Patch "i40e: Do not enable NAPI on q_vectors that have no rings" has been added to the 4.4-stable tree

This is a note to let you know that I've just added the patch titled

i40e: Do not enable NAPI on q_vectors that have no rings

to the 4.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
i40e-do-not-enable-napi-on-q_vectors-that-have-no-rings.patch
and it can be found in the queue-4.4 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Alexander Duyck <[email protected]>
Date: Fri, 24 Mar 2017 15:01:42 -0700
Subject: i40e: Do not enable NAPI on q_vectors that have no rings

From: Alexander Duyck <[email protected]>

[ Upstream commit 13a8cd191a2b470cfd435b3b57dbd21aa65ff78c ]

When testing the epoll w/ busy poll code I found that I could get into a state where the i40e driver had q_vectors w/ active NAPI that had no rings. This was resulting in a divide by zero error. To correct it I am updating the driver code so that we only support NAPI on q_vectors that have 1 or more rings allocated to them.

---
 drivers/net/ethernet/intel/i40e/i40e_main.c |   16 ++++++++++++----
 1 file changed, 12 insertions(+), 4 deletions(-)

@@ -4201,8 +4201,12 @@ static void i40e_napi_enable_all(struct
 	if (!vsi->netdev)
 		return;
 
-	for (q_idx = 0; q_idx < vsi->num_q_vectors; q_idx++)
-		napi_enable(&vsi->q_vectors[q_idx]->napi);
+	for (q_idx = 0; q_idx < vsi->num_q_vectors; q_idx++) {
+		struct i40e_q_vector *q_vector = vsi->q_vectors[q_idx];
+
+		if (q_vector->rx.ring || q_vector->tx.ring)
+			napi_enable(&q_vector->napi);
+	}
 }
 
 /**

@@ -4216,8 +4220,12 @@ static void i40e_napi_disable_all(struct
 	if (!vsi->netdev)
 		return;
 
-	for (q_idx = 0; q_idx < vsi->num_q_vectors; q_idx++)
-		napi_disable(&vsi->q_vectors[q_idx]->napi);
+	for (q_idx = 0; q_idx < vsi->num_q_vectors; q_idx++) {
+		struct i40e_q_vector *q_vector = vsi->q_vectors[q_idx];
+
+		if (q_vector->rx.ring || q_vector->tx.ring)
+			napi_disable(&q_vector->napi);
+	}
 }
 
 /**

Patches currently in stable-queue which might be from [email protected] are

queue-4.4/i40e-do-not-enable-napi-on-q_vectors-that-have-no-rings.patch queue-4.4/net-do-not-allow-negative-values-for-busy_read-and-busy_poll-sysctl-interfaces.patch