netdev - [net V2 4/9] net/mlx5e: Fix usage of rcu-protected pointer

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Message-Id: <20200710023018.31905-5-saeedm@mellanox.com>
Date:   Thu,  9 Jul 2020 19:30:13 -0700
From:   Saeed Mahameed <saeedm@...lanox.com>
To:     "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>
Cc:     netdev@...r.kernel.org, Vlad Buslov <vladbu@...lanox.com>,
        Roi Dayan <roid@...lanox.com>,
        Saeed Mahameed <saeedm@...lanox.com>
Subject: [net V2 4/9] net/mlx5e: Fix usage of rcu-protected pointer

From: Vlad Buslov <vladbu@...lanox.com>

In mlx5e_configure_flower() flow pointer is protected by rcu read lock.
However, after cited commit the pointer is being used outside of rcu read
block. Extend the block to protect all pointer accesses.

Fixes: 553f9328385d ("net/mlx5e: Support tc block sharing for representors")
Signed-off-by: Vlad Buslov <vladbu@...lanox.com>
Reviewed-by: Roi Dayan <roid@...lanox.com>
Signed-off-by: Saeed Mahameed <saeedm@...lanox.com>
---
 drivers/net/ethernet/mellanox/mlx5/core/en_tc.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c b/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
index 75f169aef1cf..cc8412151ca0 100644
--- a/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
+++ b/drivers/net/ethernet/mellanox/mlx5/core/en_tc.c
@@ -4687,13 +4687,12 @@ int mlx5e_configure_flower(struct net_device *dev, struct mlx5e_priv *priv,
 
 	rcu_read_lock();
 	flow = rhashtable_lookup(tc_ht, &f->cookie, tc_ht_params);
-	rcu_read_unlock();
 	if (flow) {
 		/* Same flow rule offloaded to non-uplink representor sharing tc block,
 		 * just return 0.
 		 */
 		if (is_flow_rule_duplicate_allowed(dev, rpriv) && flow->orig_dev != dev)
-			goto out;
+			goto rcu_unlock;
 
 		NL_SET_ERR_MSG_MOD(extack,
 				   "flow cookie already exists, ignoring");
@@ -4701,8 +4700,12 @@ int mlx5e_configure_flower(struct net_device *dev, struct mlx5e_priv *priv,
 				 "flow cookie %lx already exists, ignoring\n",
 				 f->cookie);
 		err = -EEXIST;
-		goto out;
+		goto rcu_unlock;
 	}
+rcu_unlock:
+	rcu_read_unlock();
+	if (flow)
+		goto out;
 
 	trace_mlx5e_configure_flower(f);
 	err = mlx5e_tc_add_flow(priv, f, flags, dev, &flow);
-- 
2.26.2