5:23 a.m.
v3 of:
https://www.redhat.com/archives/libvir-list/2019-March/msg00924.html
diff to v2:
- Dropped @enterMonitor from qemuDomainDeleteDevice,
- Simplified event checking since @vm is always locked after
@enterMonitor is dropped,
- Switched to plain qemuMonitorDelDevice for zpci device
- Added comment about error reporting to 3/5
Note that 3/5 was ACKed in v2.
Michal Prívozník (5):
qemu_hotplug: Introduce and use qemuDomainDeleteDevice
DO NOT APPLY: Simple reproducer
qemuMonitorJSONDelDevice: Return -2 on DeviceNotFound error
qemu_hotplug: Fix a rare race condition when detaching a device twice
DO NOT APPLY: Revert simple reproducer
src/qemu/qemu_domain.h | 1 +
src/qemu/qemu_hotplug.c | 278 +++++++++++++++--------------------
src/qemu/qemu_monitor.c | 10 ++
src/qemu/qemu_monitor_json.c | 5 +
4 files changed, 134 insertions(+), 160 deletions(-)
--
2.19.2
5:23 a.m.
New subject: [libvirt] [PATCH v3 1/5] qemu_hotplug: Introduce and use qemuDomainDeleteDevice
The aim of this function will be to fix return value of
qemuMonitorDelDevice() in one specific case. But that is yet to
come. Right now this is nothing but a plain substitution.
Signed-off-by: Michal Privoznik <mprivozn(a)redhat.com>
---
src/qemu/qemu_hotplug.c | 250 +++++++++++++++-------------------------
1 file changed, 90 insertions(+), 160 deletions(-)
diff --git a/src/qemu/qemu_hotplug.c b/src/qemu/qemu_hotplug.c
index f43f80668c..0a3ee2628c 100644
--- a/src/qemu/qemu_hotplug.c
+++ b/src/qemu/qemu_hotplug.c
@@ -67,6 +67,45 @@ VIR_LOG_INIT("qemu.qemu_hotplug");
unsigned long long qemuDomainRemoveDeviceWaitTime = 1000ull * 5;
+/**
+ * qemuDomainDeleteDevice:
+ * @vm: domain object
+ * @alias: device to remove
+ *
+ * This is a wrapper over qemuMonitorDelDevice() plus enter/exit
+ * monitor calls. This function MUST be used instead of plain
+ * qemuMonitorDelDevice() in all places where @alias represents a
+ * device from domain XML, i.e. caller marks the device for
+ * removal and then calls qemuDomainWaitForDeviceRemoval()
+ * followed by qemuDomainRemove*Device().
+ *
+ * For collateral devices (e.g. extension devices like zPCI) it
+ * is safe to use plain qemuMonitorDelDevice().
+ *
+ * Upon entry, @vm must be locked.
+ *
+ * Returns: 0 on success,
+ * -1 otherwise.
+ */
+static int
+qemuDomainDeleteDevice(virDomainObjPtr vm,
+ const char *alias)
+{
+ qemuDomainObjPrivatePtr priv = vm->privateData;
+ virQEMUDriverPtr driver = priv->driver;
+ int rc;
+
+ qemuDomainObjEnterMonitor(driver, vm);
+
+ rc = qemuMonitorDelDevice(priv->mon, alias);
+
+ if (qemuDomainObjExitMonitor(driver, vm) < 0)
+ rc = -1;
+
+ return rc;
+}
+
+
/**
* qemuHotplugPrepareDiskSourceAccess:
* @driver: qemu driver struct
@@ -5216,7 +5255,6 @@ qemuDomainDetachVirtioDiskDevice(virQEMUDriverPtr driver,
bool async)
{
int ret = -1;
- qemuDomainObjPrivatePtr priv = vm->privateData;
if (qemuIsMultiFunctionDevice(vm->def, &detach->info)) {
virReportError(VIR_ERR_OPERATION_FAILED,
