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Patch "mlxsw: spectrum_router: Avoid potential packets loss" has been added to the 4.9-stable tree

PATCH [email protected] 1 participant 1 message Mar 18, 2017

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

mlxsw: spectrum_router: Avoid potential packets loss

to the 4.9-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:
mlxsw-spectrum_router-avoid-potential-packets-loss.patch
and it can be found in the queue-4.9 subdirectory.

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

Quoted 1 line

From foo@baz Sat Mar 18 22:03:25 CST 2017

From: Ido Schimmel <[email protected]>
Date: Tue, 28 Feb 2017 08:55:40 +0100
Subject: mlxsw: spectrum_router: Avoid potential packets loss

From: Ido Schimmel <[email protected]>

[ Upstream commit f7df4923fa986247e93ec2cdff5ca168fff14dcf ]

When the structure of the LPM tree changes (f.e., due to the addition of a new prefix), we unbind the old tree and then bind the new one. This may result in temporary packet loss.

Instead, overwrite the old binding with the new one.

Fixes 6b75c4807db3 ("mlxsw: spectrum_router: Add virtual router management")
---
 drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c |   30 ++++++++++++------
 1 file changed, 20 insertions(+), 10 deletions(-)
drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c +20 -10
@@ -500,30 +500,40 @@ static int
 mlxsw_sp_vr_lpm_tree_check(struct mlxsw_sp *mlxsw_sp, struct mlxsw_sp_vr *vr,
 			   struct mlxsw_sp_prefix_usage *req_prefix_usage)
 {
-	struct mlxsw_sp_lpm_tree *lpm_tree;
+	struct mlxsw_sp_lpm_tree *lpm_tree = vr->lpm_tree;
+	struct mlxsw_sp_lpm_tree *new_tree;
+	int err;
 
-	if (mlxsw_sp_prefix_usage_eq(req_prefix_usage,
-				     &vr->lpm_tree->prefix_usage))
+	if (mlxsw_sp_prefix_usage_eq(req_prefix_usage, &lpm_tree->prefix_usage))
 		return 0;
 
-	lpm_tree = mlxsw_sp_lpm_tree_get(mlxsw_sp, req_prefix_usage,
+	new_tree = mlxsw_sp_lpm_tree_get(mlxsw_sp, req_prefix_usage,
 					 vr->proto, false);
-	if (IS_ERR(lpm_tree)) {
+	if (IS_ERR(new_tree)) {
 		/* We failed to get a tree according to the required
 		 * prefix usage. However, the current tree might be still good
 		 * for us if our requirement is subset of the prefixes used
 		 * in the tree.
 		 */
 		if (mlxsw_sp_prefix_usage_subset(req_prefix_usage,
-						 &vr->lpm_tree->prefix_usage))
+						 &lpm_tree->prefix_usage))
 			return 0;
-		return PTR_ERR(lpm_tree);
+		return PTR_ERR(new_tree);
 	}
 
-	mlxsw_sp_vr_lpm_tree_unbind(mlxsw_sp, vr);
-	mlxsw_sp_lpm_tree_put(mlxsw_sp, vr->lpm_tree);
+	/* Prevent packet loss by overwriting existing binding */
+	vr->lpm_tree = new_tree;
+	err = mlxsw_sp_vr_lpm_tree_bind(mlxsw_sp, vr);
+	if (err)
+		goto err_tree_bind;
+	mlxsw_sp_lpm_tree_put(mlxsw_sp, lpm_tree);
+
+	return 0;
+
+err_tree_bind:
 	vr->lpm_tree = lpm_tree;
-	return mlxsw_sp_vr_lpm_tree_bind(mlxsw_sp, vr);
+	mlxsw_sp_lpm_tree_put(mlxsw_sp, new_tree);
+	return err;
 }
 
 static struct mlxsw_sp_vr *mlxsw_sp_vr_get(struct mlxsw_sp *mlxsw_sp,

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

queue-4.9/mlxsw-spectrum_router-avoid-potential-packets-loss.patch