linux-kernel - [PATCH 5.9 041/133] net: openvswitch: silence suspicious RCU usage warning

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Date:   Mon,  9 Nov 2020 13:55:03 +0100
From:   Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:     linux-kernel@...r.kernel.org
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        stable@...r.kernel.org,
        syzbot+9a8f8bfcc56e8578016c@...kaller.appspotmail.com,
        Eelco Chaudron <echaudro@...hat.com>,
        Jakub Kicinski <kuba@...nel.org>
Subject: [PATCH 5.9 041/133] net: openvswitch: silence suspicious RCU usage warning

From: Eelco Chaudron <echaudro@...hat.com>

[ Upstream commit fea07a487c6dd422dc8837237c9d2bc7c33119af ]

Silence suspicious RCU usage warning in ovs_flow_tbl_masks_cache_resize()
by replacing rcu_dereference() with rcu_dereference_ovsl().

In addition, when creating a new datapath, make sure it's configured under
the ovs_lock.

Fixes: 9bf24f594c6a ("net: openvswitch: make masks cache size configurable")
Reported-by: syzbot+9a8f8bfcc56e8578016c@...kaller.appspotmail.com
Signed-off-by: Eelco Chaudron <echaudro@...hat.com>
Link: https://lore.kernel.org/r/160439190002.56943.1418882726496275961.stgit@ebuild
Signed-off-by: Jakub Kicinski <kuba@...nel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
---
 net/openvswitch/datapath.c   |   14 +++++++-------
 net/openvswitch/flow_table.c |    2 +-
 2 files changed, 8 insertions(+), 8 deletions(-)

--- a/net/openvswitch/datapath.c
+++ b/net/openvswitch/datapath.c
@@ -1699,13 +1699,13 @@ static int ovs_dp_cmd_new(struct sk_buff
 	parms.port_no = OVSP_LOCAL;
 	parms.upcall_portids = a[OVS_DP_ATTR_UPCALL_PID];
 
-	err = ovs_dp_change(dp, a);
-	if (err)
-		goto err_destroy_meters;
-
 	/* So far only local changes have been made, now need the lock. */
 	ovs_lock();
 
+	err = ovs_dp_change(dp, a);
+	if (err)
+		goto err_unlock_and_destroy_meters;
+
 	vport = new_vport(&parms);
 	if (IS_ERR(vport)) {
 		err = PTR_ERR(vport);
@@ -1721,8 +1721,7 @@ static int ovs_dp_cmd_new(struct sk_buff
 				ovs_dp_reset_user_features(skb, info);
 		}
 
-		ovs_unlock();
-		goto err_destroy_meters;
+		goto err_unlock_and_destroy_meters;
 	}
 
 	err = ovs_dp_cmd_fill_info(dp, reply, info->snd_portid,
@@ -1737,7 +1736,8 @@ static int ovs_dp_cmd_new(struct sk_buff
 	ovs_notify(&dp_datapath_genl_family, reply, info);
 	return 0;
 
-err_destroy_meters:
+err_unlock_and_destroy_meters:
+	ovs_unlock();
 	ovs_meters_exit(dp);
 err_destroy_ports:
 	kfree(dp->ports);
--- a/net/openvswitch/flow_table.c
+++ b/net/openvswitch/flow_table.c
@@ -387,7 +387,7 @@ static struct mask_cache *tbl_mask_cache
 }
 int ovs_flow_tbl_masks_cache_resize(struct flow_table *table, u32 size)
 {
-	struct mask_cache *mc = rcu_dereference(table->mask_cache);
+	struct mask_cache *mc = rcu_dereference_ovsl(table->mask_cache);
 	struct mask_cache *new;
 
 	if (size == mc->cache_size)