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Miller" , UNGLinuxDriver@microchip.com, Alexandre Belloni , Claudiu Manoil , Vladimir Oltean , Vladimir Oltean Subject: [PATCH v6 net-next 1/5] net: mscc: ocelot: fix mutex lock error during ethtool stats read Date: Wed, 9 Feb 2022 20:13:41 -0800 Message-Id: <20220210041345.321216-2-colin.foster@in-advantage.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220210041345.321216-1-colin.foster@in-advantage.com> References: <20220210041345.321216-1-colin.foster@in-advantage.com> Content-Transfer-Encoding: 8bit Content-Type: text/plain X-ClientProxiedBy: MW4PR04CA0084.namprd04.prod.outlook.com (2603:10b6:303:6b::29) To DM5PR1001MB2345.namprd10.prod.outlook.com (2603:10b6:4:2d::31) MIME-Version: 1.0 X-MS-PublicTrafficType: Email X-MS-Office365-Filtering-Correlation-Id: 4b184d77-46e9-4dcf-bdc1-08d9ec4bfbc6 X-MS-TrafficTypeDiagnostic: BN7PR10MB2564:EE_ X-Microsoft-Antispam-PRVS: X-MS-Oob-TLC-OOBClassifiers: OLM:4714; X-MS-Exchange-SenderADCheck: 1 X-MS-Exchange-AntiSpam-Relay: 0 X-Microsoft-Antispam: BCL:0; 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At the same time, a user might query the statistics. While writing to the buffer is mutex-locked, reading from the buffer wasn't. This could lead to buggy reads by ethtool. Signed-off-by: Colin Foster Fixes: a556c76adc052 ("net: mscc: Add initial Ocelot switch support") Reported-by: Vladimir Oltean --- drivers/net/ethernet/mscc/ocelot.c | 11 +++++++---- 1 file changed, 7 insertions(+), 4 deletions(-) diff --git a/drivers/net/ethernet/mscc/ocelot.c b/drivers/net/ethernet/mscc/ocelot.c index 455293aa6343..6933dff1dd37 100644 --- a/drivers/net/ethernet/mscc/ocelot.c +++ b/drivers/net/ethernet/mscc/ocelot.c @@ -1737,12 +1737,11 @@ void ocelot_get_strings(struct ocelot *ocelot, int port, u32 sset, u8 *data) } EXPORT_SYMBOL(ocelot_get_strings); +/* Caller must hold &ocelot->stats_lock */ static void ocelot_update_stats(struct ocelot *ocelot) { int i, j; - mutex_lock(&ocelot->stats_lock); - for (i = 0; i < ocelot->num_phys_ports; i++) { /* Configure the port to read the stats from */ ocelot_write(ocelot, SYS_STAT_CFG_STAT_VIEW(i), SYS_STAT_CFG); @@ -1761,8 +1760,6 @@ static void ocelot_update_stats(struct ocelot *ocelot) ~(u64)U32_MAX) + val; } } - - mutex_unlock(&ocelot->stats_lock); } static void ocelot_check_stats_work(struct work_struct *work) @@ -1771,7 +1768,9 @@ static void ocelot_check_stats_work(struct work_struct *work) struct ocelot *ocelot = container_of(del_work, struct ocelot, stats_work); + mutex_lock(&ocelot->stats_lock); ocelot_update_stats(ocelot); + mutex_unlock(&ocelot->stats_lock); queue_delayed_work(ocelot->stats_queue, &ocelot->stats_work, OCELOT_STATS_CHECK_DELAY); @@ -1781,12 +1780,16 @@ void ocelot_get_ethtool_stats(struct ocelot *ocelot, int port, u64 *data) { int i; + mutex_lock(&ocelot->stats_lock); + /* check and update now */ ocelot_update_stats(ocelot); /* Copy all counters */ for (i = 0; i < ocelot->num_stats; i++) *data++ = ocelot->stats[port * ocelot->num_stats + i]; + + mutex_unlock(&ocelot->stats_lock); } EXPORT_SYMBOL(ocelot_get_ethtool_stats); -- 2.25.1