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

[Andrew Rybchenko <andrew.rybchenko@oktetlabs.ru>]

On 3/15/21 10:27 PM, Stephen Hemminger wrote:
> 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.
> 
> 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);	

Return value must be checked here. It may return ENOTSUP and
EINVAL. If it fails, IMHO we should do cleanup and return NULL.

> +	pthread_mutex_init(&eth_dev->data->flow_ops_mutex, &attr);
>  
>  unlock:
>  	rte_spinlock_unlock(&eth_dev_shared_data->ownership_lock);
> 

Please, fix notes from Thomas and above.

Overall these patches LGTM.

I think we should not introduce any flags that flow ops
are multi-process safe. Nobody prevents to call the API in
multi-process case and it must behave consistently.
The patch makes ethdev API safe and it is responsibility
of the driver care about final multi-process safety.