@@ -5228,15 +5266,11 @@ qemuDomainDetachVirtioDiskDevice(virQEMUDriverPtr driver,
if (!async)
qemuDomainMarkDeviceForRemoval(vm, &detach->info);
- qemuDomainObjEnterMonitor(driver, vm);
- if (qemuMonitorDelDevice(priv->mon, detach->info.alias) < 0) {
- if (qemuDomainObjExitMonitor(driver, vm) < 0)
- goto cleanup;
- virDomainAuditDisk(vm, detach->src, NULL, "detach", false);
+ if (qemuDomainDeleteDevice(vm, detach->info.alias) < 0) {
+ if (virDomainObjIsActive(vm))
+ virDomainAuditDisk(vm, detach->src, NULL, "detach", false);
goto cleanup;
}
- if (qemuDomainObjExitMonitor(driver, vm) < 0)
- goto cleanup;
if (async) {
ret = 0;
@@ -5258,7 +5292,6 @@ qemuDomainDetachDiskDevice(virQEMUDriverPtr driver,
bool async)
{
int ret = -1;
- qemuDomainObjPrivatePtr priv = vm->privateData;
if (qemuDomainDiskBlockJobIsActive(detach))
goto cleanup;
@@ -5266,15 +5299,11 @@ qemuDomainDetachDiskDevice(virQEMUDriverPtr driver,
if (!async)
qemuDomainMarkDeviceForRemoval(vm, &detach->info);
- qemuDomainObjEnterMonitor(driver, vm);
- if (qemuMonitorDelDevice(priv->mon, detach->info.alias) < 0) {
- if (qemuDomainObjExitMonitor(driver, vm) < 0)
- goto cleanup;
- virDomainAuditDisk(vm, detach->src, NULL, "detach", false);
+ if (qemuDomainDeleteDevice(vm, detach->info.alias) < 0) {
+ if (virDomainObjIsActive(vm))
+ virDomainAuditDisk(vm, detach->src, NULL, "detach", false);
goto cleanup;
}
- if (qemuDomainObjExitMonitor(driver, vm) < 0)
- goto cleanup;
if (async) {
ret = 0;
@@ -5455,19 +5484,18 @@ int qemuDomainDetachControllerDevice(virQEMUDriverPtr driver,
if (!async)
qemuDomainMarkDeviceForRemoval(vm, &detach->info);
- qemuDomainObjEnterMonitor(driver, vm);
- if (detach->type == VIR_DOMAIN_CONTROLLER_TYPE_PCI &&
- qemuDomainDetachExtensionDevice(priv->mon, &detach->info) < 0) {
- goto exit_monitor;
- }
+ if (detach->type == VIR_DOMAIN_CONTROLLER_TYPE_PCI) {
+ int rc;
+ qemuDomainObjEnterMonitor(driver, vm);
+ rc = qemuDomainDetachExtensionDevice(priv->mon, &detach->info);
+ if (qemuDomainObjExitMonitor(driver, vm) < 0)
+ rc = -1;
- if (qemuMonitorDelDevice(priv->mon, detach->info.alias) < 0) {
- ignore_value(qemuDomainObjExitMonitor(driver, vm));
- goto cleanup;
+ if (rc < 0)
+ goto cleanup;
}
- exit_monitor:
- if (qemuDomainObjExitMonitor(driver, vm) < 0)
+ if (qemuDomainDeleteDevice(vm, detach->info.alias) < 0)
goto cleanup;
if (async) {
@@ -5484,14 +5512,11 @@ int qemuDomainDetachControllerDevice(virQEMUDriverPtr driver,
}
static int
-qemuDomainDetachHostPCIDevice(virQEMUDriverPtr driver,
- virDomainObjPtr vm,
+qemuDomainDetachHostPCIDevice(virDomainObjPtr vm,
virDomainHostdevDefPtr detach,
bool async)
{
- qemuDomainObjPrivatePtr priv = vm->privateData;
virDomainHostdevSubsysPCIPtr pcisrc = &detach->source.subsys.u.pci;
- int ret;
if (qemuIsMultiFunctionDevice(vm->def, detach->info)) {
virReportError(VIR_ERR_OPERATION_FAILED,
@@ -5504,23 +5529,14 @@ qemuDomainDetachHostPCIDevice(virQEMUDriverPtr driver,
if (!async)
qemuDomainMarkDeviceForRemoval(vm, detach->info);
