
> -       int ret = 0;
> -       int err;
> +       int ret;
>
>         /* Initialize key for JUST WORKS */
>         memset(smp->tk, 0, sizeof(smp->tk));
> @@ -887,12 +886,12 @@ static int tk_request(struct l2cap_conn *conn, u8 remote_oob, u8 auth,
>         /* If Just Works, Continue with Zero TK and ask user-space for
>          * confirmation */
>         if (smp->method == JUST_WORKS) {
> -               err = mgmt_user_confirm_request(hcon->hdev, &hcon->dst,
> +               ret = mgmt_user_confirm_request(hcon->hdev, &hcon->dst,
>                                                 hcon->type,
>                                                 hcon->dst_type,
>                                                 passkey, 1);
> -               if (err)
> -                       return SMP_UNSPECIFIED;
> +               if (ret)
> +                       return ret;
>                 set_bit(SMP_FLAG_WAIT_USER, &smp->flags);
>                 return 0;
>         }
> --
> 2.17.1
>