[PATCH net 4/8] net: mscc: ocelot: turn stats_lock into a spinlock

Vladimir Oltean
2022-08-16T13:54:34Z

ocelot_get_stats64() currently runs unlocked and therefore may collide
with ocelot_port_update_stats() which indirectly accesses the same
counters. However, ocelot_get_stats64() runs in atomic context, and we
cannot simply take the sleepable ocelot->stats_lock mutex. We need to
convert it to an atomic spinlock first. Do that as a preparatory change.

Signed-off-by: Vladimir Oltean <vladimir.oltean@nxp.com>
---
drivers/net/dsa/ocelot/felix_vsc9959.c | 4 ++--
drivers/net/ethernet/mscc/ocelot.c | 11 +++++------
include/soc/mscc/ocelot.h | 2 +-
3 files changed, 8 insertions(+), 9 deletions(-)

diff --git a/drivers/net/dsa/ocelot/felix_vsc9959.c b/drivers/net/dsa/ocelot/felix_vsc9959.c
index e1ebe21cad00..46fd6cd0d8f3 100644
--- a/drivers/net/dsa/ocelot/felix_vsc9959.c
+++ b/drivers/net/dsa/ocelot/felix_vsc9959.c
@@ -2171,7 +2171,7 @@ static void vsc9959_psfp_sgi_table_del(struct ocelot *ocelot,
static void vsc9959_psfp_counters_get(struct ocelot *ocelot, u32 index,
struct felix_stream_filter_counters *counters)
{
- mutex_lock(&ocelot->stats_lock);
+ spin_lock(&ocelot->stats_lock);

ocelot_rmw(ocelot, SYS_STAT_CFG_STAT_VIEW(index),
SYS_STAT_CFG_STAT_VIEW_M,
@@ -2188,7 +2188,7 @@ static void vsc9959_psfp_counters_get(struct ocelot *ocelot, u32 index,
SYS_STAT_CFG_STAT_CLEAR_SHOT(0x10),
SYS_STAT_CFG);

- mutex_unlock(&ocelot->stats_lock);
+ spin_unlock(&ocelot->stats_lock);
}

static int vsc9959_psfp_filter_add(struct ocelot *ocelot, int port,
diff --git a/drivers/net/ethernet/mscc/ocelot.c b/drivers/net/ethernet/mscc/ocelot.c
index d4649e4ee0e7..c67f162f8ab5 100644
--- a/drivers/net/ethernet/mscc/ocelot.c
+++ b/drivers/net/ethernet/mscc/ocelot.c
@@ -1906,13 +1906,13 @@ static void ocelot_check_stats_work(struct work_struct *work)
stats_work);
int i, err;

- mutex_lock(&ocelot->stats_lock);
+ spin_lock(&ocelot->stats_lock);
for (i = 0; i < ocelot->num_phys_ports; i++) {
err = ocelot_port_update_stats(ocelot, i);
if (err)
break;
}
- mutex_unlock(&ocelot->stats_lock);
+ spin_unlock(&ocelot->stats_lock);

if (err)
dev_err(ocelot->dev, "Error %d updating ethtool stats\n", err);
@@ -1925,7 +1925,7 @@ void ocelot_get_ethtool_stats(struct ocelot *ocelot, int port, u64 *data)
{
int i, err;

- mutex_lock(&ocelot->stats_lock);
+ spin_lock(&ocelot->stats_lock);

/* check and update now */
err = ocelot_port_update_stats(ocelot, port);
@@ -1934,7 +1934,7 @@ void ocelot_get_ethtool_stats(struct ocelot *ocelot, int port, u64 *data)
for (i = 0; i < ocelot->num_stats; i++)
*data++ = ocelot->stats[port * ocelot->num_stats + i];

- mutex_unlock(&ocelot->stats_lock);
+ spin_unlock(&ocelot->stats_lock);

if (err)
dev_err(ocelot->dev, "Error %d updating ethtool stats\n", err);
@@ -3363,7 +3363,7 @@ int ocelot_init(struct ocelot *ocelot)
if (!ocelot->stats)
return -ENOMEM;

- mutex_init(&ocelot->stats_lock);
+ spin_lock_init(&ocelot->stats_lock);
mutex_init(&ocelot->ptp_lock);
mutex_init(&ocelot->mact_lock);
mutex_init(&ocelot->fwd_domain_lock);
@@ -3511,7 +3511,6 @@ void ocelot_deinit(struct ocelot *ocelot)
cancel_delayed_work(&ocelot->stats_work);
destroy_workqueue(ocelot->stats_queue);
destroy_workqueue(ocelot->owq);
- mutex_destroy(&ocelot->stats_lock);
}
EXPORT_SYMBOL(ocelot_deinit);

diff --git a/include/soc/mscc/ocelot.h b/include/soc/mscc/ocelot.h
index e7e5b06deb2d..72b9474391da 100644
--- a/include/soc/mscc/ocelot.h
+++ b/include/soc/mscc/ocelot.h
@@ -752,7 +752,7 @@ struct ocelot {
struct ocelot_psfp_list psfp;

/* Workqueue to check statistics for overflow with its lock */
- struct mutex stats_lock;
+ spinlock_t stats_lock;
u64 *stats;
struct delayed_work stats_work;
struct workqueue_struct *stats_queue;
--
2.34.1