- qemuDomainObjEnterMonitor(driver, vm);
- ret = qemuMonitorDelDevice(priv->mon, detach->info->alias);
- if (qemuDomainObjExitMonitor(driver, vm) < 0)
- ret = -1;
-
- return ret;
+ return qemuDomainDeleteDevice(vm, detach->info->alias);
}
static int
-qemuDomainDetachHostUSBDevice(virQEMUDriverPtr driver,
- virDomainObjPtr vm,
+qemuDomainDetachHostUSBDevice(virDomainObjPtr vm,
virDomainHostdevDefPtr detach,
bool async)
{
- qemuDomainObjPrivatePtr priv = vm->privateData;
- int ret;
-
if (!detach->info->alias) {
virReportError(VIR_ERR_OPERATION_FAILED,
"%s", _("device cannot be detached without a device
alias"));
@@ -5530,23 +5546,14 @@ qemuDomainDetachHostUSBDevice(virQEMUDriverPtr driver,
if (!async)
qemuDomainMarkDeviceForRemoval(vm, detach->info);
- qemuDomainObjEnterMonitor(driver, vm);
- ret = qemuMonitorDelDevice(priv->mon, detach->info->alias);
- if (qemuDomainObjExitMonitor(driver, vm) < 0)
- ret = -1;
-
- return ret;
+ return qemuDomainDeleteDevice(vm, detach->info->alias);
}
static int
-qemuDomainDetachHostSCSIDevice(virQEMUDriverPtr driver,
- virDomainObjPtr vm,
+qemuDomainDetachHostSCSIDevice(virDomainObjPtr vm,
virDomainHostdevDefPtr detach,
bool async)
{
- qemuDomainObjPrivatePtr priv = vm->privateData;
- int ret = -1;
-
if (!detach->info->alias) {
virReportError(VIR_ERR_OPERATION_FAILED,
"%s", _("device cannot be detached without a device
alias"));
@@ -5556,24 +5563,14 @@ qemuDomainDetachHostSCSIDevice(virQEMUDriverPtr driver,
if (!async)
qemuDomainMarkDeviceForRemoval(vm, detach->info);
- qemuDomainObjEnterMonitor(driver, vm);
- ret = qemuMonitorDelDevice(priv->mon, detach->info->alias);
-
- if (qemuDomainObjExitMonitor(driver, vm) < 0)
- return -1;
-
- return ret;
+ return qemuDomainDeleteDevice(vm, detach->info->alias);
}
static int
-qemuDomainDetachSCSIVHostDevice(virQEMUDriverPtr driver,
- virDomainObjPtr vm,
+qemuDomainDetachSCSIVHostDevice(virDomainObjPtr vm,
virDomainHostdevDefPtr detach,
bool async)
{
- qemuDomainObjPrivatePtr priv = vm->privateData;
- int ret = -1;
-
if (!detach->info->alias) {
virReportError(VIR_ERR_OPERATION_FAILED,
"%s", _("device cannot be detached without a device
alias"));
@@ -5583,25 +5580,15 @@ qemuDomainDetachSCSIVHostDevice(virQEMUDriverPtr driver,
if (!async)
qemuDomainMarkDeviceForRemoval(vm, detach->info);
- qemuDomainObjEnterMonitor(driver, vm);
- ret = qemuMonitorDelDevice(priv->mon, detach->info->alias);
-
- if (qemuDomainObjExitMonitor(driver, vm) < 0)
- return -1;
-
- return ret;
+ return qemuDomainDeleteDevice(vm, detach->info->alias);
}
static int
-qemuDomainDetachMediatedDevice(virQEMUDriverPtr driver,
- virDomainObjPtr vm,
+qemuDomainDetachMediatedDevice(virDomainObjPtr vm,
virDomainHostdevDefPtr detach,
bool async)
{
- int ret = -1;
- qemuDomainObjPrivatePtr priv = vm->privateData;
-
if (!detach->info->alias) {
virReportError(VIR_ERR_OPERATION_FAILED, "%s",
_("device cannot be detached without a device alias"));
@@ -5611,12 +5598,7 @@ qemuDomainDetachMediatedDevice(virQEMUDriverPtr driver,
