Hi Andrew,
Some comments below.
On Sat, Jul 24, 2021 at 03:33:13PM +0300, Andrew Rybchenko wrote:
> From: Ivan Ilchenko <ivan.ilche...@oktetlabs.ru>
>
> Document valid combinations of input arguments in accordance with
> current implementation in ethdev.
>
> Fixes: 79c913a42f0 ("ethdev: retrieve xstats by ID")
> Cc: sta...@dpdk.org
>
> Signed-off-by: Ivan Ilchenko <ivan.ilche...@oktetlabs.ru>
> Signed-off-by: Andrew Rybchenko <andrew.rybche...@oktetlabs.ru>
> Reviewed-by: Andy Moreton <amore...@xilinx.com>
> ---
> lib/ethdev/rte_ethdev.h | 32 +++++++++++++++++++-------------
> 1 file changed, 19 insertions(+), 13 deletions(-)
>
> diff --git a/lib/ethdev/rte_ethdev.h b/lib/ethdev/rte_ethdev.h
> index d2b27c351f..b14067fe7e 100644
> --- a/lib/ethdev/rte_ethdev.h
> +++ b/lib/ethdev/rte_ethdev.h
> @@ -2872,13 +2872,17 @@ int rte_eth_xstats_get(uint16_t port_id, struct
> rte_eth_xstat *xstats,
> * @param port_id
> * The port identifier of the Ethernet device.
> * @param xstats_names
> - * An rte_eth_xstat_name array of at least *size* elements to
> - * be filled. If set to NULL, the function returns the required number
> - * of elements.
> + * Array to be filled in with names of requested device statistics.
> + * Must not be NULL if @p ids are specified (not NULL).
> * @param ids
> - * IDs array given by app to retrieve specific statistics
> + * IDs array given by app to retrieve specific statistics. May be NULL to
> + * retrieve names of all available statistics or, if @p xstats_names is
> + * NULL as well, just a number of available statistics.
double spaces before "just"
"a number" -> "the number"?
> * @param size
> - * The size of the xstats_names array (number of elements).
> + * If @p ids is not NULL, number of elements in the array with requested
> IDs
> + * and number of elements in @p xstats_names to put names in. If @p ids is
> + * NULL, number of elements in @p xstats_names to put all available
> statistics
> + * names in.
Just a suggestion here, I feel the following description would be clearer:
Number of elements in @p xstats_names array (if not NULL) and
in @p ids array (if not NULL).
Shouldn't we say that it has to be 0 if both arrays are NULL?
Also, the order of arguments is not the same in comment and in
the function. I think it can make sense to align the comment
to the prototype.
> * @return
> * - A positive value lower or equal to size: success. The return value
> * is the number of entries filled in the stats table.
Not seen in the patch, but right after this line, there is:
* - A positive value higher than size: error, the given statistics table
* is too small. The return value corresponds to the size that should
* be given to succeed. The entries in the table are not valid and
* shall not be used by the caller.
I wonder if it shouldn't be slighly reworded to remove 'error'. After
all, passing NULL arrays (and size == 0) is a valid, so the return is
not an error.
> @@ -2886,7 +2890,7 @@ int rte_eth_xstats_get(uint16_t port_id, struct
> rte_eth_xstat *xstats,
> * is too small. The return value corresponds to the size that should
> * be given to succeed. The entries in the table are not valid and
> * shall not be used by the caller.
> - * - A negative value on error (invalid port id).
> + * - A negative value on error.
> */
> int
> rte_eth_xstats_get_names_by_id(uint16_t port_id,
> @@ -2899,14 +2903,16 @@ rte_eth_xstats_get_names_by_id(uint16_t port_id,
> * @param port_id
> * The port identifier of the Ethernet device.
> * @param ids
> - * A pointer to an ids array passed by application. This tells which
> - * statistics values function should retrieve. This parameter
> - * can be set to NULL if size is 0. In this case function will retrieve
> - * all available statistics.
> + * IDs array given by app to retrieve specific statistics. May be NULL to
> + * retrieve all available statistics or, if @p values is NULL as well,
> + * just a number of available statistics.
> * @param values
> - * A pointer to a table to be filled with device statistics values.
> + * Array to be filled in with requested device statistics.
> + * Must not be NULL if ids are specified (not NULL).
> * @param size
> - * The size of the ids array (number of elements).
> + * If @p ids is not NULL, number of elements in the array with requested
> IDs
> + * and number of elements in @p values to put statistics in. If @p ids is
> NULL,
> + * number of elements in @p values to put all available statistics in.
> * @return
> * - A positive value lower or equal to size: success. The return value
> * is the number of entries filled in the stats table.
> @@ -2914,7 +2920,7 @@ rte_eth_xstats_get_names_by_id(uint16_t port_id,
> * is too small. The return value corresponds to the size that should
> * be given to succeed. The entries in the table are not valid and
> * shall not be used by the caller.
> - * - A negative value on error (invalid port id).
> + * - A negative value on error.
> */
Some of the comments above also apply here.
> int rte_eth_xstats_get_by_id(uint16_t port_id, const uint64_t *ids,
> uint64_t *values, unsigned int size);
> --
> 2.30.2
>
