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Commit 7b33aaea authored by Tariq Toukan's avatar Tariq Toukan Committed by Saeed Mahameed
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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,
("39e6c820 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: default avatarTariq Toukan <tariqt@mellanox.com>
Cc: Eric Dumazet <edumazet@google.com>
Signed-off-by: default avatarSaeed Mahameed <saeedm@mellanox.com>
parent 29c2849e

drivers/net/ethernet/mellanox/mlx5/core/en.h

+0 −5
Original line number Diff line number Diff line
@@ -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;

drivers/net/ethernet/mellanox/mlx5/core/en_main.c

+0 −1
Original line number Diff line number Diff line
@@ -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)

drivers/net/ethernet/mellanox/mlx5/core/en_txrx.c

+1 −9
Original line number Diff line number Diff line
@@ -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);

}