if (!async)
qemuDomainMarkDeviceForRemoval(vm, detach->info);
- qemuDomainObjEnterMonitor(driver, vm);
- ret = qemuMonitorDelDevice(priv->mon, detach->info->alias);
- if (qemuDomainObjExitMonitor(driver, vm) < 0)
- ret = -1;
-
- return ret;
+ return qemuDomainDeleteDevice(vm, detach->info->alias);
}
@@ -5633,19 +5615,19 @@ qemuDomainDetachThisHostDevice(virQEMUDriverPtr driver,
switch (detach->source.subsys.type) {
case VIR_DOMAIN_HOSTDEV_SUBSYS_TYPE_PCI:
- ret = qemuDomainDetachHostPCIDevice(driver, vm, detach, async);
+ ret = qemuDomainDetachHostPCIDevice(vm, detach, async);
break;
case VIR_DOMAIN_HOSTDEV_SUBSYS_TYPE_USB:
- ret = qemuDomainDetachHostUSBDevice(driver, vm, detach, async);
+ ret = qemuDomainDetachHostUSBDevice(vm, detach, async);
break;
case VIR_DOMAIN_HOSTDEV_SUBSYS_TYPE_SCSI:
- ret = qemuDomainDetachHostSCSIDevice(driver, vm, detach, async);
+ ret = qemuDomainDetachHostSCSIDevice(vm, detach, async);
break;
case VIR_DOMAIN_HOSTDEV_SUBSYS_TYPE_SCSI_HOST:
- ret = qemuDomainDetachSCSIVHostDevice(driver, vm, detach, async);
+ ret = qemuDomainDetachSCSIVHostDevice(vm, detach, async);
break;
case VIR_DOMAIN_HOSTDEV_SUBSYS_TYPE_MDEV:
- ret = qemuDomainDetachMediatedDevice(driver, vm, detach, async);
+ ret = qemuDomainDetachMediatedDevice(vm, detach, async);
break;
default:
virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
@@ -5762,7 +5744,6 @@ qemuDomainDetachShmemDevice(virQEMUDriverPtr driver,
int ret = -1;
ssize_t idx = -1;
virDomainShmemDefPtr shmem = NULL;
- qemuDomainObjPrivatePtr priv = vm->privateData;
if ((idx = virDomainShmemDefFind(vm->def, dev)) < 0) {
virReportError(VIR_ERR_DEVICE_MISSING,
@@ -5791,12 +5772,7 @@ qemuDomainDetachShmemDevice(virQEMUDriverPtr driver,
if (!async)
qemuDomainMarkDeviceForRemoval(vm, &shmem->info);
- qemuDomainObjEnterMonitor(driver, vm);
- if (qemuMonitorDelDevice(priv->mon, shmem->info.alias) < 0) {
- ignore_value(qemuDomainObjExitMonitor(driver, vm));
- goto cleanup;
- }
- if (qemuDomainObjExitMonitor(driver, vm) < 0)
+ if (qemuDomainDeleteDevice(vm, shmem->info.alias) < 0)
goto cleanup;
if (async) {
@@ -5821,7 +5797,6 @@ qemuDomainDetachWatchdog(virQEMUDriverPtr driver,
{
int ret = -1;
virDomainWatchdogDefPtr watchdog = vm->def->watchdog;
- qemuDomainObjPrivatePtr priv = vm->privateData;
if (!watchdog) {
virReportError(VIR_ERR_DEVICE_MISSING, "%s",
@@ -5852,12 +5827,7 @@ qemuDomainDetachWatchdog(virQEMUDriverPtr driver,
if (!async)
qemuDomainMarkDeviceForRemoval(vm, &watchdog->info);
- qemuDomainObjEnterMonitor(driver, vm);
- if (qemuMonitorDelDevice(priv->mon, watchdog->info.alias) < 0) {
- ignore_value(qemuDomainObjExitMonitor(driver, vm));
- goto cleanup;
- }
- if (qemuDomainObjExitMonitor(driver, vm) < 0)
+ if (qemuDomainDeleteDevice(vm, watchdog->info.alias) < 0)
goto cleanup;
if (async) {
@@ -5881,7 +5851,6 @@ qemuDomainDetachRedirdevDevice(virQEMUDriverPtr driver,
bool async)
{
int ret = -1;
- qemuDomainObjPrivatePtr priv = vm->privateData;
