[libvirt] [PATCH 2/5] util: don't log error in virNetDevVPortProfileGetStatus if instanceId is NULL

[Laine Stump]

virNetDevVPortProfileGetStatus() would log the following error:

   Could not find netlink response with expected parameters

anytime a port profile DISASSOCIATE operation was done for 802.1Qbh,
even though the disassociate had been successfully completely. Then,
due to the fortunate coincidence of status having been initialized to
0 and then not changed when the "failure" was encountered, it would
still return a status of 0 (PORT_VDP_RESPONSE_SUCCESS), so the caller
would assume a successful operation.

This would result in a spurious log message though, and would fill in
LastErrorMessage, so that the API would return that error if it
happened during cleanup from some other error. That, in turn, would
lead to an incorrect supposition that the response to the port profile
disassociate was the cause of the failure.

During debugging, I noticed that the VF in question usually had *no
uuid* associated with it (big surprise), so the solution is *not* to
send the previous instanceId down.

This patch fixes virNetDevVPortProfileGetStatus() to only check the
VF's uuid in the status if it was given an instanceId to check
against. Otherwise it only checks that the particular VF is present
(it will be).

This does cause a difference in behavior, so I want confirmation from
Cisco and IBM that this behavior change is desired (or at least not
*un*desired) - rather than returning with status unchanged (and thus
always 0, aka PORT_VDP_RESPONSE_SUCCESS) when instanceId is NULL, it
will actually get the IFLA_PORT_RESPONSE. This could lead to
revelation of error conditions we were previously ignoring. Or
not. Only experimentation will tell. Note that for 802.1Qbg instanceId
is *always* NULL, and for 802.1Qbh, it is NULL for all DISASSOCIATE
commands.

--- src/util/virnetdevvportprofile.c | 26
+++++++++++++++++--------- 1 file changed, 17 insertions(+), 9
deletions(-)

diff --git a/src/util/virnetdevvportprofile.c b/src/util/virnetdevvportprofile.c
index d0d4552..427c67b 100644
--- a/src/util/virnetdevvportprofile.c
+++ b/src/util/virnetdevvportprofile.c
@@ -1,5 +1,5 @@
 /*
- * Copyright (C) 2009-2014 Red Hat, Inc.
+ * Copyright (C) 2009-2015 Red Hat, Inc.
  *
  * This library is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
@@ -544,14 +544,22 @@ virNetDevVPortProfileGetStatus(struct nlattr **tb, int32_t vf,
                     goto cleanup;
                 }
 
-                if (instanceId &&
-                    tb_port[IFLA_PORT_INSTANCE_UUID] &&
-                    !memcmp(instanceId,
-                            (unsigned char *)
-                                   RTA_DATA(tb_port[IFLA_PORT_INSTANCE_UUID]),
-                            VIR_UUID_BUFLEN) &&
-                    tb_port[IFLA_PORT_VF] &&
-                    vf == *(uint32_t *)RTA_DATA(tb_port[IFLA_PORT_VF])) {
+                /* This ensures that the given VF is present in the
+                 * IFLA_VF_PORTS list, and that its uuid matches the
+                 * instanceId (in case we've associated it). If no
+                 * instanceId is sent from the caller, that means we've
+                 * disassociated it from this instanceId, and the uuid
+                 * will either be unset (if still not associated with
+                 * anything) or will be set to a new and different uuid
+                 */
+                if ((tb_port[IFLA_PORT_VF] &&
+                     vf == *(uint32_t *)RTA_DATA(tb_port[IFLA_PORT_VF])) &&
+                    (!instanceId ||
+                     (tb_port[IFLA_PORT_INSTANCE_UUID] &&
+                      !memcmp(instanceId,
+                              (unsigned char *)
+                              RTA_DATA(tb_port[IFLA_PORT_INSTANCE_UUID]),
+                              VIR_UUID_BUFLEN)))) {
                         found = true;
                         break;
                 }
-- 
2.5.0