From: Yuan Yuan <yyuanam@amazon.com>
Date: Wed, 22 Sep 2021 20:02:40 +0000 (+0000)
Subject: Zebra: Ignore the failure of startup intf lookup.
X-Git-Url: https://git.puffer.fish/?a=commitdiff_plain;h=5664b80ac1f1e1a98f3aca87cea42548dd75e4e4;p=matthieu%2Ffrr.git

Zebra: Ignore the failure of startup intf lookup.

In startup, zebra would dump interface information from Kernel in 3
steps w/o lock: step1, get interface information; step2, get interface
ipv4 address; step3, get interface ipv6 address.
If any interface gets added after step1, but before step2/3, zebra
would get extra interface addresses in step2/3 that has not been added
into zebra in step1. Returning error in the referenced interface lookup
would cause the startup interface retrieval to be incomplete.

Signed-off-by: Yuan Yuan <yyuanam@amazon.com>
(cherry picked from commit 8eec31ef564dcf4e096e700a648570973ca4e96b)
---

diff --git a/zebra/if_netlink.c b/zebra/if_netlink.c
index a51e0b82cb..d2774a1e63 100644
--- a/zebra/if_netlink.c
+++ b/zebra/if_netlink.c
@@ -1301,11 +1301,22 @@ int netlink_interface_addr(struct nlmsghdr *h, ns_id_t ns_id, int startup)
 
 	ifp = if_lookup_by_index_per_ns(zns, ifa->ifa_index);
 	if (ifp == NULL) {
-		flog_err(
-			EC_LIB_INTERFACE,
-			"netlink_interface_addr can't find interface by index %d",
-			ifa->ifa_index);
-		return -1;
+		if (startup) {
+			/* During startup, failure to lookup the referenced
+			 * interface should not be an error, so we have
+			 * downgraded this condition to warning, and we permit
+			 * the startup interface state retrieval to continue.
+			 */
+			flog_warn(EC_LIB_INTERFACE,
+				  "%s: can't find interface by index %d",
+				  __func__, ifa->ifa_index);
+			return 0;
+		} else {
+			flog_err(EC_LIB_INTERFACE,
+				 "%s: can't find interface by index %d",
+				 __func__, ifa->ifa_index);
+			return -1;
+		}
 	}
 
 	/* Flags passed through */