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Date: Mon, 14 Feb 2022 10:26:30 +0100 From: Greg Kroah-Hartman <gregkh@...uxfoundation.org> To: linux-kernel@...r.kernel.org Cc: Greg Kroah-Hartman <gregkh@...uxfoundation.org>, stable@...r.kernel.org, Colin Foster <colin.foster@...advantage.com>, Vladimir Oltean <vladimir.oltean@....com>, Jakub Kicinski <kuba@...nel.org>, Sasha Levin <sashal@...nel.org> Subject: [PATCH 5.15 132/172] net: mscc: ocelot: fix mutex lock error during ethtool stats read From: Colin Foster <colin.foster@...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@...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@....com> Reviewed-by: Vladimir Oltean <vladimir.oltean@....com> Link: https://lore.kernel.org/all/20220210150451.416845-2-colin.foster@in-advantage.com/ Signed-off-by: Jakub Kicinski <kuba@...nel.org> Signed-off-by: Sasha Levin <sashal@...nel.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 be2dd69bfee8b..6aad0953e8fe5 100644 --- a/drivers/net/ethernet/mscc/ocelot.c +++ b/drivers/net/ethernet/mscc/ocelot.c @@ -1215,12 +1215,11 @@ 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); @@ -1239,8 +1238,6 @@ 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) @@ -1249,7 +1246,9 @@ 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); @@ -1259,12 +1258,16 @@ 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); -- 2.34.1
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