netdev - Re: Possible issue with Mellanox mlx4/port handling

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Message-ID: <5040AD6E.5070205@redhat.com>
Date:	Fri, 31 Aug 2012 09:26:22 -0300
From:	Marcelo Ricardo Leitner <mleitner@...hat.com>
To:	netdev@...r.kernel.org
CC:	dledford@...hat.com
Subject: Re: Possible issue with Mellanox mlx4/port handling

Fixed subject, sorry the confusion.

On 08/31/2012 09:25 AM, Marcelo Ricardo Leitner wrote:
> Hi,
>
> Commit
> http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=commitdiff;h=4c41b3673759d096106e68bce586f103c51d4119
> inserted changes like:
>
> @@ -361,7 +361,7 @@ static int add_promisc_qp(struct mlx4_dev *dev, u8
> port,
> int err;
> struct mlx4_priv *priv = mlx4_priv(dev);
>
> - s_steer = &mlx4_priv(dev)->steer[0];
> + s_steer = &mlx4_priv(dev)->steer[port - 1];
>
> mutex_lock(&priv->mcg_table.mutex);
>
> But I fear we missed one part of the deal. Concept patch:
>
> @@ -365,7 +365,7 @@ static int add_promisc_qp(struct mlx4_dev *dev, u8
> port,
>
> mutex_lock(&priv->mcg_table.mutex);
>
> - if (get_promisc_qp(dev, 0, steer, qpn)) {
> + if (get_promisc_qp(dev, port - 1, steer, qpn)) {
> err = 0; /* Noting to do, already exists */
> goto out_mutex;
> }
>
> Because:
>
> static int add_promisc_qp(struct mlx4_dev *dev, u8 port,
> enum mlx4_steer_type steer, u32 qpn)
> {
> ...
> A) s_steer = &mlx4_priv(dev)->steer[port - 1];
>
> mutex_lock(&priv->mcg_table.mutex);
>
> if (get_promisc_qp(dev, 0, steer, qpn)) {
> err = 0; /* Noting to do, already exists */
> goto out_mutex;
> }
> ...
> /* add the new qpn to list of promisc qps */
> C) list_add_tail(&pqp->list, &s_steer->promisc_qps[steer]);
> ...
> }
>
> static struct mlx4_promisc_qp *get_promisc_qp(struct mlx4_dev *dev, u8
> pf_num,
> enum mlx4_steer_type steer,
> u32 qpn)
> {
> B) struct mlx4_steer *s_steer = &mlx4_priv(dev)->steer[pf_num];
> struct mlx4_promisc_qp *pqp;
>
> list_for_each_entry(pqp, &s_steer->promisc_qps[steer], list) {
> if (pqp->qpn == qpn)
> return pqp;
> }
> /* not found */
> return NULL;
> }
>
> As far as I can understand, we are changing a list for a port and
> checking for duplicates on the other list. Points marked as A, B and C
> for highlighting. Am I missing something? What do you think?
>
> FWIW, this call get_promisc_qp(dev, 0, ...) happens in other places too.
>
> Thank you,
> Marcelo.

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