Commit 7fbf6795 authored by Colin Foster's avatar Colin Foster Committed by Jakub Kicinski
Browse files

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



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: default avatarColin Foster <colin.foster@in-advantage.com>
Fixes: 1e1caa97 ("ocelot: Clean up stats update deferred work")
Fixes: a556c76a ("net: mscc: Add initial Ocelot switch support")
Reported-by: default avatarVladimir Oltean <vladimir.oltean@nxp.com>
Reviewed-by: default avatarVladimir Oltean <vladimir.oltean@nxp.com>
Link: https://lore.kernel.org/all/20220210150451.416845-2-colin.foster@in-advantage.com/


Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent c4416f5c

drivers/net/ethernet/mscc/ocelot.c

+7 −4
Original line number Diff line number Diff line
@@ -1745,12 +1745,11 @@ 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);
@@ -1769,8 +1768,6 @@ 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)
@@ -1779,7 +1776,9 @@ 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);
@@ -1789,12 +1788,16 @@ 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);