virDomainRedirdevDefPtr tmpRedirdevDef;
ssize_t idx;
@@ -5902,12 +5871,7 @@ qemuDomainDetachRedirdevDevice(virQEMUDriverPtr driver,
if (!async)
qemuDomainMarkDeviceForRemoval(vm, &tmpRedirdevDef->info);
- qemuDomainObjEnterMonitor(driver, vm);
- if (qemuMonitorDelDevice(priv->mon, tmpRedirdevDef->info.alias) < 0) {
- ignore_value(qemuDomainObjExitMonitor(driver, vm));
- goto cleanup;
- }
- if (qemuDomainObjExitMonitor(driver, vm) < 0)
+ if (qemuDomainDeleteDevice(vm, tmpRedirdevDef->info.alias) < 0)
goto cleanup;
if (async) {
@@ -5932,7 +5896,6 @@ qemuDomainDetachNetDevice(virQEMUDriverPtr driver,
{
int detachidx, ret = -1;
virDomainNetDefPtr detach = NULL;
- qemuDomainObjPrivatePtr priv = vm->privateData;
if ((detachidx = virDomainNetFindIdx(vm->def, dev->data.net)) < 0)
goto cleanup;
@@ -5973,15 +5936,11 @@ qemuDomainDetachNetDevice(virQEMUDriverPtr driver,
if (!async)
qemuDomainMarkDeviceForRemoval(vm, &detach->info);
- qemuDomainObjEnterMonitor(driver, vm);
- if (qemuMonitorDelDevice(priv->mon, detach->info.alias) < 0) {
- if (qemuDomainObjExitMonitor(driver, vm) < 0)
- goto cleanup;
- virDomainAuditNet(vm, detach, NULL, "detach", false);
+ if (qemuDomainDeleteDevice(vm, detach->info.alias) < 0) {
+ if (virDomainObjIsActive(vm))
+ virDomainAuditNet(vm, detach, NULL, "detach", false);
goto cleanup;
}
- if (qemuDomainObjExitMonitor(driver, vm) < 0)
- goto cleanup;
if (async) {
ret = 0;
@@ -6144,20 +6103,19 @@ int qemuDomainDetachChrDevice(virQEMUDriverPtr driver,
if (!async && !guestfwd)
qemuDomainMarkDeviceForRemoval(vm, &tmpChr->info);
- qemuDomainObjEnterMonitor(driver, vm);
if (guestfwd) {
- if (qemuMonitorRemoveNetdev(priv->mon, tmpChr->info.alias) < 0) {
- ignore_value(qemuDomainObjExitMonitor(driver, vm));
+ int rc;
+ qemuDomainObjEnterMonitor(driver, vm);
+ rc = qemuMonitorRemoveNetdev(priv->mon, tmpChr->info.alias);
+ if (qemuDomainObjExitMonitor(driver, vm) < 0)
+ rc = -1;
+
+ if (rc < 0)
goto cleanup;
- }
} else {
- if (qemuMonitorDelDevice(priv->mon, tmpChr->info.alias) < 0) {
- ignore_value(qemuDomainObjExitMonitor(driver, vm));
+ if (qemuDomainDeleteDevice(vm, tmpChr->info.alias) < 0)
goto cleanup;
- }
}
- if (qemuDomainObjExitMonitor(driver, vm) < 0)
- goto cleanup;
if (guestfwd) {
ret = qemuDomainRemoveChrDevice(driver, vm, tmpChr, false);
@@ -6181,10 +6139,8 @@ qemuDomainDetachRNGDevice(virQEMUDriverPtr driver,
virDomainRNGDefPtr rng,
bool async)
{
- qemuDomainObjPrivatePtr priv = vm->privateData;
ssize_t idx;
virDomainRNGDefPtr tmpRNG;
- int rc;
int ret = -1;
if ((idx = virDomainRNGFind(vm->def, rng)) < 0) {
@@ -6206,9 +6162,7 @@ qemuDomainDetachRNGDevice(virQEMUDriverPtr driver,
if (!async)
qemuDomainMarkDeviceForRemoval(vm, &tmpRNG->info);
- qemuDomainObjEnterMonitor(driver, vm);
- rc = qemuMonitorDelDevice(priv->mon, tmpRNG->info.alias);
- if (qemuDomainObjExitMonitor(driver, vm) || rc < 0)
+ if (qemuDomainDeleteDevice(vm, tmpRNG->info.alias) < 0)
goto cleanup;
if (async) {
