Re: [RFC bpf-next v2 03/11] xsk: Support XDP_TX_METADATA_LEN

From: Simon Horman <simon.horman@corigine.com>
To: Stanislav Fomichev <sdf@google.com>
Cc: bpf@vger.kernel.org, ast@kernel.org, daniel@iogearbox.net,
	andrii@kernel.org, martin.lau@linux.dev, song@kernel.org,
	yhs@fb.com, john.fastabend@gmail.com, kpsingh@kernel.org,
	haoluo@google.com, jolsa@kernel.org
Subject: Re: [RFC bpf-next v2 03/11] xsk: Support XDP_TX_METADATA_LEN
Date: Thu, 22 Jun 2023 17:26:27 +0200	[thread overview]
Message-ID: <ZJRoI2U1WD83yz/J@corigine.com> (raw)
In-Reply-To: <20230621170244.1283336-4-sdf@google.com>

On Wed, Jun 21, 2023 at 10:02:36AM -0700, Stanislav Fomichev wrote:

...

> @@ -1137,6 +1145,27 @@ static int xsk_setsockopt(struct socket *sock, int level, int optname,
>  		mutex_unlock(&xs->mutex);
>  		return err;
>  	}
> +	case XDP_TX_METADATA_LEN:
> +	{
> +		int val;
> +
> +		if (optlen < sizeof(val))
> +			return -EINVAL;
> +		if (copy_from_sockptr(&val, optval, sizeof(val)))
> +			return -EFAULT;
> +
> +		if (val >= 256)
> +			return -EINVAL;
> +
> +		mutex_lock(&xs->mutex);
> +		if (xs->state != XSK_READY) {
> +			mutex_unlock(&xs->mutex);
> +			return -EBUSY;
> +		}
> +		xs->tx_metadata_len = val;
> +		mutex_unlock(&xs->mutex);
> +		return err;

Hi Stan,

clang-16 complains that err is used uninitialised here.

 net/xdp/xsk.c:1167:10: warning: variable 'err' is uninitialized when used here [-Wuninitialized]
                 return err;
                        ^~~
 net/xdp/xsk.c:1065:9: note: initialize the variable 'err' to silence this warning
         int err;
                ^
                 = 0

> +	}
>  	default:
>  		break;
>  	}

...