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net: mscc: ocelot: fix mutex lock error during ethtool stats read

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[ 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-advantage.com/
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Colin Foster 2022-02-10 07:04:51 -08:00 committed by Greg Kroah-Hartman
parent 809f030745
commit 3a3c65c487
1 changed files with 7 additions and 4 deletions
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11
drivers/net/ethernet/mscc/ocelot.c
View File

@ -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);