@@ -6231,10 +6185,8 @@ qemuDomainDetachMemoryDevice(virQEMUDriverPtr driver,
virDomainMemoryDefPtr memdef,
bool async)
{
- qemuDomainObjPrivatePtr priv = vm->privateData;
virDomainMemoryDefPtr mem;
int idx;
- int rc;
int ret = -1;
qemuDomainMemoryDeviceAlignSize(vm->def, memdef);
@@ -6258,9 +6210,7 @@ qemuDomainDetachMemoryDevice(virQEMUDriverPtr driver,
if (!async)
qemuDomainMarkDeviceForRemoval(vm, &mem->info);
- qemuDomainObjEnterMonitor(driver, vm);
- rc = qemuMonitorDelDevice(priv->mon, mem->info.alias);
- if (qemuDomainObjExitMonitor(driver, vm) < 0 || rc < 0)
+ if (qemuDomainDeleteDevice(vm, mem->info.alias) < 0)
goto cleanup;
if (async) {
@@ -6365,15 +6315,9 @@ qemuDomainHotplugDelVcpu(virQEMUDriverPtr driver,
qemuDomainMarkDeviceAliasForRemoval(vm, vcpupriv->alias);
- qemuDomainObjEnterMonitor(driver, vm);
-
- rc = qemuMonitorDelDevice(qemuDomainGetMonitor(vm), vcpupriv->alias);
-
- if (qemuDomainObjExitMonitor(driver, vm) < 0)
- goto cleanup;
-
- if (rc < 0) {
- virDomainAuditVcpu(vm, oldvcpus, oldvcpus - nvcpus, "update", false);
+ if (qemuDomainDeleteDevice(vm, vcpupriv->alias) < 0) {
+ if (virDomainObjIsActive(vm))
+ virDomainAuditVcpu(vm, oldvcpus, oldvcpus - nvcpus, "update",
false);
goto cleanup;
}
@@ -6943,8 +6887,6 @@ qemuDomainDetachInputDevice(virDomainObjPtr vm,
virDomainInputDefPtr def,
bool async)
{
- qemuDomainObjPrivatePtr priv = vm->privateData;
- virQEMUDriverPtr driver = priv->driver;
virDomainInputDefPtr input;
int ret = -1;
int idx;
@@ -6974,12 +6916,7 @@ qemuDomainDetachInputDevice(virDomainObjPtr vm,
if (!async)
qemuDomainMarkDeviceForRemoval(vm, &input->info);
- qemuDomainObjEnterMonitor(driver, vm);
- if (qemuMonitorDelDevice(priv->mon, input->info.alias) < 0) {
- ignore_value(qemuDomainObjExitMonitor(driver, vm));
- goto cleanup;
- }
- if (qemuDomainObjExitMonitor(driver, vm) < 0)
+ if (qemuDomainDeleteDevice(vm, input->info.alias) < 0)
goto cleanup;
if (async) {
@@ -7001,8 +6938,6 @@ qemuDomainDetachVsockDevice(virDomainObjPtr vm,
virDomainVsockDefPtr dev,
bool async)
{
- qemuDomainObjPrivatePtr priv = vm->privateData;
- virQEMUDriverPtr driver = priv->driver;
virDomainVsockDefPtr vsock = vm->def->vsock;
int ret = -1;
@@ -7017,12 +6952,7 @@ qemuDomainDetachVsockDevice(virDomainObjPtr vm,
if (!async)
qemuDomainMarkDeviceForRemoval(vm, &vsock->info);
- qemuDomainObjEnterMonitor(driver, vm);
- if (qemuMonitorDelDevice(priv->mon, vsock->info.alias) < 0) {
- ignore_value(qemuDomainObjExitMonitor(driver, vm));
- goto cleanup;
- }
- if (qemuDomainObjExitMonitor(driver, vm) < 0)
+ if (qemuDomainDeleteDevice(vm, vsock->info.alias) < 0)
goto cleanup;
if (async) {
--
2.19.2
6:18 a.m.
New subject: [libvirt] [PATCH v3 1/5] qemu_hotplug: Introduce and use qemuDomainDeleteDevice
On Fri, Mar 15, 2019 at 11:23:51 +0100, Michal Privoznik wrote:
The aim of this function will be to fix return value of
qemuMonitorDelDevice() in one specific case. But that is yet to
come. Right now this is nothing but a plain substitution.
