net/mlx5e: Use kernel's mechanism to avoid missing NAPIs

We used a channel state bit MLX5E_CHANNEL_NAPI_SCHED to make
sure no NAPI is missed when a channel's napi_schedule() is called
for completion events of the different channel's resources/rings
while NAPI is currently running.
Now, as similar mechanism is implemented in kernel,
("39e6c8208d7b net: solve a NAPI race"),
we obsolete our own implementation and rely on the return value
of napi_complete_done().

This patch removes a redundant overhead of atomic bit operations.

Signed-off-by: Tariq Toukan <tariqt@mellanox.com>
Cc: Eric Dumazet <edumazet@google.com>
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en.h b/drivers/net/ethernet/mellanox/mlx5/core/en.h
index 9c0c07f..7c046ae 100644 (file)
--- a/drivers/net/ethernet/mellanox/mlx5/core/en.h
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en.h
@@ -570,10 +570,6 @@ struct mlx5e_rq {
        struct mlx5_core_mkey  umr_mkey;
 } ____cacheline_aligned_in_smp;
 
-enum channel_flags {
-       MLX5E_CHANNEL_NAPI_SCHED = 1,
-};
-
 struct mlx5e_channel {
        /* data path */
        struct mlx5e_rq            rq;
@@ -585,7 +581,6 @@ struct mlx5e_channel {
        struct net_device         *netdev;
        __be32                     mkey_be;
        u8                         num_tc;
-       unsigned long              flags;
 
        /* control */
        struct mlx5e_priv         *priv;

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
index 2da2ea2..b2f689e 100644 (file)
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_main.c
@@ -3697,7 +3697,6 @@ static int mlx5e_xdp_set(struct net_device *netdev, struct bpf_prog *prog)
 
                set_bit(MLX5E_RQ_STATE_ENABLED, &c->rq.state);
                /* napi_schedule in case we have missed anything */
-               set_bit(MLX5E_CHANNEL_NAPI_SCHED, &c->flags);
                napi_schedule(&c->napi);
 
                if (old_prog)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_txrx.c b/drivers/net/ethernet/mellanox/mlx5/core/en_txrx.c
index 439ba1f..92d9aa1 100644 (file)
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_txrx.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_txrx.c
@@ -40,8 +40,6 @@ int mlx5e_napi_poll(struct napi_struct *napi, int budget)
        int work_done;
        int i;
 
-       clear_bit(MLX5E_CHANNEL_NAPI_SCHED, &c->flags);
-
        for (i = 0; i < c->num_tc; i++)
                busy |= mlx5e_poll_tx_cq(&c->sq[i].cq, budget);
 
@@ -56,13 +54,8 @@ int mlx5e_napi_poll(struct napi_struct *napi, int budget)
        if (busy)
                return budget;
 
-       napi_complete_done(napi, work_done);
-
-       /* avoid losing completion event during/after polling cqs */
-       if (test_bit(MLX5E_CHANNEL_NAPI_SCHED, &c->flags)) {
-               napi_schedule(napi);
+       if (unlikely(!napi_complete_done(napi, work_done)))
                return work_done;
-       }
 
        for (i = 0; i < c->num_tc; i++)
                mlx5e_cq_arm(&c->sq[i].cq);
@@ -81,7 +74,6 @@ void mlx5e_completion_event(struct mlx5_core_cq *mcq)
        struct mlx5e_cq *cq = container_of(mcq, struct mlx5e_cq, mcq);
 
        cq->event_ctr++;
-       set_bit(MLX5E_CHANNEL_NAPI_SCHED, &cq->channel->flags);
        napi_schedule(cq->napi);
 }