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,

On Mon, 2012-03-12 at 14:00 +0100, Michal Privoznik wrote: Thanks. I didn't know that. As the comment says, I added it for the internal tests. It appeared to me that they don't go through the driver init code where I inserted the call to to the init function below. The tests were hanging at the first attempt to acquire the mutex. It could have been a defect in my patches at that time [that may still be there?]. When I inserted the static initializer, the tests passed. That was back on the 0.8.8 ubuntu natty code base. I'll pull it out and see if they pass w/o it, now that the tests all seem to pass otherwise. They certainly pass w/o this patch applied, but they're all single threaded, right? Bigger question is: is the mutex actually needed at all? I.e., can I assume that the driver is always locked -- in practice, not necessarily for the tests -- when the probes are called? Lee