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Subject[PATCH 4.9 13/93] mlxsw: spectrum_router: Avoid potential packets loss
Date
4.9-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Ido Schimmel <idosch@mellanox.com>


[ 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")
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c | 30 ++++++++++++------
1 file changed, 20 insertions(+), 10 deletions(-)

--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
@@ -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,

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