[libvirt] [PATCH 4/5] Convert QEMU driver mutex into a rwlock

A number of driver API methods which acquire the driver mutex only ever used the driver object in a read-only fashion. All these uses are converted to call qemuDriverLockRO() allowing for greater concurrency. * src/qemu/qemu_conf.h: s/Mutex/RWLock/ * src/qemu/qemu_driver.c: Add a qemuDriverLockRO() method and use it anywhere that doesn't require a write lock on the driver --- src/qemu/qemu_conf.h | 2 +- src/qemu/qemu_driver.c | 100 +++++++++++++++++++++++++++-------------------- 2 files changed, 58 insertions(+), 44 deletions(-) diff --git a/src/qemu/qemu_conf.h b/src/qemu/qemu_conf.h index f9a970f..a6e68f8 100644 --- a/src/qemu/qemu_conf.h +++ b/src/qemu/qemu_conf.h @@ -75,7 +75,7 @@ enum qemud_cmd_flags { /* Main driver state */ struct qemud_driver { - virMutex lock; + virRWLock lock; int privileged; diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c index 1eb7797..19187ac 100644 --- a/src/qemu/qemu_driver.c +++ b/src/qemu/qemu_driver.c @@ -78,13 +78,19 @@ static int qemudShutdown(void); +/* Obtains a full write lock */ static void qemuDriverLock(struct qemud_driver *driver) { - virMutexLock(&driver->lock); + virRWLockWrite(&driver->lock); +} +/* Obtains a read-only lock */ +static void qemuDriverLockRO(struct qemud_driver *driver) +{ + virRWLockRead(&driver->lock); } static void qemuDriverUnlock(struct qemud_driver *driver) { - virMutexUnlock(&driver->lock); + virRWLockUnlock(&driver->lock); } static void qemuDomainEventFlush(int timer, void *opaque); @@ -431,8 +437,8 @@ qemudStartup(int privileged) { if (VIR_ALLOC(qemu_driver) < 0) return -1; - if (virMutexInit(&qemu_driver->lock) < 0) { - VIR_ERROR("%s", _("cannot initialize mutex")); + if (virRWLockInit(&qemu_driver->lock) < 0) { + VIR_ERROR("%s", _("cannot initialize rwlock")); VIR_FREE(qemu_driver); return -1; } @@ -743,7 +749,7 @@ qemudShutdown(void) { virCgroupFree(&qemu_driver->cgroup); qemuDriverUnlock(qemu_driver); - virMutexDestroy(&qemu_driver->lock); + virRWLockDestroy(&qemu_driver->lock); VIR_FREE(qemu_driver); return 0; @@ -2262,7 +2268,7 @@ qemudDispatchVMEvent(int watch, int fd, int events, void *opaque) { * the VM must be running. Nowhere is allowed to remove * a domain while it is running, so it is safe to not * lock the driver here... */ - qemuDriverLock(driver); + qemuDriverLockRO(driver); virDomainObjLock(vm); qemuDriverUnlock(driver); @@ -2520,7 +2526,7 @@ static virDomainPtr qemudDomainLookupByID(virConnectPtr conn, virDomainObjPtr vm; virDomainPtr dom = NULL; - qemuDriverLock(driver); + qemuDriverLockRO(driver); vm = virDomainFindByID(&driver->domains, id); qemuDriverUnlock(driver); @@ -2545,7 +2551,7 @@ static virDomainPtr qemudDomainLookupByUUID(virConnectPtr conn, virDomainObjPtr vm; virDomainPtr dom = NULL; - qemuDriverLock(driver); + qemuDriverLockRO(driver); vm = virDomainFindByUUID(&driver->domains, uuid); qemuDriverUnlock(driver); @@ -2572,7 +2578,7 @@ static virDomainPtr qemudDomainLookupByName(virConnectPtr conn, virDomainObjPtr vm; virDomainPtr dom = NULL; - qemuDriverLock(driver); + qemuDriverLockRO(driver); vm = virDomainFindByName(&driver->domains, name); qemuDriverUnlock(driver); @@ -2626,7 +2632,7 @@ static int qemudListDomains(virConnectPtr conn, int *ids, int nids) { struct qemud_driver *driver = conn->privateData; int n; - qemuDriverLock(driver); + qemuDriverLockRO(driver); n = virDomainObjListGetActiveIDs(&driver->domains, ids, nids); qemuDriverUnlock(driver); @@ -2637,7 +2643,7 @@ static int qemudNumDomains(virConnectPtr conn) { struct qemud_driver *driver = conn->privateData; int n; - qemuDriverLock(driver); + qemuDriverLockRO(driver); n = virDomainObjListNumOfDomains(&driver->domains, 1); qemuDriverUnlock(driver); @@ -2731,7 +2737,7 @@ static int qemudDomainSuspend(virDomainPtr dom) { int ret = -1; virDomainEventPtr event = NULL; - qemuDriverLock(driver); + qemuDriverLockRO(driver); vm = virDomainFindByUUID(&driver->domains, dom->uuid); if (!vm) { @@ -2761,7 +2767,9 @@ static int qemudDomainSuspend(virDomainPtr dom) { cleanup: if (vm) virDomainObjUnlock(vm); + qemuDriverUnlock(driver); + qemuDriverLock(driver); if (event) qemuDomainEventQueue(driver, event); qemuDriverUnlock(driver); @@ -2775,7 +2783,7 @@ static int qemudDomainResume(virDomainPtr dom) { int ret = -1; virDomainEventPtr event = NULL; - qemuDriverLock(driver); + qemuDriverLockRO(driver); vm = virDomainFindByUUID(&driver->domains, dom->uuid); if (!vm) { @@ -2809,6 +2817,8 @@ static int qemudDomainResume(virDomainPtr dom) { cleanup: if (vm) virDomainObjUnlock(vm); + qemuDriverUnlock(driver); + qemuDriverLock(driver); if (event) qemuDomainEventQueue(driver, event); qemuDriverUnlock(driver); @@ -2821,7 +2831,7 @@ static int qemudDomainShutdown(virDomainPtr dom) { virDomainObjPtr vm; int ret = -1; - qemuDriverLock(driver); + qemuDriverLockRO(driver); vm = virDomainFindByUUID(&driver->domains, dom->uuid); qemuDriverUnlock(driver); @@ -2898,7 +2908,7 @@ static char *qemudDomainGetOSType(virDomainPtr dom) { virDomainObjPtr vm; char *type = NULL; - qemuDriverLock(driver); + qemuDriverLockRO(driver); vm = virDomainFindByUUID(&driver->domains, dom->uuid); qemuDriverUnlock(driver); if (!vm) { @@ -2924,7 +2934,7 @@ static unsigned long qemudDomainGetMaxMemory(virDomainPtr dom) { virDomainObjPtr vm; unsigned long ret = 0; - qemuDriverLock(driver); + qemuDriverLockRO(driver); vm = virDomainFindByUUID(&driver->domains, dom->uuid); qemuDriverUnlock(driver); @@ -2949,7 +2959,7 @@ static int qemudDomainSetMaxMemory(virDomainPtr dom, unsigned long newmax) { virDomainObjPtr vm; int ret = -1; - qemuDriverLock(driver); + qemuDriverLockRO(driver); vm = virDomainFindByUUID(&driver->domains, dom->uuid); qemuDriverUnlock(driver); @@ -2982,7 +2992,7 @@ static int qemudDomainSetMemory(virDomainPtr dom, unsigned long newmem) { virDomainObjPtr vm; int ret = -1; - qemuDriverLock(driver); + qemuDriverLockRO(driver); vm = virDomainFindByUUID(&driver->domains, dom->uuid); qemuDriverUnlock(driver); if (!vm) { @@ -3029,7 +3039,7 @@ static int qemudDomainGetInfo(virDomainPtr dom, int err; unsigned long balloon; - qemuDriverLock(driver); + qemuDriverLockRO(driver); vm = virDomainFindByUUID(&driver->domains, dom->uuid); qemuDriverUnlock(driver); if (!vm) { @@ -3257,7 +3267,7 @@ static int qemudDomainCoreDump(virDomainPtr dom, NULL, }; - qemuDriverLock(driver); + qemuDriverLockRO(driver); vm = virDomainFindByUUID(&driver->domains, dom->uuid); qemuDriverUnlock(driver); @@ -3314,7 +3324,7 @@ static int qemudDomainSetVcpus(virDomainPtr dom, unsigned int nvcpus) { int ret = -1; const char *type; - qemuDriverLock(driver); + qemuDriverLockRO(driver); vm = virDomainFindByUUID(&driver->domains, dom->uuid); qemuDriverUnlock(driver); @@ -3375,7 +3385,7 @@ qemudDomainPinVcpu(virDomainPtr dom, virNodeInfo nodeinfo; int ret = -1; - qemuDriverLock(driver); + qemuDriverLockRO(driver); vm = virDomainFindByUUID(&driver->domains, dom->uuid); qemuDriverUnlock(driver); @@ -3444,7 +3454,7 @@ qemudDomainGetVcpus(virDomainPtr dom, int i, v, maxcpu; int ret = -1; - qemuDriverLock(driver); + qemuDriverLockRO(driver); vm = virDomainFindByUUID(&driver->domains, dom->uuid); qemuDriverUnlock(driver); @@ -3533,7 +3543,7 @@ static int qemudDomainGetMaxVcpus(virDomainPtr dom) { const char *type; int ret = -1; - qemuDriverLock(driver); + qemuDriverLockRO(driver); vm = virDomainFindByUUID(&driver->domains, dom->uuid); qemuDriverUnlock(driver); @@ -3567,7 +3577,7 @@ static int qemudDomainGetSecurityLabel(virDomainPtr dom, virSecurityLabelPtr sec const char *type; int ret = -1; - qemuDriverLock(driver); + qemuDriverLockRO(driver); vm = virDomainFindByUUID(&driver->domains, dom->uuid); memset(seclabel, 0, sizeof(*seclabel)); @@ -3627,7 +3637,7 @@ static int qemudNodeGetSecurityModel(virConnectPtr conn, char *p; int ret = 0; - qemuDriverLock(driver); + qemuDriverLockRO(driver); if (!driver->securityDriver) { memset(secmodel, 0, sizeof (*secmodel)); goto cleanup; @@ -3843,7 +3853,7 @@ static char *qemudDomainDumpXML(virDomainPtr dom, unsigned long balloon; int err; - qemuDriverLock(driver); + qemuDriverLockRO(driver); vm = virDomainFindByUUID(&driver->domains, dom->uuid); qemuDriverUnlock(driver); @@ -3891,7 +3901,7 @@ static char *qemuDomainXMLFromNative(virConnectPtr conn, goto cleanup; } - qemuDriverLock(driver); + qemuDriverLockRO(driver); def = qemuParseCommandLineString(conn, driver->caps, config); qemuDriverUnlock(driver); if (!def) @@ -3921,7 +3931,7 @@ static char *qemuDomainXMLToNative(virConnectPtr conn, char *ret = NULL; int i; - qemuDriverLock(driver); + qemuDriverLockRO(driver); if (STRNEQ(format, QEMU_CONFIG_FORMAT_ARGV)) { qemudReportError(conn, NULL, NULL, VIR_ERR_INVALID_ARG, @@ -4038,7 +4048,7 @@ static int qemudListDefinedDomains(virConnectPtr conn, struct qemud_driver *driver = conn->privateData; int n; - qemuDriverLock(driver); + qemuDriverLockRO(driver); n = virDomainObjListGetInactiveNames(&driver->domains, names, nnames); qemuDriverUnlock(driver); return n; @@ -4048,7 +4058,7 @@ static int qemudNumDefinedDomains(virConnectPtr conn) { struct qemud_driver *driver = conn->privateData; int n; - qemuDriverLock(driver); + qemuDriverLockRO(driver); n = virDomainObjListNumOfDomains(&driver->domains, 0); qemuDriverUnlock(driver); @@ -4062,7 +4072,7 @@ static int qemudDomainStart(virDomainPtr dom) { int ret = -1; virDomainEventPtr event = NULL; - qemuDriverLock(driver); + qemuDriverLockRO(driver); vm = virDomainFindByUUID(&driver->domains, dom->uuid); if (!vm) { @@ -4082,6 +4092,8 @@ static int qemudDomainStart(virDomainPtr dom) { cleanup: if (vm) virDomainObjUnlock(vm); + qemuDriverUnlock(driver); + qemuDriverLock(driver); if (event) qemuDomainEventQueue(driver, event); qemuDriverUnlock(driver); @@ -5151,7 +5163,7 @@ static int qemudDomainGetAutostart(virDomainPtr dom, virDomainObjPtr vm; int ret = -1; - qemuDriverLock(driver); + qemuDriverLockRO(driver); vm = virDomainFindByUUID(&driver->domains, dom->uuid); qemuDriverUnlock(driver); @@ -5179,7 +5191,7 @@ static int qemudDomainSetAutostart(virDomainPtr dom, char *configFile = NULL, *autostartLink = NULL; int ret = -1; - qemuDriverLock(driver); + qemuDriverLockRO(driver); vm = virDomainFindByUUID(&driver->domains, dom->uuid); if (!vm) { @@ -5249,7 +5261,7 @@ static char *qemuGetSchedulerType(virDomainPtr dom, struct qemud_driver *driver = dom->conn->privateData; char *ret = NULL; - qemuDriverLock(driver); + qemuDriverLockRO(driver); if (!qemuCgroupControllerActive(driver, VIR_CGROUP_CONTROLLER_CPU)) { qemudReportError(dom->conn, dom, NULL, VIR_ERR_NO_SUPPORT, __FUNCTION__); @@ -5278,7 +5290,7 @@ static int qemuSetSchedulerParameters(virDomainPtr dom, virDomainObjPtr vm = NULL; int ret = -1; - qemuDriverLock(driver); + qemuDriverLockRO(driver); if (!qemuCgroupControllerActive(driver, VIR_CGROUP_CONTROLLER_CPU)) { qemudReportError(dom->conn, dom, NULL, VIR_ERR_NO_SUPPORT, __FUNCTION__); @@ -5343,7 +5355,7 @@ static int qemuGetSchedulerParameters(virDomainPtr dom, int ret = -1; int rc; - qemuDriverLock(driver); + qemuDriverLockRO(driver); if (!qemuCgroupControllerActive(driver, VIR_CGROUP_CONTROLLER_CPU)) { qemudReportError(dom->conn, dom, NULL, VIR_ERR_NO_SUPPORT, __FUNCTION__); @@ -5410,7 +5422,7 @@ qemudDomainBlockStats (virDomainPtr dom, virDomainObjPtr vm; virDomainDiskDefPtr disk = NULL; - qemuDriverLock(driver); + qemuDriverLockRO(driver); vm = virDomainFindByUUID(&driver->domains, dom->uuid); qemuDriverUnlock(driver); if (!vm) { @@ -5471,7 +5483,7 @@ qemudDomainInterfaceStats (virDomainPtr dom, int i; int ret = -1; - qemuDriverLock(driver); + qemuDriverLockRO(driver); vm = virDomainFindByUUID(&driver->domains, dom->uuid); qemuDriverUnlock(driver); @@ -5531,7 +5543,7 @@ qemudDomainBlockPeek (virDomainPtr dom, virDomainObjPtr vm; int fd = -1, ret = -1, i; - qemuDriverLock(driver); + qemuDriverLockRO(driver); vm = virDomainFindByUUID(&driver->domains, dom->uuid); qemuDriverUnlock(driver); @@ -5604,7 +5616,7 @@ qemudDomainMemoryPeek (virDomainPtr dom, char *tmp = NULL; int fd = -1, ret = -1; - qemuDriverLock(driver); + qemuDriverLockRO(driver); vm = virDomainFindByUUID(&driver->domains, dom->uuid); qemuDriverUnlock(driver); @@ -6759,7 +6771,7 @@ qemudDomainMigratePerform (virDomainPtr dom, int ret = -1; int paused = 0; - qemuDriverLock(driver); + qemuDriverLockRO(driver); vm = virDomainFindByUUID(&driver->domains, dom->uuid); if (!vm) { char uuidstr[VIR_UUID_STRING_BUFLEN]; @@ -6831,6 +6843,8 @@ cleanup: if (vm) virDomainObjUnlock(vm); + qemuDriverUnlock(driver); + qemuDriverLock(driver); if (event) qemuDomainEventQueue(driver, event); qemuDriverUnlock(driver); @@ -7038,7 +7052,7 @@ qemudNodeDeviceReset (virNodeDevicePtr dev) if (!pci) return -1; - qemuDriverLock(driver); + qemuDriverLockRO(driver); if (pciResetDevice(dev->conn, pci, driver->activePciHostdevs) < 0) goto out; -- 1.6.2.5