From: Colin Foster colin.foster@in-advantage.com
[ Upstream commit 7fbf6795d127a3b1bb39b0e42579904cf6db1624 ]
An ongoing workqueue populates the stats buffer. 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.
This patch fixes the former blamed commit, but the bug was introduced in the latter.
Signed-off-by: Colin Foster colin.foster@in-advantage.com Fixes: 1e1caa9735f90 ("ocelot: Clean up stats update deferred work") Fixes: a556c76adc052 ("net: mscc: Add initial Ocelot switch support") Reported-by: Vladimir Oltean vladimir.oltean@nxp.com Reviewed-by: Vladimir Oltean vladimir.oltean@nxp.com Link: https://lore.kernel.org/all/20220210150451.416845-2-colin.foster@in-advantag... Signed-off-by: Jakub Kicinski kuba@kernel.org Signed-off-by: Sasha Levin sashal@kernel.org --- 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 52401915828a1..a06466ecca12a 100644 --- a/drivers/net/ethernet/mscc/ocelot.c +++ b/drivers/net/ethernet/mscc/ocelot.c @@ -848,12 +848,11 @@ 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); @@ -872,8 +871,6 @@ 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) @@ -882,7 +879,9 @@ 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); @@ -892,12 +891,16 @@ 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);