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[libvirt] PATCH: Remove PID file before starting QEMU, and after shutdown



We spawn QEMU with a -pidfile option to write its PID out to a file. This
file is never removed though, so next time the guest starts there is small
race condition where we might be unlucky enough to read the old PID out of
the file, instead of the new QEMU PID.  This patch adds a call to remove
the pidfile from disk when a guest is shut down. As an extra preventative
measure, we also delete it before starting a guest 

Daniel

diff -r ba0066a358b6 src/qemu_driver.c
--- a/src/qemu_driver.c	Mon Apr 20 12:10:15 2009 +0100
+++ b/src/qemu_driver.c	Mon Apr 20 13:52:47 2009 +0100
@@ -1389,6 +1389,14 @@ static int qemudStartVMDaemon(virConnect
     if (qemuPrepareHostDevices(conn, vm->def) < 0)
         goto cleanup;
 
+    if ((ret = virFileDeletePid(driver->stateDir, vm->def->name)) != 0) {
+        virReportSystemError(conn, ret,
+                             _("Cannot remove stale PID file for %s"),
+                             vm->def->name);
+        goto cleanup;
+    }
+
+
     vm->def->id = driver->nextvmid++;
     if (qemudBuildCommandLine(conn, driver, vm->def,
                               qemuCmdFlags, &argv, &progenv,
@@ -1512,6 +1520,8 @@ cleanup:
 static void qemudShutdownVMDaemon(virConnectPtr conn ATTRIBUTE_UNUSED,
                                   struct qemud_driver *driver,
                                   virDomainObjPtr vm) {
+    int ret;
+
     if (!virDomainIsActive(vm))
         return;
 
@@ -1556,6 +1566,12 @@ static void qemudShutdownVMDaemon(virCon
         VIR_WARN(_("Failed to remove domain status for %s"),
                  vm->def->name);
     }
+    if ((ret = virFileDeletePid(driver->stateDir, vm->def->name)) != 0) {
+        char ebuf[1024];
+        VIR_WARN(_("Failed to remove PID file for %s: %s"),
+                 vm->def->name, virStrerror(errno, ebuf, sizeof ebuf));
+    }
+
     vm->pid = -1;
     vm->def->id = -1;
     vm->state = VIR_DOMAIN_SHUTOFF;


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