net: cadence: macb: Synchronize stats calculations

Stats calculations involve a RMW to add the stat update to the existing
value. This is currently not protected by any synchronization mechanism,
so data races are possible. Add a spinlock to protect the update. The
reader side could be protected using u64_stats, but we would still need
a spinlock for the update side anyway. And we always do an update
immediately before reading the stats anyway.

Fixes: 89e5785fc8a6 ("[PATCH] Atmel MACB ethernet driver")
Signed-off-by: Sean Anderson <sean.anderson@linux.dev>
Link: https://patch.msgid.link/20250220162950.95941-1-sean.anderson@linux.dev
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/net/ethernet/cadence/macb.h b/drivers/net/ethernet/cadence/macb.h
index 5740c98d8c9f03605533b9204ad8b72328974a58..2847278d9cd48e7ef3c62be696488ec54fbac697 100644 (file)
--- a/drivers/net/ethernet/cadence/macb.h
+++ b/drivers/net/ethernet/cadence/macb.h
@@ -1279,6 +1279,8 @@ struct macb {
        struct clk              *rx_clk;
        struct clk              *tsu_clk;
        struct net_device       *dev;
+       /* Protects hw_stats and ethtool_stats */
+       spinlock_t              stats_lock;
        union {
                struct macb_stats       macb;
                struct gem_stats        gem;

diff --git a/drivers/net/ethernet/cadence/macb_main.c b/drivers/net/ethernet/cadence/macb_main.c
index 48496209fb16445d15ffd2f18f8d5e61fd2e29c9..c1f57d96e63fc410942b69a2ef513f9e2adaa771 100644 (file)
--- a/drivers/net/ethernet/cadence/macb_main.c
+++ b/drivers/net/ethernet/cadence/macb_main.c
@@ -1978,10 +1978,12 @@ static irqreturn_t macb_interrupt(int irq, void *dev_id)
 
                if (status & MACB_BIT(ISR_ROVR)) {
                        /* We missed at least one packet */
+                       spin_lock(&bp->stats_lock);
                        if (macb_is_gem(bp))
                                bp->hw_stats.gem.rx_overruns++;
                        else
                                bp->hw_stats.macb.rx_overruns++;
+                       spin_unlock(&bp->stats_lock);
 
                        if (bp->caps & MACB_CAPS_ISR_CLEAR_ON_WRITE)
                                queue_writel(queue, ISR, MACB_BIT(ISR_ROVR));
@@ -3102,6 +3104,7 @@ static struct net_device_stats *gem_get_stats(struct macb *bp)
        if (!netif_running(bp->dev))
                return nstat;
 
+       spin_lock_irq(&bp->stats_lock);
        gem_update_stats(bp);
 
        nstat->rx_errors = (hwstat->rx_frame_check_sequence_errors +
@@ -3131,6 +3134,7 @@ static struct net_device_stats *gem_get_stats(struct macb *bp)
        nstat->tx_aborted_errors = hwstat->tx_excessive_collisions;
        nstat->tx_carrier_errors = hwstat->tx_carrier_sense_errors;
        nstat->tx_fifo_errors = hwstat->tx_underrun;
+       spin_unlock_irq(&bp->stats_lock);
 
        return nstat;
 }
@@ -3138,12 +3142,13 @@ static struct net_device_stats *gem_get_stats(struct macb *bp)
 static void gem_get_ethtool_stats(struct net_device *dev,
                                  struct ethtool_stats *stats, u64 *data)
 {
-       struct macb *bp;
+       struct macb *bp = netdev_priv(dev);
 
-       bp = netdev_priv(dev);
+       spin_lock_irq(&bp->stats_lock);
        gem_update_stats(bp);
        memcpy(data, &bp->ethtool_stats, sizeof(u64)
                        * (GEM_STATS_LEN + QUEUE_STATS_LEN * MACB_MAX_QUEUES));
+       spin_unlock_irq(&bp->stats_lock);
 }
 
 static int gem_get_sset_count(struct net_device *dev, int sset)
@@ -3193,6 +3198,7 @@ static struct net_device_stats *macb_get_stats(struct net_device *dev)
                return gem_get_stats(bp);
 
        /* read stats from hardware */
+       spin_lock_irq(&bp->stats_lock);
        macb_update_stats(bp);
 
        /* Convert HW stats into netdevice stats */
@@ -3226,6 +3232,7 @@ static struct net_device_stats *macb_get_stats(struct net_device *dev)
        nstat->tx_carrier_errors = hwstat->tx_carrier_errors;
        nstat->tx_fifo_errors = hwstat->tx_underruns;
        /* Don't know about heartbeat or window errors... */
+       spin_unlock_irq(&bp->stats_lock);
 
        return nstat;
 }
@@ -5097,6 +5104,7 @@ static int macb_probe(struct platform_device *pdev)
                }
        }
        spin_lock_init(&bp->lock);
+       spin_lock_init(&bp->stats_lock);
 
        /* setup capabilities */
        macb_configure_caps(bp, macb_config);