Re: [dpdk-dev] [Suspected-Phishing][PATCH] net/vhost: fix redundant queue state event

[Noa Ezra <noae@mellanox.com>]

> -----Original Message-----
> From: Maxime Coquelin [mailto:maxime.coquelin@redhat.com]
> Sent: Wednesday, June 26, 2019 10:01 AM
> To: Noa Ezra <noae@mellanox.com>
> Cc: Matan Azrad <matan@mellanox.com>; dev@dpdk.org; stable@dpdk.org
> Subject: Re: [Suspected-Phishing][PATCH] net/vhost: fix redundant queue
> state event
> 
> 
> 
> On 6/26/19 8:37 AM, Noa Ezra wrote:
> > Hi,
> >
> >> -----Original Message-----
> >> From: Maxime Coquelin [mailto:maxime.coquelin@redhat.com]
> >> Sent: Tuesday, June 25, 2019 11:24 AM
> >> To: Noa Ezra <noae@mellanox.com>
> >> Cc: Matan Azrad <matan@mellanox.com>; dev@dpdk.org;
> stable@dpdk.org
> >> Subject: Re: [Suspected-Phishing][PATCH] net/vhost: fix redundant
> >> queue state event
> >>
> >>
> >>
> >> On 6/25/19 9:04 AM, Noa Ezra wrote:
> >>> Hi,
> >>> What do you think about this patch?
> >>>
> >>> Thanks,
> >>> Noa.
> >>>
> >>>> -----Original Message-----
> >>>> From: Noa Ezra [mailto:noae@mellanox.com]
> >>>> Sent: Wednesday, June 19, 2019 9:16 AM
> >>>> To: maxime.coquelin@redhat.com
> >>>> Cc: Matan Azrad <matan@mellanox.com>; dev@dpdk.org; Noa Ezra
> >>>> <noae@mellanox.com>; stable@dpdk.org
> >>>> Subject: [Suspected-Phishing][PATCH] net/vhost: fix redundant queue
> >>>> state event
> >>>>
> >>>> In some situations, when a virtual machine is starting,
> >>>> vring_state_changed can be called while there was no change in the
> >>>> queue state. This fix makes sure that there was really a change in
> >>>> the queue state before calling the callback for EVENT_QUEUE_STATE.
> >>>>
> >>>> Fixes: ee584e9710b9 ("vhost: add driver on top of the library")
> >>>> Cc: stable@dpdk.org
> >>>> Reviewed-by: Matan Azrad <matan@mellanox.com>
> >>>> ---
> >>>>    drivers/net/vhost/rte_eth_vhost.c | 4 ++++
> >>>>    1 file changed, 4 insertions(+)
> >>>>
> >>>> diff --git a/drivers/net/vhost/rte_eth_vhost.c
> >>>> b/drivers/net/vhost/rte_eth_vhost.c
> >>>> index cad1e5c..fbe7a37 100644
> >>>> --- a/drivers/net/vhost/rte_eth_vhost.c
> >>>> +++ b/drivers/net/vhost/rte_eth_vhost.c
> >>>> @@ -855,6 +855,10 @@ struct vhost_xstats_name_off {
> >>>>    	/* won't be NULL */
> >>>>    	state = vring_states[eth_dev->data->port_id];
> >>>>    	rte_spinlock_lock(&state->lock);
> >>>> +	if (state->cur[vring] == enable) {
> >>>> +		rte_spinlock_unlock(&state->lock);
> >>>> +		return 0;
> >>>> +	}
> >>>>
> >>>>    	state->cur[vring] = enable;
> >>>>    	state->max_vring = RTE_MAX(vring, state->max_vring);
> >>
> >> Maybe the application would want to be notified a new queue is
> >> available, even if it is disabled?
> >
> > Can you please look again? As I understand it, "enable" is the "new state"
> parameter (can be enable/disable).
> > In this fix I make sure that there was really a change in the state before
> calling EVENT_QUEUE_STATE (with no change in the state).
> 
> Ok, I get it.
> 
> Maybe we would want to update state->max_vring even if we don't sent the
> event?

Ok, so do you think we should move the check (if there was a change) to after we update the max_vring?

> Thanks,
> Maxime
> >>
> >>>> --
> >>>> 1.8.3.1
> >>>