net/mlx4_en: Schedule napi when RX buffers allocation fails

[ Upstream commit 07841f9d94c11afe00c0498cf242edf4075729f4 ]

When system is out of memory, refilling of RX buffers fails while
the driver continue to pass the received packets to the kernel stack.
At some point, when all RX buffers deplete, driver may fall into a
sleep, and not recover when memory for new RX buffers is once again
availible. This is because hardware does not have valid descriptors,
so no interrupt will be generated for the driver to return to work
in napi context. Fix it by schedule the napi poll function from
stats_task delayed workqueue, as long as the allocations fail.

Signed-off-by: Ido Shamay <idos@mellanox.com>
Signed-off-by: Amir Vadai <amirv@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/net/ethernet/mellanox/mlx4/en_netdev.c b/drivers/net/ethernet/mellanox/mlx4/en_netdev.c
index 3485acf03014c7e4df64fa94a770fce00abe5a35..2f1324bed7b3e580a2cec503ae2193010e8cc1ea 100644 (file)
--- a/drivers/net/ethernet/mellanox/mlx4/en_netdev.c
+++ b/drivers/net/ethernet/mellanox/mlx4/en_netdev.c
@@ -1467,6 +1467,7 @@ static void mlx4_en_service_task(struct work_struct *work)
                if (mdev->dev->caps.flags2 & MLX4_DEV_CAP_FLAG2_TS)
                        mlx4_en_ptp_overflow_check(mdev);
 
+               mlx4_en_recover_from_oom(priv);
                queue_delayed_work(mdev->workqueue, &priv->service_task,
                                   SERVICE_TASK_DELAY);
        }

diff --git a/drivers/net/ethernet/mellanox/mlx4/en_rx.c b/drivers/net/ethernet/mellanox/mlx4/en_rx.c
index 698d60de1255269c11363c0196fd16800d5c4f13..05ec5e151dedf51b0cbbda38230ee763cdd67d77 100644 (file)
--- a/drivers/net/ethernet/mellanox/mlx4/en_rx.c
+++ b/drivers/net/ethernet/mellanox/mlx4/en_rx.c
@@ -244,6 +244,12 @@ static int mlx4_en_prepare_rx_desc(struct mlx4_en_priv *priv,
        return mlx4_en_alloc_frags(priv, rx_desc, frags, ring->page_alloc, gfp);
 }
 
+static inline bool mlx4_en_is_ring_empty(struct mlx4_en_rx_ring *ring)
+{
+       BUG_ON((u32)(ring->prod - ring->cons) > ring->actual_size);
+       return ring->prod == ring->cons;
+}
+
 static inline void mlx4_en_update_rx_prod_db(struct mlx4_en_rx_ring *ring)
 {
        *ring->wqres.db.db = cpu_to_be32(ring->prod & 0xffff);
@@ -315,8 +321,7 @@ static void mlx4_en_free_rx_buf(struct mlx4_en_priv *priv,
               ring->cons, ring->prod);
 
        /* Unmap and free Rx buffers */
-       BUG_ON((u32) (ring->prod - ring->cons) > ring->actual_size);
-       while (ring->cons != ring->prod) {
+       while (!mlx4_en_is_ring_empty(ring)) {
                index = ring->cons & ring->size_mask;
                en_dbg(DRV, priv, "Processing descriptor:%d\n", index);
                mlx4_en_free_rx_desc(priv, ring, index);
@@ -491,6 +496,23 @@ err_allocator:
        return err;
 }
 
+/* We recover from out of memory by scheduling our napi poll
+ * function (mlx4_en_process_cq), which tries to allocate
+ * all missing RX buffers (call to mlx4_en_refill_rx_buffers).
+ */
+void mlx4_en_recover_from_oom(struct mlx4_en_priv *priv)
+{
+       int ring;
+
+       if (!priv->port_up)
+               return;
+
+       for (ring = 0; ring < priv->rx_ring_num; ring++) {
+               if (mlx4_en_is_ring_empty(priv->rx_ring[ring]))
+                       napi_reschedule(&priv->rx_cq[ring]->napi);
+       }
+}
+
 void mlx4_en_destroy_rx_ring(struct mlx4_en_priv *priv,
                             struct mlx4_en_rx_ring **pring,
                             u32 size, u16 stride)

diff --git a/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h b/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h
index ebbe244e80dde55068d924905e08d1d631821811..8687c8d5422787893a8ccb5ea40bc3cac5cfdd02 100644 (file)
--- a/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h
+++ b/drivers/net/ethernet/mellanox/mlx4/mlx4_en.h
@@ -790,6 +790,7 @@ int mlx4_en_activate_tx_ring(struct mlx4_en_priv *priv,
 void mlx4_en_deactivate_tx_ring(struct mlx4_en_priv *priv,
                                struct mlx4_en_tx_ring *ring);
 void mlx4_en_set_num_rx_rings(struct mlx4_en_dev *mdev);
+void mlx4_en_recover_from_oom(struct mlx4_en_priv *priv);
 int mlx4_en_create_rx_ring(struct mlx4_en_priv *priv,
                           struct mlx4_en_rx_ring **pring,
                           u32 size, u16 stride, int node);