Commit 2e642afb authored by Maxim Mikityanskiy's avatar Maxim Mikityanskiy Committed by Saeed Mahameed
Browse files

net/mlx5e: Disable softirq in mlx5e_activate_rq to avoid race condition 



When the driver activates the channels, it assumes NAPI isn't running
yet. mlx5e_activate_rq posts a NOP WQE to ICOSQ to trigger a hardware
interrupt and start NAPI, which will run mlx5e_alloc_rx_mpwqe and post
UMR WQEs to ICOSQ to be able to receive packets with striding RQ.

Unfortunately, a race condition is possible if NAPI is triggered by
something else (for example, TX) at a bad timing, before
mlx5e_activate_rq finishes. In this case, mlx5e_alloc_rx_mpwqe may post
UMR WQEs to ICOSQ, and with the bad timing, the wqe_info of the first
UMR may be overwritten by the wqe_info of the NOP posted by
mlx5e_activate_rq.

The consequence is that icosq->db.wqe_info[0].num_wqebbs will be changed
from MLX5E_UMR_WQEBBS to 1, disrupting the integrity of the array-based
linked list in wqe_info[]. mlx5e_poll_ico_cq will hang in an infinite
loop after processing wqe_info[0], because after the corruption, the
next item to be processed will be wqe_info[1], which is filled with
zeros, and `sqcc += wi->num_wqebbs` will never move further.

This commit fixes this race condition by using async_icosq to post the
NOP and trigger the interrupt. async_icosq is always protected with a
spinlock, eliminating the race condition.

Fixes: bc77b240 ("net/mlx5e: Add fragmented memory support for RX multi packet WQE")
Signed-off-by: default avatarMaxim Mikityanskiy <maximmi@nvidia.com>
Reported-by: default avatarKarsten Nielsen <karsten@foo-bar.dk>
Reviewed-by: default avatarTariq Toukan <tariqt@nvidia.com>
Reviewed-by: default avatarGal Pressman <gal@nvidia.com>
Signed-off-by: default avatarSaeed Mahameed <saeedm@nvidia.com>
parent 1f2856cd

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

+4 −0
Original line number Diff line number Diff line
@@ -764,6 +764,7 @@ struct mlx5e_rq { 
	u8                     wq_type;

	u32                    rqn;

	struct mlx5_core_dev  *mdev;

	struct mlx5e_channel  *channel;

	u32  umr_mkey;

	struct mlx5e_dma_info  wqe_overflow;
@@ -1076,6 +1077,9 @@ void mlx5e_close_cq(struct mlx5e_cq *cq); 
int mlx5e_open_locked(struct net_device *netdev);

int mlx5e_close_locked(struct net_device *netdev);



void mlx5e_trigger_napi_icosq(struct mlx5e_channel *c);

void mlx5e_trigger_napi_sched(struct napi_struct *napi);



int mlx5e_open_channels(struct mlx5e_priv *priv,

			struct mlx5e_channels *chs);

void mlx5e_close_channels(struct mlx5e_channels *chs);

drivers/net/ethernet/mellanox/mlx5/core/en/ptp.c

+1 −0
Original line number Diff line number Diff line
@@ -736,6 +736,7 @@ void mlx5e_ptp_activate_channel(struct mlx5e_ptp *c) 
	if (test_bit(MLX5E_PTP_STATE_RX, c->state)) {

		mlx5e_ptp_rx_set_fs(c->priv);

		mlx5e_activate_rq(&c->rq);

		mlx5e_trigger_napi_sched(&c->napi);

	}

}

drivers/net/ethernet/mellanox/mlx5/core/en/reporter_rx.c

+6 −0
Original line number Diff line number Diff line
@@ -123,6 +123,8 @@ static int mlx5e_rx_reporter_err_icosq_cqe_recover(void *ctx) 
		xskrq->stats->recover++;

	}



	mlx5e_trigger_napi_icosq(icosq->channel);



	mutex_unlock(&icosq->channel->icosq_recovery_lock);



	return 0;
@@ -166,6 +168,10 @@ static int mlx5e_rx_reporter_err_rq_cqe_recover(void *ctx) 
	clear_bit(MLX5E_RQ_STATE_RECOVERING, &rq->state);

	mlx5e_activate_rq(rq);

	rq->stats->recover++;

	if (rq->channel)

		mlx5e_trigger_napi_icosq(rq->channel);

	else

		mlx5e_trigger_napi_sched(rq->cq.napi);

	return 0;

out:

	clear_bit(MLX5E_RQ_STATE_RECOVERING, &rq->state);

drivers/net/ethernet/mellanox/mlx5/core/en/trap.c

+1 −0
Original line number Diff line number Diff line
@@ -179,6 +179,7 @@ static void mlx5e_activate_trap(struct mlx5e_trap *trap) 
{

	napi_enable(&trap->napi);

	mlx5e_activate_rq(&trap->rq);

	mlx5e_trigger_napi_sched(&trap->napi);

}



void mlx5e_deactivate_trap(struct mlx5e_priv *priv)

drivers/net/ethernet/mellanox/mlx5/core/en/xsk/pool.c

+1 −0
Original line number Diff line number Diff line
@@ -117,6 +117,7 @@ static int mlx5e_xsk_enable_locked(struct mlx5e_priv *priv, 
		goto err_remove_pool;



	mlx5e_activate_xsk(c);

	mlx5e_trigger_napi_icosq(c);



	/* Don't wait for WQEs, because the newer xdpsock sample doesn't provide

	 * any Fill Ring entries at the setup stage.