Re: [dpdk-dev] [PATCH 1/2] ethdev: make flow API primary/secondary process safe

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

On 3/16/2021 11:48 PM, Suanming Mou wrote:
> Hi Stephen,
> 
>> -----Original Message-----
>> From: Stephen Hemminger <stephen@networkplumber.org>
>> Sent: Tuesday, March 16, 2021 3:27 AM
>> To: dev@dpdk.org
>> Cc: Stephen Hemminger <stephen@networkplumber.org>; Suanming Mou
>> <suanmingm@nvidia.com>
>> Subject: [PATCH 1/2] ethdev: make flow API primary/secondary process safe
>>
>> Posix mutex are not by default safe for protecting for usage from multiple
>> processes. The flow ops mutex could be used by both primary and secondary
>> processes.
> 
> Process safe is something more widely scope. I assume it should be another feature but not a bugfix for thread-safe?
> And the fag RTE_ETH_DEV_FLOW_OPS_THREAD_SAFE we have added is just thread safe.
> 

Hi Suanming,

I think 'RTE_ETH_DEV_FLOW_OPS_THREAD_SAFE' flag and what this patch address are 
different issues.

'RTE_ETH_DEV_FLOW_OPS_THREAD_SAFE' is to add/remove synchronization support for 
flow APIs, that is for thread safety as flag name suggests.

This patch is to solve the problem for multi process, where commit log describes 
as posix mutex is not safe for multiple process.


Stephen,
Are you aware of any downside setting 'PTHREAD_PROCESS_SHARED' attribute to the 
mutex? Any possible performance implications?

Ori,
Since mlx is heavily using the flow API, is it possible to test this patch? If 
there is no negative impact, I think we can get this patch, what do you think?

>>
>> Bugzilla ID: 662
>> Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
>> Fixes: 80d1a9aff7f6 ("ethdev: make flow API thread safe")
>> Cc: suanmingm@nvidia.com
>> ---
>>   lib/librte_ethdev/rte_ethdev.c | 6 +++++-
>>   1 file changed, 5 insertions(+), 1 deletion(-)
>>
>> diff --git a/lib/librte_ethdev/rte_ethdev.c b/lib/librte_ethdev/rte_ethdev.c index
>> 6f514c388b4e..d1024df408a5 100644
>> --- a/lib/librte_ethdev/rte_ethdev.c
>> +++ b/lib/librte_ethdev/rte_ethdev.c
>> @@ -470,6 +470,7 @@ rte_eth_dev_allocate(const char *name)  {
>>   	uint16_t port_id;
>>   	struct rte_eth_dev *eth_dev = NULL;
>> +	pthread_mutexattr_t attr;
>>   	size_t name_len;
>>
>>   	name_len = strnlen(name, RTE_ETH_NAME_MAX_LEN); @@ -506,7
>> +507,10 @@ rte_eth_dev_allocate(const char *name)
>>   	strlcpy(eth_dev->data->name, name, sizeof(eth_dev->data->name));
>>   	eth_dev->data->port_id = port_id;
>>   	eth_dev->data->mtu = RTE_ETHER_MTU;
>> -	pthread_mutex_init(&eth_dev->data->flow_ops_mutex, NULL);
>> +
>> +	pthread_mutexattr_init(&attr);
>> +	pthread_mutexattr_setpshared(&attr, PTHREAD_PROCESS_SHARED);
>>
>> +	pthread_mutex_init(&eth_dev->data->flow_ops_mutex, &attr);
>>
>>   unlock:
>>   	rte_spinlock_unlock(&eth_dev_shared_data->ownership_lock);
>> --
>> 2.30.2
>