[libvirt] [PATCH RFC 8/8] add qemu cache mutex

[Lee Schermerhorn]

Add a mutex for access to the qemu emulator cache.  Not clear that
this is actually needed -- driver should be locked across calls [?].
The patch can be dropped if not needed.
---
 src/qemu/qemu_capabilities.c |   18 +++++++++++++++++-
 src/qemu/qemu_capabilities.h |    2 ++
 src/qemu/qemu_driver.c       |    3 +++
 3 files changed, 22 insertions(+), 1 deletion(-)

Index: libvirt-0.9.10/src/qemu/qemu_capabilities.c
===================================================================
--- libvirt-0.9.10.orig/src/qemu/qemu_capabilities.c
+++ libvirt-0.9.10/src/qemu/qemu_capabilities.c
@@ -27,6 +27,7 @@
 #include "memory.h"
 #include "logging.h"
 #include "virterror_internal.h"
+#include "threads.h"
 #include "util.h"
 #include "virfile.h"
 #include "nodeinfo.h"
@@ -180,6 +181,11 @@ enum qemuCapsProbes {
     QEMU_PROBE_SIZE
 };
 
+/*
+ * Use static initializer for tests
+ */
+static virMutex qemuEmulatorCacheMutex = { PTHREAD_MUTEX_INITIALIZER };
+
 typedef struct _qemuEmulatorCache qemuEmulatorCache;
 typedef qemuEmulatorCache* qemuEmulatorCachePtr;
 struct _qemuEmulatorCache {
@@ -206,9 +212,17 @@ qemuEmulatorCachedInfoGet(enum qemuCapsP
                           const char *binary,
                           const char *arch);
 
+int
+qemuCapsCacheInit(void)
+{
+    return virMutexInit(&qemuEmulatorCacheMutex);
+}
+
 static void
 qemuEmulatorCachedInfoRelease(qemuEmulatorCachePtr emulator ATTRIBUTE_UNUSED)
-{ }
+{
+    virMutexUnlock(&qemuEmulatorCacheMutex);
+}
 
 /* Feature flags for the architecture info */
 static const struct qemu_feature_flags const arch_info_i686_flags [] = {
@@ -1769,6 +1783,8 @@ qemuEmulatorCachedInfoGet(enum qemuCapsP
     bool alreadyCached;
     int i;
 
+    virMutexLock(&qemuEmulatorCacheMutex);
+
     if (stat(binary, &st) != 0) {
         char ebuf[1024];
         VIR_INFO("Failed to stat emulator %s : %s",
Index: libvirt-0.9.10/src/qemu/qemu_driver.c
===================================================================
--- libvirt-0.9.10.orig/src/qemu/qemu_driver.c
+++ libvirt-0.9.10/src/qemu/qemu_driver.c
@@ -585,6 +585,9 @@ qemudStartup(int privileged) {
     if (qemuSecurityInit(qemu_driver) < 0)
         goto error;
 
+    if (qemuCapsCacheInit() < 0)
+        goto error;
+
     if ((qemu_driver->caps = qemuCreateCapabilities(NULL,
                                                     qemu_driver)) == NULL)
         goto error;
Index: libvirt-0.9.10/src/qemu/qemu_capabilities.h
===================================================================
--- libvirt-0.9.10.orig/src/qemu/qemu_capabilities.h
+++ libvirt-0.9.10/src/qemu/qemu_capabilities.h
@@ -139,6 +139,8 @@ void qemuCapsClear(virBitmapPtr caps,
 bool qemuCapsGet(virBitmapPtr caps,
                  enum qemuCapsFlags flag);
 
+int qemuCapsCacheInit(void);
+
 virCapsPtr qemuCapsInit(virCapsPtr old_caps);
 
 int qemuCapsProbeMachineTypes(const char *binary,