[patch net] mlxsw: spectrum_router: Free LPM tree upon failure

[patch net] mlxsw: spectrum_router: Free LPM tree upon failure

[Jiri Pirko]

From: Ido Schimmel <idosch@mellanox.com>

When a new LPM tree is created, we try to replace the trees in the
existing virtual routers with it. If we fail, the tree needs to be
freed.

Currently, this does not happen in the unlikely case where we fail to
bind the tree to the first virtual router, since its reference count
never transitions from 1 to 0.

Fix that by taking a reference before binding the tree.

Fixes: fc922bb0dd94 ("mlxsw: spectrum_router: Use one LPM tree for all virtual routers")
Signed-off-by: Ido Schimmel <idosch@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
---
 .../net/ethernet/mellanox/mlxsw/spectrum_router.c    | 20 ++++++++++++++------
 1 file changed, 14 insertions(+), 6 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c b/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
index 434b3922b34f..6c0391c13fe0 100644
--- a/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
+++ b/drivers/net/ethernet/mellanox/mlxsw/spectrum_router.c
@@ -821,13 +821,18 @@ static int mlxsw_sp_vr_lpm_tree_replace(struct mlxsw_sp *mlxsw_sp,
 	struct mlxsw_sp_lpm_tree *old_tree = fib->lpm_tree;
 	int err;
 
-	err = mlxsw_sp_vr_lpm_tree_bind(mlxsw_sp, fib, new_tree->id);
-	if (err)
-		return err;
 	fib->lpm_tree = new_tree;
 	mlxsw_sp_lpm_tree_hold(new_tree);
+	err = mlxsw_sp_vr_lpm_tree_bind(mlxsw_sp, fib, new_tree->id);
+	if (err)
+		goto err_tree_bind;
 	mlxsw_sp_lpm_tree_put(mlxsw_sp, old_tree);
 	return 0;
+
+err_tree_bind:
+	mlxsw_sp_lpm_tree_put(mlxsw_sp, new_tree);
+	fib->lpm_tree = old_tree;
+	return err;
 }
 
 static int mlxsw_sp_vrs_lpm_tree_replace(struct mlxsw_sp *mlxsw_sp,
@@ -868,11 +873,14 @@ static int mlxsw_sp_vrs_lpm_tree_replace(struct mlxsw_sp *mlxsw_sp,
 	return err;
 
 no_replace:
-	err = mlxsw_sp_vr_lpm_tree_bind(mlxsw_sp, fib, new_tree->id);
-	if (err)
-		return err;
 	fib->lpm_tree = new_tree;
 	mlxsw_sp_lpm_tree_hold(new_tree);
+	err = mlxsw_sp_vr_lpm_tree_bind(mlxsw_sp, fib, new_tree->id);
+	if (err) {
+		mlxsw_sp_lpm_tree_put(mlxsw_sp, new_tree);
+		fib->lpm_tree = NULL;
+		return err;
+	}
 	return 0;
 }
 
-- 
2.14.3

Re: [patch net] mlxsw: spectrum_router: Free LPM tree upon failure

[David Miller]

From: Jiri Pirko <jiri@resnulli.us>
Date: Thu, 18 Jan 2018 15:42:10 +0100

> From: Ido Schimmel <idosch@mellanox.com>
> 
> When a new LPM tree is created, we try to replace the trees in the
> existing virtual routers with it. If we fail, the tree needs to be
> freed.
> 
> Currently, this does not happen in the unlikely case where we fail to
> bind the tree to the first virtual router, since its reference count
> never transitions from 1 to 0.
> 
> Fix that by taking a reference before binding the tree.
> 
> Fixes: fc922bb0dd94 ("mlxsw: spectrum_router: Use one LPM tree for all virtual routers")
> Signed-off-by: Ido Schimmel <idosch@mellanox.com>
> Signed-off-by: Jiri Pirko <jiri@mellanox.com>

Applied, thanks Jiri.