linux-kernel - Re: [net-next PATCH v3 3/9] octeontx2-pf: Create representor netdev

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Message-ID: <20240501180656.GX2575892@kernel.org>
Date: Wed, 1 May 2024 19:06:56 +0100
From: Simon Horman <horms@...nel.org>
To: Geetha sowjanya <gakula@...vell.com>
Cc: netdev@...r.kernel.org, linux-kernel@...r.kernel.org, kuba@...nel.org,
	davem@...emloft.net, pabeni@...hat.com, edumazet@...gle.com,
	sgoutham@...vell.com, sbhatta@...vell.com, hkelam@...vell.com,
	Dan Carpenter <dan.carpenter@...aro.org>
Subject: Re: [net-next PATCH v3 3/9] octeontx2-pf: Create representor netdev

+ Dan Carpenter

On Sun, Apr 28, 2024 at 04:23:06PM +0530, Geetha sowjanya wrote:
> Adds initial devlink support to set/get the switchdev mode.
> Representor netdevs are created for each rvu devices when
> the switch mode is set to 'switchdev'. These netdevs are
> be used to control and configure VFs.
> 
> Signed-off-by: Geetha sowjanya <gakula@...vell.com>

Hi Geetha,

Some minor feedback from my side.

..

> diff --git a/drivers/net/ethernet/marvell/octeontx2/nic/rep.c b/drivers/net/ethernet/marvell/octeontx2/nic/rep.c

..

> +int rvu_rep_create(struct otx2_nic *priv, struct netlink_ext_ack *extack)
> +{
> +	int rep_cnt = priv->rep_cnt;
> +	struct net_device *ndev;
> +	struct rep_dev *rep;
> +	int rep_id, err;
> +	u16 pcifunc;
> +
> +	priv->reps = devm_kcalloc(priv->dev, rep_cnt, sizeof(struct rep_dev), GFP_KERNEL);

It looks like the size argument should be sizeof(struct rep_dev *)
or sizeof(*priv->reps).

Flagged by Coccinelle.

Please consider limiting lines in Networking code to 80 columns wide
where it can be achieved without too much bother.

> +	if (!priv->reps)
> +		return -ENOMEM;
> +
> +	for (rep_id = 0; rep_id < rep_cnt; rep_id++) {
> +		ndev = alloc_etherdev(sizeof(*rep));
> +		if (!ndev) {
> +			NL_SET_ERR_MSG_FMT_MOD(extack, "PFVF representor:%d creation failed\n",
> +					       rep_id);
> +			err = -ENOMEM;
> +			goto exit;
> +		}
> +
> +		rep = netdev_priv(ndev);
> +		priv->reps[rep_id] = rep;
> +		rep->mdev = priv;
> +		rep->netdev = ndev;
> +		rep->rep_id = rep_id;
> +
> +		ndev->min_mtu = OTX2_MIN_MTU;
> +		ndev->max_mtu = priv->hw.max_mtu;
> +		pcifunc = priv->rep_pf_map[rep_id];
> +		rep->pcifunc = pcifunc;
> +
> +		snprintf(ndev->name, sizeof(ndev->name), "r%dp%d", rep_id,
> +			 rvu_get_pf(pcifunc));
> +
> +		eth_hw_addr_random(ndev);
> +		err = register_netdev(ndev);
> +		if (err) {
> +			NL_SET_ERR_MSG_MOD(extack, "PFVF reprentator registration failed\n");

I don't think the string passed to NL_SET_ERR_MSG_MOD needs a trailing '\n'.
I'm unsure if this also applies to NL_SET_ERR_MSG_FMT_MOD or not.

Flagged by Coccinelle.


The current ndev appears to be leaked here,
as it does not appear to be covered by the unwind loop below.

I think this can be resolved using:

			free_netdev(ndev);

> +			goto exit;
> +		}
> +	}
> +	err = rvu_rep_napi_init(priv, extack);
> +	if (err)
> +		goto exit;

Even with the above fixed, Smatch complains that:

../rep.c:180 rvu_rep_create() warn: 'ndev' from alloc_etherdev_mqs() not released on lines: 180.
../rep.c:180 rvu_rep_create() warn: 'ndev' from register_netdev() not released on lines: 180.

Where line 180 is the very last line of the funciton: return err;

I think this is triggered by the error handling above.
However, I also think it is a false positive.
I've CCed Dan Carpenter as I'd value a second opinion on this one.

> +
> +	return 0;
> +exit:
> +	while (--rep_id >= 0) {
> +		rep = priv->reps[rep_id];
> +		unregister_netdev(rep->netdev);
> +		free_netdev(rep->netdev);
> +	}
> +	return err;
> +}

..