ar71xx: allocate rx/tx descriptor/buffers in one chunk

Reduces false sharing due to cache aliases

Signed-off-by: Felix Fietkau <nbd@nbd.name>

diff --git a/target/linux/ar71xx/files/drivers/net/ethernet/atheros/ag71xx/ag71xx_main.c b/target/linux/ar71xx/files/drivers/net/ethernet/atheros/ag71xx/ag71xx_main.c
index 93f8c5305d1f988255ee1a5045c6123d18f1acd9..e8eb632c772094ad16c023d0b3e1649b1dd62cd5 100644 (file)
--- a/target/linux/ar71xx/files/drivers/net/ethernet/atheros/ag71xx/ag71xx_main.c
+++ b/target/linux/ar71xx/files/drivers/net/ethernet/atheros/ag71xx/ag71xx_main.c
@@ -90,41 +90,6 @@ static inline void ag71xx_dump_intr(struct ag71xx *ag, char *label, u32 intr)
                (intr & AG71XX_INT_RX_BE) ? "RXBE " : "");
 }
 
-static void ag71xx_ring_free(struct ag71xx_ring *ring)
-{
-       int ring_size = BIT(ring->order);
-       kfree(ring->buf);
-
-       if (ring->descs_cpu)
-               dma_free_coherent(NULL, ring_size * AG71XX_DESC_SIZE,
-                                 ring->descs_cpu, ring->descs_dma);
-}
-
-static int ag71xx_ring_alloc(struct ag71xx_ring *ring)
-{
-       int ring_size = BIT(ring->order);
-       int err;
-
-       ring->descs_cpu = dma_alloc_coherent(NULL, ring_size * AG71XX_DESC_SIZE,
-                                            &ring->descs_dma, GFP_ATOMIC);
-       if (!ring->descs_cpu) {
-               err = -ENOMEM;
-               goto err;
-       }
-
-
-       ring->buf = kzalloc(ring_size * sizeof(*ring->buf), GFP_KERNEL);
-       if (!ring->buf) {
-               err = -ENOMEM;
-               goto err;
-       }
-
-       return 0;
-
-err:
-       return err;
-}
-
 static void ag71xx_ring_tx_clean(struct ag71xx *ag)
 {
        struct ag71xx_ring *ring = &ag->tx_ring;
@@ -315,30 +280,56 @@ static int ag71xx_ring_rx_refill(struct ag71xx *ag)
 
 static int ag71xx_rings_init(struct ag71xx *ag)
 {
-       int ret;
+       struct ag71xx_ring *tx = &ag->tx_ring;
+       struct ag71xx_ring *rx = &ag->rx_ring;
+       int ring_size = BIT(tx->order) + BIT(rx->order);
+       int tx_size = BIT(tx->order);
+
+       tx->buf = kzalloc(ring_size * sizeof(*tx->buf), GFP_KERNEL);
+       if (!tx->buf)
+               return -ENOMEM;
+
+       tx->descs_cpu = dma_alloc_coherent(NULL, ring_size * AG71XX_DESC_SIZE,
+                                          &tx->descs_dma, GFP_ATOMIC);
+       if (!tx->descs_cpu) {
+               kfree(tx->buf);
+               tx->buf = NULL;
+               return -ENOMEM;
+       }
 
-       ret = ag71xx_ring_alloc(&ag->tx_ring);
-       if (ret)
-               return ret;
+       rx->buf = &tx->buf[BIT(tx->order)];
+       rx->descs_cpu = ((void *)tx->descs_cpu) + tx_size * AG71XX_DESC_SIZE;
+       rx->descs_dma = tx->descs_dma + tx_size * AG71XX_DESC_SIZE;
 
        ag71xx_ring_tx_init(ag);
+       return ag71xx_ring_rx_init(ag);
+}
 
-       ret = ag71xx_ring_alloc(&ag->rx_ring);
-       if (ret)
-               return ret;
+static void ag71xx_rings_free(struct ag71xx *ag)
+{
+       struct ag71xx_ring *tx = &ag->tx_ring;
+       struct ag71xx_ring *rx = &ag->rx_ring;
+       int ring_size = BIT(tx->order) + BIT(rx->order);
 
-       ret = ag71xx_ring_rx_init(ag);
-       return ret;
+       if (tx->descs_cpu)
+               dma_free_coherent(NULL, ring_size * AG71XX_DESC_SIZE,
+                                 tx->descs_cpu, tx->descs_dma);
+
+       kfree(tx->buf);
+
+       tx->descs_cpu = NULL;
+       rx->descs_cpu = NULL;
+       tx->buf = NULL;
+       rx->buf = NULL;
 }
 
 static void ag71xx_rings_cleanup(struct ag71xx *ag)
 {
        ag71xx_ring_rx_clean(ag);
-       ag71xx_ring_free(&ag->rx_ring);
-
        ag71xx_ring_tx_clean(ag);
+       ag71xx_rings_free(ag);
+
        netdev_reset_queue(ag->dev);
-       ag71xx_ring_free(&ag->tx_ring);
 }
 
 static unsigned char *ag71xx_speed_str(struct ag71xx *ag)