[libvirt] [PATCH] qemu: Try multiple times to open unix monitor socket

[Cole Robinson <crobinso@xxxxxxxxxx>]

Unlike the pty monitor (which we know exists since we scrape its path from
stdout), we have no way of knowing that the unix monitor socket should exist/
be initialized. As a result, some of my KVM guests randomly fail to start on
F10 host.

Try to open the unix socket in a 3 second timeout loop. Ignore EACCES (path
does not exist if a first time run) and ECONNREFUSED (leftover socket from
a previous run hasn't been removed yet). Fixes things for me.
---
 src/qemu_driver.c |   22 +++++++++++++++++++++-
 1 files changed, 21 insertions(+), 1 deletions(-)

diff --git a/src/qemu_driver.c b/src/qemu_driver.c
index e2b7acb..200718b 100644
--- a/src/qemu_driver.c
+++ b/src/qemu_driver.c
@@ -874,6 +874,8 @@ qemudOpenMonitorUnix(virConnectPtr conn,
 {
     struct sockaddr_un addr;
     int monfd;
+    int timeout = 3; /* In seconds */
+    int ret, i;
 
     if ((monfd = socket(AF_UNIX, SOCK_STREAM, 0)) < 0) {
         virReportSystemError(conn, errno,
@@ -885,10 +887,28 @@ qemudOpenMonitorUnix(virConnectPtr conn,
     addr.sun_family = AF_UNIX;
     strncpy(addr.sun_path, monitor, sizeof(addr.sun_path));
 
-    if (connect(monfd, (struct sockaddr *) &addr, sizeof(addr)) < 0) {
+    do {
+        ret = connect(monfd, (struct sockaddr *) &addr, sizeof(addr));
+
+        if (ret == 0)
+            break;
+
+        if (errno == EACCES || errno == ECONNREFUSED) {
+            /* EACCES       : Socket may not have shown up yet
+             * ECONNREFUSED : Leftover socket hasn't been removed yet */
+            continue;
+        }
+
         virReportSystemError(conn, errno, "%s",
                              _("failed to connect to monitor socket"));
         goto error;
+
+    } while ((++i <= timeout*5) && (usleep(.2 * 1000000) <= 0));
+
+    if (ret != 0) {
+        virReportSystemError(conn, errno, "%s",
+                             _("monitor socket did not show up."));
+        goto error;
     }
 
     if (qemudOpenMonitorCommon(conn, driver, vm, monfd, reconnect) < 0)
-- 
1.6.0.6

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