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From: "Wodkowski, PawelX" <pawelx.wodkowski@intel.com>
To: Neil Horman <nhorman@tuxdriver.com>
Cc: "dev@dpdk.org" <dev@dpdk.org>,
	"Jastrzebski, MichalX K" <michalx.k.jastrzebski@intel.com>
Subject: Re: [dpdk-dev] [PATCH 2/2] bond: add mode 4 support
Date: Thu, 18 Sep 2014 08:07:31 +0000
Message-ID: <F6F2A6264E145F47A18AB6DF8E87425D12B24CC2@IRSMSX102.ger.corp.intel.com> (raw)
In-Reply-To: <20140917151304.GD4213@localhost.localdomain>

> > +int
> > +bond_mode_8023ad_deactivate_slave(struct rte_eth_dev *bond_dev,
> > +		uint8_t slave_pos)
> > +{
> > +	struct bond_dev_private *internals = bond_dev->data->dev_private;
> > +	struct mode8023ad_data *data = &internals->mode4;
> > +	struct port *port;
> > +	uint8_t i;
> > +
> > +	bond_mode_8023ad_stop(bond_dev);
> > +
> > +	/* Exclude slave from transmit policy. If this slave is an aggregator
> > +	 * make all aggregated slaves unselected to force sellection logic
> > +	 * to select suitable aggregator for this port	 */
> > +	for (i = 0; i < internals->active_slave_count; i++) {
> > +		port = &data->port_list[slave_pos];
> > +		if (port->used_agregator_idx == slave_pos) {
> > +			port->selected = UNSELECTED;
> > +			port->actor_state &= ~(STATE_SYNCHRONIZATION |
> STATE_DISTRIBUTING |
> > +				STATE_COLLECTING);
> > +
> > +			/* Use default aggregator */
> > +			port->used_agregator_idx = i;
> > +		}
> > +	}
> > +
> > +	port = &data->port_list[slave_pos];
> > +	timer_cancel(&port->current_while_timer);
> > +	timer_cancel(&port->periodic_timer);
> > +	timer_cancel(&port->wait_while_timer);
> > +	timer_cancel(&port->tx_machine_timer);
> > +
> These all seem rather racy.  Alarm callbacks are executed with the alarm list
> locks not held.  So there is every possibility that you could execute these (or
> any timer_cancel calls in this PMD in parallel with the internal state machine
> timer callback, and leave either with a corrupted timer list (resulting from a
> double free between here, and the actual callback site),

I don't think so. Yes, callbacks are executed with  alarm list locks not held, but 
this is not the issue because access to list itself is guarded by lock and 
ap->executing variable. So list will not be trashed. Check source of 
eal_alarm_callback(), rte_eal_alarm_set() and rte_eal_alarm_cancel().

> or a timer that is
> actually still pending when a slave is removed.
> 
This is not the issue also, but problem might be similar. I assumed that alarms
are atomic but when I looked at rte alarms closer I saw a race condition
between and rte_eal_alarm_cancel() from  bond_mode_8023ad_stop()
and rte_eal_alarm_set() from state machines callback. This need to be 
reworked in some way.

  reply	other threads:[~2014-09-18  8:01 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-09-17 14:21 [dpdk-dev] [PATCH 0/2] " Pawel Wodkowski
2014-09-17 14:21 ` [dpdk-dev] [PATCH 1/2] bond: extract common code to separate functions Pawel Wodkowski
2014-09-17 14:51   ` Neil Horman
2014-09-17 14:21 ` [dpdk-dev] [PATCH 2/2] bond: add mode 4 support Pawel Wodkowski
2014-09-17 15:13   ` Neil Horman
2014-09-18  8:07     ` Wodkowski, PawelX [this message]
2014-09-18 16:02       ` Neil Horman
2014-09-19 12:47         ` Wodkowski, PawelX
2014-09-19 17:29           ` Neil Horman
2014-09-22  6:26             ` Wodkowski, PawelX
2014-09-22 10:24               ` Neil Horman
     [not found]                 ` <60ABE07DBB3A454EB7FAD707B4BB158213896977@IRSMSX109.ger.corp.intel.com>
2014-09-22 13:15                   ` Neil Horman

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