linux-kernel - Re: [PATCH] i2c: amd_mp2: handle num is 0 input for i2c_amd

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Date:   Sat, 5 Sep 2020 14:33:47 +0200
From:   Elie Morisse <syniurge@...il.com>
To:     trix@...hat.com
Cc:     "Shah, Nehal-bakulchandra" <nehal-bakulchandra.shah@....com>,
        Shyam Sundar S K <shyam-sundar.s-k@....com>,
        natechancellor@...il.com, ndesaulniers@...gle.com,
        linux-i2c@...r.kernel.org, linux-kernel@...r.kernel.org,
        clang-built-linux@...glegroups.com
Subject: Re: [PATCH] i2c: amd_mp2: handle num is 0 input for i2c_amd_xfer

Acked-by: Elie Morisse <syniurge@...il.com>

Le ven. 4 sept. 2020 à 20:06, <trix@...hat.com> a écrit :
>
> From: Tom Rix <trix@...hat.com>
>
> clang static analyzer reports this problem
>
> i2c-amd-mp2-plat.c:174:9: warning: Branch condition evaluates
>   to a garbage value
>         return err ? err : num;
>                ^~~
>
> err is not initialized, it depends on the being set in the
> transfer loop which will not happen if num is 0.  Surveying
> other master_xfer() implementations show all handle a 0 num.
>
> Because returning 0 is expected, initialize err to 0.
>
> Signed-off-by: Tom Rix <trix@...hat.com>
> ---
>  drivers/i2c/busses/i2c-amd-mp2-plat.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/drivers/i2c/busses/i2c-amd-mp2-plat.c b/drivers/i2c/busses/i2c-amd-mp2-plat.c
> index 17df9e8845b6..506433bc0ff2 100644
> --- a/drivers/i2c/busses/i2c-amd-mp2-plat.c
> +++ b/drivers/i2c/busses/i2c-amd-mp2-plat.c
> @@ -155,7 +155,7 @@ static int i2c_amd_xfer(struct i2c_adapter *adap, struct i2c_msg *msgs, int num)
>         struct amd_i2c_dev *i2c_dev = i2c_get_adapdata(adap);
>         int i;
>         struct i2c_msg *pmsg;
> -       int err;
> +       int err = 0;
>
>         /* the adapter might have been deleted while waiting for the bus lock */
>         if (unlikely(!i2c_dev->common.mp2_dev))
> --
> 2.18.1
>