openvswitch: drop unneeded BUG_ON() in ovs_flow_cmd_build_info()

BugLink: https://bugs.launchpad.net/bugs/1855313

[ Upstream commit 8ffeb03f ]

All the callers of ovs_flow_cmd_build_info() already deal with
error return code correctly, so we can handle the error condition
in a more gracefull way. Still dump a warning to preserve
debuggability.

v1 -> v2:
 - clarify the commit message
 - clean the skb and report the error (DaveM)

Fixes: ccb1352e ("net: Add Open vSwitch kernel components.")
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Connor Kuehl <connor.kuehl@canonical.com>
Signed-off-by: Kleber Sacilotto de Souza <kleber.souza@canonical.com>

net/openvswitch/datapath.c

@@ -904,7 +904,10 @@ static struct sk_buff *ovs_flow_cmd_build_info(const struct sw_flow *flow,
 	retval = ovs_flow_cmd_fill_info(flow, dp_ifindex, skb,
 					info->snd_portid, info->snd_seq, 0,
 					cmd, ufid_flags);
-	BUG_ON(retval < 0);
+	if (WARN_ON_ONCE(retval < 0)) {
+		kfree_skb(skb);
+		skb = ERR_PTR(retval);
+	}
 	return skb;
 }