From f709377301b919a9fcbfc366e33057f7848bee28 Mon Sep 17 00:00:00 2001
From: Jiri Denemark <jdenemar@redhat.com>
Date: Thu, 5 Sep 2019 15:35:35 +0200
Subject: [PATCH] qemu: Fix qemuDomainObjTaint with virtlogd
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When virtlogd is used to capture QEMU's stdout, qemuDomainObjTaint would
always fail to write the message to the log file when QEMU is already
running (i.e., outside qemuProcessLaunch). This can happen during device
hotplug or by sending a custom QEMU guest agent command:

    warning : qemuDomainObjTaint:8757 : Domain id=9 name='blaf'
        uuid=9cfa4e37-2930-405b-bcb4-faac1829dad8 is tainted:
        custom-ga-command
    error : virLogHandlerDomainOpenLogFile:388 : Cannot open log file:
        '/var/log/libvirt/qemu/blaf.log': Device or resource busy
    error : virNetClientProgramDispatchError:172 : Cannot open log file:
        '/var/log/libvirt/qemu/blaf.log': Device or resource busy

The fix is easy, we just need to use the right API for appending a
message to QEMU log file instead of creating a new log context.

Signed-off-by: Jiri Denemark <jdenemar@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>
---
 src/qemu/qemu_domain.c | 30 ++++++++++++++----------------
 1 file changed, 14 insertions(+), 16 deletions(-)

diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
index c7eb0b5e9a..709e4e568b 100644
--- a/src/qemu/qemu_domain.c
+++ b/src/qemu/qemu_domain.c
@@ -8783,9 +8783,9 @@ void qemuDomainObjTaint(virQEMUDriverPtr driver,
                         qemuDomainLogContextPtr logCtxt)
 {
     virErrorPtr orig_err = NULL;
-    bool closeLog = false;
     char *timestamp = NULL;
     char uuidstr[VIR_UUID_STRING_BUFLEN];
+    int rc;
 
     if (!virDomainObjTaint(obj, taint))
         return;
@@ -8806,27 +8806,25 @@ void qemuDomainObjTaint(virQEMUDriverPtr driver,
     if (!(timestamp = virTimeStringNow()))
         goto cleanup;
 
-    if (logCtxt == NULL) {
-        logCtxt = qemuDomainLogContextNew(driver, obj,
-                                          QEMU_DOMAIN_LOG_CONTEXT_MODE_ATTACH);
-        if (!logCtxt) {
-            VIR_WARN("Unable to open domainlog");
-            goto cleanup;
-        }
-        closeLog = true;
+    if (logCtxt) {
+        rc = qemuDomainLogContextWrite(logCtxt,
+                                       "%s: Domain id=%d is tainted: %s\n",
+                                       timestamp,
+                                       obj->def->id,
+                                       virDomainTaintTypeToString(taint));
+    } else {
+        rc = qemuDomainLogAppendMessage(driver, obj,
+                                        "%s: Domain id=%d is tainted: %s\n",
+                                        timestamp,
+                                        obj->def->id,
+                                        virDomainTaintTypeToString(taint));
     }
 
-    if (qemuDomainLogContextWrite(logCtxt,
-                                  "%s: Domain id=%d is tainted: %s\n",
-                                  timestamp,
-                                  obj->def->id,
-                                  virDomainTaintTypeToString(taint)) < 0)
+    if (rc < 0)
         virResetLastError();
 
  cleanup:
     VIR_FREE(timestamp);
-    if (closeLog)
-        virObjectUnref(logCtxt);
     if (orig_err) {
         virSetError(orig_err);
         virFreeError(orig_err);