Re: [dpdk-dev] [PATCH v7 3/3] net/tap: allow secondary process to access primary device queues

[Raslan Darawsheh <rasland@mellanox.com>]

You right about that fixed in the new version

Kindest regards,
Raslan Darawsheh

> -----Original Message-----
> From: Ferruh Yigit <ferruh.yigit@intel.com>
> Sent: Wednesday, October 17, 2018 3:07 PM
> To: Raslan Darawsheh <rasland@mellanox.com>; keith.wiles@intel.com
> Cc: Thomas Monjalon <thomas@monjalon.net>; dev@dpdk.org; Shahaf
> Shuler <shahafs@mellanox.com>; Ori Kam <orika@mellanox.com>
> Subject: Re: [PATCH v7 3/3] net/tap: allow secondary process to access
> primary device queues
> 
> On 10/17/2018 9:56 AM, Raslan Darawsheh wrote:
> > @@ -2082,6 +2214,16 @@ rte_pmd_tap_probe(struct rte_vdev_device
> *dev)
> >  	TAP_LOG(NOTICE, "Initializing pmd_tap for %s as %s",
> >  		name, tap_name);
> >
> > +	/* Register IPC feed callback */
> > +	if (!tap_devices_count) {
> > +		ret = rte_mp_action_register(TAP_MP_KEY,
> tap_mp_sync_queues);
> > +		if (ret < 0) {
> > +			TAP_LOG(ERR, "%s: Failed to register IPC callback:
> %s",
> > +				tuntap_name, strerror(rte_errno));
> > +			goto leave;
> > +		}
> > +	}
> > +	tap_devices_count++;
> >  	ret = eth_dev_tap_create(dev, tap_name, remote_iface,
> &user_mac,
> >  		ETH_TUNTAP_TYPE_TAP);
> >
> > @@ -2089,6 +2231,9 @@ rte_pmd_tap_probe(struct rte_vdev_device
> *dev)
> >  	if (ret == -1) {
> >  		TAP_LOG(ERR, "Failed to create pmd for %s as %s",
> >  			name, tap_name);
> > +		if (!tap_devices_count)
> > +			rte_mp_action_unregister(TAP_MP_KEY);
> > +		tap_devices_count--;
> >  		tap_unit--;		/* Restore the unit number */
> >  	}
> >  	rte_kvargs_free(kvlist);
> Fail recovery part seems broken, it can be like [1] or [2], but both requires a
> new variable.
> I double checked the logic in prev version of the patch that uses EEXIST
> return values, that is also broken. Overall the challenge is in error recovery
> part we don't know if we enter there before or after increasing dev_count,
> that is why a local variable required.
> 
> If you can fix the error recovery path using EEXIST without needing a new
> variable, I think that is better, but if not I suggest following [2] since the logic
> of increase the dev_count after device successfully created makes sense to
> me, but both works.
> 
> Thanks,
> ferruh
> 
> 
> [1]
>          /* Register IPC feed callback */
>          if (!tap_devices_count) {
>                  ret = rte_mp_action_register(TAP_MP_KEY, tap_mp_sync_queues);
>                  if (ret < 0) {
>                          TAP_LOG(ERR, "%s: Failed to register IPC callback: %s",
>                                  tuntap_name, strerror(rte_errno));
>                          goto leave;
>                  }
>          }
>          tap_devices_count++;
>          tap_devices_count_increased = 1;
>          ret = eth_dev_tap_create(dev, tap_name, remote_iface, &user_mac,
>                  ETH_TUNTAP_TYPE_TAP);
> 
>  leave:
>          if (ret == -1) {
>                  TAP_LOG(ERR, "Failed to create pmd for %s as %s",
>                          name, tap_name);
>                  if (tap_devices_count_increased == 1) {
>                          if (tap_devices_count == 1)
>                                  rte_mp_action_unregister(TAP_MP_KEY);
>                          tap_devices_count--;
>                  }
>                  tap_unit--;             /* Restore the unit number */
>          }
>          rte_kvargs_free(kvlist);
> 
> 
> 
> [2]
> 
>          /* Register IPC feed callback */
>          if (!tap_devices_count) {
>                  ret = rte_mp_action_register(TAP_MP_KEY, tap_mp_sync_queues);
>                  if (ret < 0) {
>                          TAP_LOG(ERR, "%s: Failed to register IPC callback: %s",
>                                  tuntap_name, strerror(rte_errno));
>                          goto leave;
>                  }
>                  mp_action_registered = 1;
>          }
>          ret = eth_dev_tap_create(dev, tap_name, remote_iface, &user_mac,
>                  ETH_TUNTAP_TYPE_TAP);
> 
> 
>  leave:
>          if (ret == -1) {
>                  TAP_LOG(ERR, "Failed to create pmd for %s as %s",
>                          name, tap_name);
>                  if (mp_action_registered == 1)
>                          rte_mp_action_unregister(TAP_MP_KEY);
>                  tap_unit--;             /* Restore the unit number */
>          } else {
>                  tap_devices_count++;
>          }
>          rte_kvargs_free(kvlist);