From 485df8847a2c0ecf947a514f634b8180b725b827 Mon Sep 17 00:00:00 2001 From: Chengwen Feng Date: Fri, 13 May 2022 10:53:49 +0800 Subject: [PATCH] ethdev: clarify null location case in xstats get MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit When xstats location is null in rte_eth_xstats_get() the return value is not clearly specified. Some PMDs (eg. hns3/ipn3ke/mvpp2/axgbe) return zero while others return the required number of elements. In this patch, special parameter combinations are restricted: 1. highlight that xstats location may be null if and only if n is 0. 2. amend n parameter description to specify that if n is lower than the required number of elements, the function returns the required number of elements. 3. specify that if n is zero, the xstats must be NULL, the function returns the required number of elements (a duplicate which should help to not very attentive readers). Add sanity check for null xstats and non-zero n case on API level to make it unnecessary to care about it in drivers. Fixes: ce757f5c9a4d ("ethdev: new method to retrieve extended statistics") Cc: stable@dpdk.org Signed-off-by: Chengwen Feng Acked-by: Morten Brørup Reviewed-by: Andrew Rybchenko --- lib/ethdev/rte_ethdev.c | 4 +++- lib/ethdev/rte_ethdev.h | 6 +++++- 2 files changed, 8 insertions(+), 2 deletions(-) diff --git a/lib/ethdev/rte_ethdev.c b/lib/ethdev/rte_ethdev.c index 8520aec561..af55edb6b9 100644 --- a/lib/ethdev/rte_ethdev.c +++ b/lib/ethdev/rte_ethdev.c @@ -2973,6 +2973,8 @@ rte_eth_xstats_get(uint16_t port_id, struct rte_eth_xstat *xstats, int ret; RTE_ETH_VALID_PORTID_OR_ERR_RET(port_id, -ENODEV); + if (xstats == NULL && n > 0) + return -EINVAL; dev = &rte_eth_devices[port_id]; nb_rxqs = RTE_MIN(dev->data->nb_rx_queues, RTE_ETHDEV_QUEUE_STAT_CNTRS); @@ -2989,7 +2991,7 @@ rte_eth_xstats_get(uint16_t port_id, struct rte_eth_xstat *xstats, * xstats struct. */ xcount = (*dev->dev_ops->xstats_get)(dev, - xstats ? xstats + count : NULL, + (n > count) ? xstats + count : NULL, (n > count) ? n - count : 0); if (xcount < 0) diff --git a/lib/ethdev/rte_ethdev.h b/lib/ethdev/rte_ethdev.h index 04cff8ee10..04225bba4d 100644 --- a/lib/ethdev/rte_ethdev.h +++ b/lib/ethdev/rte_ethdev.h @@ -3174,9 +3174,13 @@ int rte_eth_xstats_get_names(uint16_t port_id, * @param xstats * A pointer to a table of structure of type *rte_eth_xstat* * to be filled with device statistics ids and values. - * This parameter can be set to NULL if n is 0. + * This parameter can be set to NULL if and only if n is 0. * @param n * The size of the xstats array (number of elements). + * If lower than the required number of elements, the function returns + * the required number of elements. + * If equal to zero, the xstats must be NULL, the function returns the + * required number of elements. * @return * - A positive value lower or equal to n: success. The return value * is the number of entries filled in the stats table. -- 2.39.5