Signed-off-by: Michal Privoznik <mprivozn(a)redhat.com>
---
src/qemu/qemu_hotplug.c | 250 +++++++++++++++-------------------------
1 file changed, 90 insertions(+), 160 deletions(-)
ACK
5:23 a.m.
New subject: [libvirt] [PATCH v3 2/5] DO NOT APPLY: Simple reproducer
https://bugzilla.redhat.com/show_bug.cgi?id=1623389
Steps to reproduce:
1) cat shmem.xml
<shmem name='my_shmem0'>
<model type='ivshmem-plain'/>
<size unit='M'>4</size>
<alias name='ua-123'/>
</shmem>
2) virsh attach-device vm1 shmem.xml
3) virsh detach-device-alias vm1 ua-123; virsh detach-device vm1 shmem.xml
4) observe that the device is still in the domain:
virsh dumpxml vm1
<shmem name='my_shmem0'>
<model type='ivshmem-plain'/>
<size unit='M'>4</size>
<alias name='ua-123'/>
<address type='pci' domain='0x0000' bus='0x00'
slot='0x0a' function='0x0'/>
</shmem>
5) But qemu has the device no more:
virsh detach-device-alias vm1 ua-123
error: Failed to detach device with alias ua-123
error: internal error: unable to execute QEMU command 'device_del': Device
'ua-123' not found
This reproducer is to make sure that DELETE_DEVICE event arrives
while monitor is unlocked. It is very hard to time qemu and
libvirt so that the event comes exactly at the time when
detach-device from 3) is doing the monitor call. Simulate this by
unlocking monitor, waiting a few seconds and locking the monitor
again.
Signed-off-by: Michal Privoznik <mprivozn(a)redhat.com>
---
src/qemu/qemu_hotplug.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/src/qemu/qemu_hotplug.c b/src/qemu/qemu_hotplug.c
index 0a3ee2628c..c4a0971a65 100644
--- a/src/qemu/qemu_hotplug.c
+++ b/src/qemu/qemu_hotplug.c
@@ -98,6 +98,11 @@ qemuDomainDeleteDevice(virDomainObjPtr vm,
qemuDomainObjEnterMonitor(driver, vm);
rc = qemuMonitorDelDevice(priv->mon, alias);
+ if (rc < 0) {
+ virObjectUnlock(priv->mon);
+ sleep(10);
+ virObjectLock(priv->mon);
+ }
if (qemuDomainObjExitMonitor(driver, vm) < 0)
rc = -1;
--
2.19.2
5:23 a.m.
New subject: [libvirt] [PATCH v3 3/5] qemuMonitorJSONDelDevice: Return -2 on DeviceNotFound error
A caller might be interested in differentiating the cause for
error, especially if DeviceNotFound error occurred.
Signed-off-by: Michal Privoznik <mprivozn(a)redhat.com>
ACKed-by: Peter Krempa <pkrempa(a)redhat.com>
---
src/qemu/qemu_monitor.c | 10 ++++++++++
src/qemu/qemu_monitor_json.c | 5 +++++
2 files changed, 15 insertions(+)
diff --git a/src/qemu/qemu_monitor.c b/src/qemu/qemu_monitor.c
index 8bd4d4d761..0eb7f60e38 100644
--- a/src/qemu/qemu_monitor.c
+++ b/src/qemu/qemu_monitor.c
@@ -3008,6 +3008,16 @@ qemuMonitorDriveDel(qemuMonitorPtr mon,
}
+/**
+ * @mon: monitor object
+ * @devalias: alias of the device to detach
+ *
+ * Sends device detach request to qemu.
