[dpdk-dev] [PATCH v2 1/2] eventdev: add device stop flush callback
Jerin Jacob
jerin.jacob at caviumnetworks.com
Mon Mar 12 07:25:28 CET 2018
-----Original Message-----
> When an event device is stopped, it drains all event queues. These events
> may contain pointers, so to prevent memory leaks eventdev now supports a
> user-provided flush callback that is called during the queue drain process.
> This callback is stored in process memory, so the callback must be
> registered by any process that may call rte_event_dev_stop().
>
> This commit also clarifies the behavior of rte_event_dev_stop().
>
> This follows this mailing list discussion:
> http://dpdk.org/ml/archives/dev/2018-January/087484.html
>
> Signed-off-by: Gage Eads <gage.eads at intel.com>
> ---
> v2: allow a NULL callback pointer to unregister the callback
>
> lib/librte_eventdev/rte_eventdev.c | 17 +++++++++
> lib/librte_eventdev/rte_eventdev.h | 55 +++++++++++++++++++++++++++-
> lib/librte_eventdev/rte_eventdev_version.map | 6 +++
> 3 files changed, 76 insertions(+), 2 deletions(-)
>
> diff --git a/lib/librte_eventdev/rte_eventdev.c b/lib/librte_eventdev/rte_eventdev.c
> index 851a119..1aacb7b 100644
> --- a/lib/librte_eventdev/rte_eventdev.c
> +++ b/lib/librte_eventdev/rte_eventdev.c
> @@ -1123,6 +1123,23 @@ rte_event_dev_start(uint8_t dev_id)
> return 0;
> }
>
> +typedef void (*eventdev_stop_flush_t)(uint8_t dev_id, struct rte_event event,
> + void *arg);
> +/**< Callback function called during rte_event_dev_stop(), invoked once per
> + * flushed event.
> + */
> +
> #define RTE_EVENTDEV_NAME_MAX_LEN (64)
> /**< @internal Max length of name of event PMD */
>
> @@ -1176,6 +1194,11 @@ struct rte_eventdev {
> event_dequeue_burst_t dequeue_burst;
> /**< Pointer to PMD dequeue burst function. */
>
> + eventdev_stop_flush_t dev_stop_flush;
> + /**< Optional, user-provided event flush function */
> + void *dev_stop_flush_arg;
> + /**< User-provided argument for event flush function */
> +
I think, we can move this additions to the internal rte_eventdev_data structure. Reasons are
1) Changes to "struct rte_eventdev" would call for ABI change
2) We can keep "struct rte_eventdev" only for fast path functions,
slow path functions can have additional redirection.
> struct rte_eventdev_data *data;
> /**< Pointer to device data */
> const struct rte_eventdev_ops *dev_ops;
> @@ -1822,6 +1845,34 @@ rte_event_dev_xstats_reset(uint8_t dev_id,
> */
> int rte_event_dev_selftest(uint8_t dev_id);
>
> +/**
> + * Registers a callback function to be invoked during rte_event_dev_stop() for
> + * each flushed event. This function can be used to properly dispose of queued
> + * events, for example events containing memory pointers.
> + *
> + * The callback function is only registered for the calling process. The
> + * callback function must be registered in every process that can call
> + * rte_event_dev_stop().
> + *
> + * To unregister a callback, call this function with a NULL callback pointer.
> + *
> + * @param dev_id
> + * The identifier of the device.
> + * @param callback
> + * Callback function invoked once per flushed event.
> + * @param userdata
> + * Argument supplied to callback.
> + *
> + * @return
> + * - 0 on success.
> + * - -EINVAL if *dev_id* is invalid
> + *
> + * @see rte_event_dev_stop()
> + */
> +int
> +rte_event_dev_stop_flush_callback_register(uint8_t dev_id,
> + eventdev_stop_flush_t callback, void *userdata);
> +
IMO, It would be better if we place this function near to rte_event_dev_stop().
Other than above minor changes, It looks good to me.
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