Re: [dpdk-dev] [PATCH] net/failsafe: fix Rx interrupt reinstallation

[Matan Azrad <matan@mellanox.com>]

Hi Gaetan

Agree, will send V2.

> -----Original Message-----
> From: Gaëtan Rivet [mailto:gaetan.rivet@6wind.com]
> Sent: Wednesday, February 14, 2018 3:52 PM
> To: Matan Azrad <matan@mellanox.com>
> Cc: dev@dpdk.org
> Subject: Re: [PATCH] net/failsafe: fix Rx interrupt reinstallation
> 
> Hi Matan,
> 
> On Tue, Feb 13, 2018 at 10:59:32PM +0000, Matan Azrad wrote:
> > Fail-safe dev_start() operation can be called by both the application
> > and the hot-plug alarm mechanism.
> >
> > The installation of Rx interrupt are triggered from dev_start() in any
> > time it is called while actually the Rx interrupt should be installed
> > only by the application calls.
> >
> > So, each plug-in event causes reinstallation which causes memory leak.
> >
> > Trigger the Rx interrupt installation only for application calls.
> >
> > Fixes: 9e0360aebf23 ("net/failsafe: register as Rx interrupt mode")
> >
> > Signed-off-by: Matan Azrad <matan@mellanox.com>
> > ---
> >  drivers/net/failsafe/failsafe_ops.c | 10 ++++++----
> >  1 file changed, 6 insertions(+), 4 deletions(-)
> >
> > diff --git a/drivers/net/failsafe/failsafe_ops.c
> > b/drivers/net/failsafe/failsafe_ops.c
> > index 057e435..bbbd335 100644
> > --- a/drivers/net/failsafe/failsafe_ops.c
> > +++ b/drivers/net/failsafe/failsafe_ops.c
> > @@ -181,10 +181,12 @@
> >  	int ret;
> >
> >  	fs_lock(dev, 0);
> > -	ret = failsafe_rx_intr_install(dev);
> > -	if (ret) {
> > -		fs_unlock(dev, 0);
> > -		return ret;
> > +	if (PRIV(dev)->alarm_lock == 0) {
> 
> I dislike having to rely on unrelated context of execution to decide a code-
> path.
> 
> I'd prefer to make interrupt installation dependent on the interrupt state
> instead.
> 
> I think it should be possible to forbid reinstallation within
> failsafe_rx_intr_install directly, e.g.
> 
> diff --git a/drivers/net/failsafe/failsafe_intr.c
> b/drivers/net/failsafe/failsafe_intr.c
> index f6ff04dc8..46c3aa5f2 100644
> --- a/drivers/net/failsafe/failsafe_intr.c
> +++ b/drivers/net/failsafe/failsafe_intr.c
> @@ -523,7 +523,8 @@ failsafe_rx_intr_install(struct rte_eth_dev *dev)
>         const struct rte_intr_conf *const intr_conf =
>                         &priv->dev->data->dev_conf.intr_conf;
> 
> -       if (intr_conf->rxq == 0)
> +       if (intr_conf->rxq == 0 ||
> +           dev->intr_handle != NULL)
>                 return 0;
>         if (fs_rx_intr_vec_install(priv) < 0)
>                 return -rte_errno;
> 
> This way the logic is self-dependent and the check limited to this component.
> 
> There might be better way to do this, it's only an example to explain my
> point.
> 
> > +		ret = failsafe_rx_intr_install(dev);
> > +		if (ret) {
> > +			fs_unlock(dev, 0);
> > +			return ret;
> > +		}
> >  	}
> >  	FOREACH_SUBDEV(sdev, i, dev) {
> >  		if (sdev->state != DEV_ACTIVE)
> > --
> > 1.9.5
> >
> 
> --
> Gaëtan Rivet
> 6WIND