net: dsa: mv88e6xxx: Release mutex between each statistics read

The PTP code needs low latency access to the PTP hardware timestamps.
Reading all the statistics in one go adds a lot of latency to the PTP
code. So take and release the reg_lock mutex for each individual
statistics, allowing the PTP thread jump in between.

Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/dsa/mv88e6xxx/chip.c b/drivers/net/dsa/mv88e6xxx/chip.c
index af63710e93c1e9ce4c01063843544fd21390bb4d..bd5cb8a0330e7b3c2a756a3d165e21009bf3420a 100644 (file)
--- a/drivers/net/dsa/mv88e6xxx/chip.c
+++ b/drivers/net/dsa/mv88e6xxx/chip.c
@@ -714,9 +714,12 @@ static void mv88e6xxx_stats_get_stats(struct mv88e6xxx_chip *chip, int port,
        for (i = 0, j = 0; i < ARRAY_SIZE(mv88e6xxx_hw_stats); i++) {
                stat = &mv88e6xxx_hw_stats[i];
                if (stat->type & types) {
+                       mutex_lock(&chip->reg_lock);
                        data[j] = _mv88e6xxx_get_ethtool_stat(chip, stat, port,
                                                              bank1_select,
                                                              histogram);
+                       mutex_unlock(&chip->reg_lock);
+
                        j++;
                }
        }
@@ -764,14 +767,13 @@ static void mv88e6xxx_get_ethtool_stats(struct dsa_switch *ds, int port,
        mutex_lock(&chip->reg_lock);
 
        ret = mv88e6xxx_stats_snapshot(chip, port);
-       if (ret < 0) {
-               mutex_unlock(&chip->reg_lock);
+       mutex_unlock(&chip->reg_lock);
+
+       if (ret < 0)
                return;
-       }
 
        mv88e6xxx_get_stats(chip, port, data);
 
-       mutex_unlock(&chip->reg_lock);
 }
 
 static int mv88e6xxx_stats_set_histogram(struct mv88e6xxx_chip *chip)