Re: [dpdk-dev] [PATCH v4 2/2] ethdev: make rte_flow API thread safe

[Thomas Monjalon <thomas@monjalon.net>]

09/10/2020 03:17, Suanming Mou:
> --- a/doc/guides/prog_guide/rte_flow.rst
> +++ b/doc/guides/prog_guide/rte_flow.rst
> +If PMD interfaces do not support re-entrancy/multi-thread safety, rte_flow

"API" should be inserted here to make clear which layer we talk about.

> +level functions will do it by mutex per port. The application can test the

"do it" is too vague. I suggest "protect threads".

> +dev_flags with RTE_ETH_DEV_FLOW_OPS_THREAD_SAFE in struct rte_eth_dev_data

The application access it through dev_info.

> +to know if the rte_flow thread-safe works under rte_flow level or PMD level.

Again insert "API": rte_flow API level

This sentence can be confusing. Better to say explicitly that
if RTE_ETH_DEV_FLOW_OPS_THREAD_SAFE is set, it means the protection
at API level is disabled.

> +Please note that the mutex only protects rte_flow level functions, other
> +control path functions are not in scope.

Please find a complete rewording with sentences split after punctuation:

If PMD interfaces do not support re-entrancy/multi-thread safety,
the rte_flow API functions will protect threads by mutex per port.
The application can check whether ``RTE_ETH_DEV_FLOW_OPS_THREAD_SAFE``
is set in ``dev_flags``, meaning the PMD is thread-safe regarding rte_flow,
so the API level protection is disabled.
Please note that this API-level mutex protects only rte_flow functions,
other control path functions are not in scope.


[...]
> --- a/doc/guides/rel_notes/release_20_11.rst
> +++ b/doc/guides/rel_notes/release_20_11.rst
> @@ -109,6 +109,12 @@ New Features
>    * Extern objects and functions can be plugged into the pipeline.
>    * Transaction-oriented table updates.
>  
> +* **Added thread safe support to rte_flow functions.**
> +
> +  Added ``RTE_ETH_DEV_FLOW_OPS_THREAD_SAFE`` device flag to indicate
> +  if PMD support thread safe operations. If PMD doesn't set the flag,
> +  rte_flow level functions will protect the flow operations with mutex.
> +

Should be sorted before drivers with other ethdev features if any.

[...]
> --- a/lib/librte_ethdev/rte_ethdev.h
> +++ b/lib/librte_ethdev/rte_ethdev.h
> +/** Device PMD supports thread safety flow operation */

"Device" is useless
safety -> safe (adjective before "flow operation")

It becomes:
/** PMD supports thread-safe flow operations */

> +#define RTE_ETH_DEV_FLOW_OPS_THREAD_SAFE  0x0001

OK for the name of the flag.

[...]
> --- a/lib/librte_ethdev/rte_ethdev_core.h
> +++ b/lib/librte_ethdev/rte_ethdev_core.h
> @@ -180,6 +183,7 @@ struct rte_eth_dev_data {
>  			 *   Valid if RTE_ETH_DEV_REPRESENTOR in dev_flags.
>  			 */
>  
> +	pthread_mutex_t fts_mutex; /**< rte flow ops thread safety mutex. */

"ts" or "safety" is redundant for a mutex.
I suggest "flow_ops_mutex" as a name.