Re: [dpdk-dev] [PATCH] net/mlx4: fix drop flow resources not freed

[Adrien Mazarguil <adrien.mazarguil@6wind.com>]

On Tue, Jan 30, 2018 at 05:41:07PM +0100, Adrien Mazarguil wrote:
> Hi Moti,
> 
> On Tue, Jan 30, 2018 at 05:54:00PM +0200, Moti Haimovsky wrote:
> > This patch fixes the drop-flow resources not being freed when the device
> > is closed.
> > Issue can be observed when running testpmd and adding the following rule
> > more than once:
> > "flow create 0 ingress pattern eth / end actions drop / end"
> > then either exiting testpmd using the "quit" command or by running the
> > command: "port stop all"
> > 
> > Fixes: d3a7e09234e4 ("net/mlx4: allocate drop flow resources on demand")
> > Cc: stable@dpdk.org
> > 
> > Signed-off-by: Moti Haimovsky <motih@mellanox.com>
> 
> Thanks for investigating this problem, however I do not think the proposed
> patch uses the right approach to address it, more below.
<snip>
> We need to find out why we do not end up with a number of mlx5_drop_put()
> calls matching that of mlx5_drop_get(). One is likely missing somewhere.
> I'll have a look as well.

After investigation, the following change in mlx4_flow_toggle() should
do the trick:

         if (flow->drop) {
 +               if (flow->ibv_flow)
 +                       return 0;
                 mlx4_drop_get(priv);

Without this, an already-enabled drop flow rule takes another reference when
re-enabled, hence the issue. I can send a fix tomorrow.

-- 
Adrien Mazarguil
6WIND