Re: [dpdk-dev] [PATCH v3] bonding: fix the segfault caused by the race condition between master thread and eal-intr-thread

[Ferruh Yigit <ferruh.yigit@intel.com>]

On 9/4/2017 4:54 AM, Radu Nicolau wrote:
> Hi,
> 
> Wouldn't be possible to treat the section of code that segfaults as a 
> critical one, i.e. use the lock/unlock instead of triggering alarms?

Hi Sha,

Any update? Is this patch still valid?

Thanks,
ferruh

> 
> 
> On 7/26/2017 11:13 AM, zhangsha.zhang@huawei.com wrote:
>> From: Sha Zhang <zhangsha.zhang@huawei.com>
>>
>> Function slave_configure calls functions bond_ethdev_lsc_event_callback and
>> slave_eth_dev->dev_ops->link_update to fix updating slave link status.
>> But there is a low probability that process may be crashed if the master
>> thread, which create bonding-device, adds the active_slave_count of the
>> bond to nozero while the rx_ring or tx_ring of it haven't been created.
>>
>> This patch moves the functions bond_ethdev_lsc_event_callback and
>> slave_eth_dev->dev_ops->link_update to eal-intr-thread to aviod the
>> competition.
>>
>> Fixes: 210903803f6e ("net/bonding: fix updating slave link status")
>>
>> Signed-off-by: Sha Zhang <zhangsha.zhang@huawei.com>
>> ---
>>   drivers/net/bonding/rte_eth_bond_pmd.c | 58 +++++++++++++++++++++++++++++-----
>>   1 file changed, 50 insertions(+), 8 deletions(-)
>>
>> diff --git a/drivers/net/bonding/rte_eth_bond_pmd.c b/drivers/net/bonding/rte_eth_bond_pmd.c
>> index 383e27c..bc0ee7f 100644
>> --- a/drivers/net/bonding/rte_eth_bond_pmd.c
>> +++ b/drivers/net/bonding/rte_eth_bond_pmd.c
>> @@ -53,6 +53,7 @@
>>   
>>   #define REORDER_PERIOD_MS 10
>>   #define DEFAULT_POLLING_INTERVAL_10_MS (10)
>> +#define BOND_LSC_DELAY_TIME_US (10 * 1000)
>>   
>>   #define HASH_L4_PORTS(h) ((h)->src_port ^ (h)->dst_port)
>>   
>> @@ -1800,14 +1801,6 @@ struct bwg_slave {
>>   		}
>>   	}
>>   
>> -	/* If lsc interrupt is set, check initial slave's link status */
>> -	if (slave_eth_dev->data->dev_flags & RTE_ETH_DEV_INTR_LSC) {
>> -		slave_eth_dev->dev_ops->link_update(slave_eth_dev, 0);
>> -		bond_ethdev_lsc_event_callback(slave_eth_dev->data->port_id,
>> -			RTE_ETH_EVENT_INTR_LSC, &bonded_eth_dev->data->port_id,
>> -			NULL);
>> -	}
>> -
>>   	return 0;
>>   }
>>   
>> @@ -1878,6 +1871,51 @@ struct bwg_slave {
>>   static void
>>   bond_ethdev_promiscuous_enable(struct rte_eth_dev *eth_dev);
>>   
>> +static void
>> +bond_ethdev_slave_lsc_delay(void *cb_arg)
>> +{
>> +	struct rte_eth_dev *bonded_ethdev, *slave_dev;
>> +	struct bond_dev_private *internals;
>> +
>> +	/* Default value for polling slave found is true as we don't
>> +	 *  want todisable the polling thread if we cannot get the lock.
>> +	 */
>> +	int i = 0;
>> +
>> +	if (!cb_arg)
>> +		return;
>> +
>> +	bonded_ethdev = (struct rte_eth_dev *)cb_arg;
>> +	if (!bonded_ethdev->data->dev_started)
>> +		return;
>> +
>> +	internals = (struct bond_dev_private *)bonded_ethdev->data->dev_private;
>> +	if (!rte_spinlock_trylock(&internals->lock)) {
>> +		rte_eal_alarm_set(BOND_LSC_DELAY_TIME_US * 10,
>> +				  bond_ethdev_slave_lsc_delay,
>> +				  (void *)&rte_eth_devices[internals->port_id]);
>> +		return;
>> +	}
>> +
>> +	for (i = 0; i < internals->slave_count; i++) {
>> +		slave_dev = &(rte_eth_devices[internals->slaves[i].port_id]);
>> +		if (slave_dev->data->dev_conf.intr_conf.lsc != 0) {
>> +			if (slave_dev->dev_ops &&
>> +			    slave_dev->dev_ops->link_update)
>> +				slave_dev->dev_ops->link_update(slave_dev, 0);
>> +			bond_ethdev_lsc_event_callback(
>> +				internals->slaves[i].port_id,
>> +				RTE_ETH_EVENT_INTR_LSC,
>> +				&bonded_ethdev->data->port_id, NULL);
>> +		}
>> +	}
>> +	rte_spinlock_unlock(&internals->lock);
>> +	RTE_LOG(INFO, EAL,
>> +		"bond %s(%u): slave num %d, current active slave num %d\n",
>> +		bonded_ethdev->data->name, bonded_ethdev->data->port_id,
>> +		internals->slave_count, internals->active_slave_count);
>> +}
>> +
>>   static int
>>   bond_ethdev_start(struct rte_eth_dev *eth_dev)
>>   {
>> @@ -1953,6 +1991,10 @@ struct bwg_slave {
>>   		if (internals->slaves[i].link_status_poll_enabled)
>>   			internals->link_status_polling_enabled = 1;
>>   	}
>> +
>> +	rte_eal_alarm_set(BOND_LSC_DELAY_TIME_US, bond_ethdev_slave_lsc_delay,
>> +			  (void *)&rte_eth_devices[internals->port_id]);
>> +
>>   	/* start polling if needed */
>>   	if (internals->link_status_polling_enabled) {
>>   		rte_eal_alarm_set(
> 
>