MFC r312528:

Make draining a sendqueue more robust.

Add own state variable to track if a sendqueue is stopped or not.
This will prevent traffic from entering the sendqueue while it is
being destroyed.

Update drain function to wait for traffic to be transmitted before
returning when the link state is active.

Add extra checks in transmit path for stopped SQ's.

While at it:
- Use likely() for a mbuf pointer check.
- Remove redundant IFF_DRV_RUNNING check.

Sponsored by:		Mellanox Technologies

3 files changed, 56 insertions, 18 deletions

diff --git a/sys/dev/mlx5/mlx5_en/en.h b/sys/dev/mlx5/mlx5_en/en.h
index bbb71ca..0a927c6 100644
--- a/sys/dev/mlx5/mlx5_en/en.h
+++ b/sys/dev/mlx5/mlx5_en/en.h
@@ -507,10 +507,11 @@ struct mlx5e_sq {
 	u16	bf_offset;
 	u16	cev_counter;		/* completion event counter */
 	u16	cev_factor;		/* completion event factor */
-	u32	cev_next_state;		/* next completion event state */
+	u16	cev_next_state;		/* next completion event state */
 #define	MLX5E_CEV_STATE_INITIAL 0	/* timer not started */
 #define	MLX5E_CEV_STATE_SEND_NOPS 1	/* send NOPs */
 #define	MLX5E_CEV_STATE_HOLD_NOPS 2	/* don't send NOPs yet */
+	u16	stopped;		/* set if SQ is stopped */
 	struct callout cev_callout;
 	union {
 		u32	d32[2];
diff --git a/sys/dev/mlx5/mlx5_en/mlx5_en_main.c b/sys/dev/mlx5/mlx5_en/mlx5_en_main.c
index 727268b..5ba2f02 100644
--- a/sys/dev/mlx5/mlx5_en/mlx5_en_main.c
+++ b/sys/dev/mlx5/mlx5_en/mlx5_en_main.c
@@ -1233,8 +1233,25 @@ mlx5e_sq_cev_timeout(void *arg)
 void
 mlx5e_drain_sq(struct mlx5e_sq *sq)
 {
+	int error;
+
+	/*
+	 * Check if already stopped.
+	 *
+	 * NOTE: The "stopped" variable is only written when both the
+	 * priv's configuration lock and the SQ's lock is locked. It
+	 * can therefore safely be read when only one of the two locks
+	 * is locked. This function is always called when the priv's
+	 * configuration lock is locked.
+	 */
+	if (sq->stopped != 0)
+		return;
 
 	mtx_lock(&sq->lock);
+
+	/* don't put more packets into the SQ */
+	sq->stopped = 1;
+
 	/* teardown event factor timer, if any */
 	sq->cev_next_state = MLX5E_CEV_STATE_HOLD_NOPS;
 	callout_stop(&sq->cev_callout);
@@ -1246,14 +1263,29 @@ mlx5e_drain_sq(struct mlx5e_sq *sq)
 	/* make sure it is safe to free the callout */
 	callout_drain(&sq->cev_callout);
 
+	/* wait till SQ is empty or link is down */
+	mtx_lock(&sq->lock);
+	while (sq->cc != sq->pc &&
+	    (sq->priv->media_status_last & IFM_ACTIVE) != 0) {
+		mtx_unlock(&sq->lock);
+		msleep(1);
+		sq->cq.mcq.comp(&sq->cq.mcq);
+		mtx_lock(&sq->lock);
+	}
+	mtx_unlock(&sq->lock);
+
 	/* error out remaining requests */
-	mlx5e_modify_sq(sq, MLX5_SQC_STATE_RDY, MLX5_SQC_STATE_ERR);
+	error = mlx5e_modify_sq(sq, MLX5_SQC_STATE_RDY, MLX5_SQC_STATE_ERR);
+	if (error != 0) {
+		if_printf(sq->ifp,
+		    "mlx5e_modify_sq() from RDY to ERR failed: %d\n", error);
+	}
 
 	/* wait till SQ is empty */
 	mtx_lock(&sq->lock);
 	while (sq->cc != sq->pc) {
 		mtx_unlock(&sq->lock);
-		msleep(4);
+		msleep(1);
 		sq->cq.mcq.comp(&sq->cq.mcq);
 		mtx_lock(&sq->lock);
 	}
diff --git a/sys/dev/mlx5/mlx5_en/mlx5_en_tx.c b/sys/dev/mlx5/mlx5_en/mlx5_en_tx.c
index eae3d72..be82a7b 100644
--- a/sys/dev/mlx5/mlx5_en/mlx5_en_tx.c
+++ b/sys/dev/mlx5/mlx5_en/mlx5_en_tx.c
@@ -81,11 +81,15 @@ static struct mlx5e_sq *
 mlx5e_select_queue(struct ifnet *ifp, struct mbuf *mb)
 {
 	struct mlx5e_priv *priv = ifp->if_softc;
+	struct mlx5e_channel * volatile *ppch;
+	struct mlx5e_channel *pch;
 	u32 ch;
 	u32 tc;
 
+	ppch = priv->channel;
+
 	/* check if channels are successfully opened */
-	if (unlikely(priv->channel == NULL))
+	if (unlikely(ppch == NULL))
 		return (NULL);
 
 	/* obtain VLAN information if present */
@@ -123,11 +127,11 @@ mlx5e_select_queue(struct ifnet *ifp, struct mbuf *mb)
 #endif
 	}
 
-	/* check if channel is allocated */
-	if (unlikely(priv->channel[ch] == NULL))
-		return (NULL);
-
-	return (&priv->channel[ch]->sq[tc]);
+	/* check if channel is allocated and not stopped */
+	pch = ppch[ch];
+	if (likely(pch != NULL && pch->sq[tc].stopped == 0))
+		return (&pch->sq[tc]);
+	return (NULL);
 }
 
 static inline u16
@@ -445,18 +449,21 @@ mlx5e_xmit_locked(struct ifnet *ifp, struct mlx5e_sq *sq, struct mbuf *mb)
 	struct mbuf *next;
 	int err = 0;
 
-	if ((ifp->if_drv_flags & IFF_DRV_RUNNING) == 0) {
-		if (mb)
-			err = drbr_enqueue(ifp, sq->br, mb);
-		return (err);
-	}
-
-	if (mb != NULL)
+	if (likely(mb != NULL)) {
 		/*
 		 * If we can't insert mbuf into drbr, try to xmit anyway.
 		 * We keep the error we got so we could return that after xmit.
 		 */
 		err = drbr_enqueue(ifp, sq->br, mb);
+	}
+
+	/*
+	 * Check if the network interface is closed or if the SQ is
+	 * being stopped:
+	 */
+	if (unlikely((ifp->if_drv_flags & IFF_DRV_RUNNING) == 0 ||
+	    sq->stopped != 0))
+		return (err);
 
 	/* Process the queue */
 	while ((next = drbr_peek(ifp, sq->br)) != NULL) {
@@ -470,8 +477,6 @@ mlx5e_xmit_locked(struct ifnet *ifp, struct mlx5e_sq *sq, struct mbuf *mb)
 			break;
 		}
 		drbr_advance(ifp, sq->br);
-		if ((ifp->if_drv_flags & IFF_DRV_RUNNING) == 0)
-			break;
 	}
 	/* Check if we need to write the doorbell */
 	if (likely(sq->doorbell.d64 != 0)) {