+ *
+ * Returns: 0 on success,
+ * -2 if DeviceNotFound error encountered (error NOT reported)
+ * -1 otherwise (error reported)
+ */
int
qemuMonitorDelDevice(qemuMonitorPtr mon,
const char *devalias)
diff --git a/src/qemu/qemu_monitor_json.c b/src/qemu/qemu_monitor_json.c
index 0236323a51..5c16e1f3a1 100644
--- a/src/qemu/qemu_monitor_json.c
+++ b/src/qemu/qemu_monitor_json.c
@@ -4191,6 +4191,11 @@ int qemuMonitorJSONDelDevice(qemuMonitorPtr mon,
if (qemuMonitorJSONCommand(mon, cmd, &reply) < 0)
goto cleanup;
+ if (qemuMonitorJSONHasError(reply, "DeviceNotFound")) {
+ ret = -2;
+ goto cleanup;
+ }
+
if (qemuMonitorJSONCheckError(cmd, reply) < 0)
goto cleanup;
--
2.19.2
5:23 a.m.
New subject: [libvirt] [PATCH v3 4/5] qemu_hotplug: Fix a rare race condition when detaching a device twice
https://bugzilla.redhat.com/show_bug.cgi?id=1623389
If a device is detached twice from the same domain the following
race condition may happen:
1) The first DetachDevice() call will issue "device_del" on qemu
monitor, but since the DEVICE_DELETED event did not arrive in
time, the API ends claiming "Device detach request sent
successfully".
2) The second DetachDevice() therefore still find the device in
the domain and thus proceeds to detaching it again. It calls
EnterMonitor() and qemuMonitorSend() trying to issue "device_del"
command again. This gets both domain lock and monitor lock
released.
3) At this point, qemu sends us the DEVICE_DELETED event which is
going to be handled by the event loop which ends up calling
qemuDomainSignalDeviceRemoval() to determine who is going to
remove the device from domain definition. Whether it is the
caller that marked the device for removal or whether it is going
to be the event processing thread.
4) Because the device was marked for removal,
qemuDomainSignalDeviceRemoval() returns true, which means the
event is to be processed by the thread that has marked the device
for removal (and is currently still trying to issue "device_del"
command)
5) The thread finally issues the "device_del" command, which
fails (obviously) and therefore it calls
qemuDomainResetDeviceRemoval() to reset the device marking and
quits immediately after, NOT removing any device from the domain
definition.
At this point, the device is still present in the domain
definition but doesn't exist in qemu anymore. Worse, there is no
way to remove it from the domain definition.
Solution is to note down that we've seen the event and if the
second "device_del" fails, not take it as a failure but carry on
with the usual execution.
Signed-off-by: Michal Privoznik <mprivozn(a)redhat.com>
---
src/qemu/qemu_domain.h | 1 +
src/qemu/qemu_hotplug.c | 32 ++++++++++++++++++++++++++++++--
2 files changed, 31 insertions(+), 2 deletions(-)
diff --git a/src/qemu/qemu_domain.h b/src/qemu/qemu_domain.h
index 9f468e5661..fb361515ba 100644
--- a/src/qemu/qemu_domain.h
+++ b/src/qemu/qemu_domain.h
@@ -218,6 +218,7 @@ typedef qemuDomainUnpluggingDevice *qemuDomainUnpluggingDevicePtr;
struct _qemuDomainUnpluggingDevice {
const char *alias;
qemuDomainUnpluggingDeviceStatus status;
+ bool eventSeen; /* True if DEVICE_DELETED event arrived. */
};
diff --git a/src/qemu/qemu_hotplug.c b/src/qemu/qemu_hotplug.c
index c4a0971a65..99abf051bd 100644
--- a/src/qemu/qemu_hotplug.c
+++ b/src/qemu/qemu_hotplug.c
@@ -67,6 +67,9 @@ VIR_LOG_INIT("qemu.qemu_hotplug");
unsigned long long qemuDomainRemoveDeviceWaitTime = 1000ull * 5;
+static void
+qemuDomainResetDeviceRemoval(virDomainObjPtr vm);
+
/**
* qemuDomainDeleteDevice:
* @vm: domain object
@@ -104,8 +107,31 @@ qemuDomainDeleteDevice(virDomainObjPtr vm,
virObjectLock(priv->mon);
}
- if (qemuDomainObjExitMonitor(driver, vm) < 0)
- rc = -1;
+ if (qemuDomainObjExitMonitor(driver, vm) < 0) {
+ /* Domain is no longer running. No cleanup needed. */
+ return -1;
+ }
+
+ if (rc < 0) {
+ /* Deleting device failed. Let's check if DEVICE_DELETED
+ * even arrived. If it did, we need to claim success to
+ * make the caller remove device from domain XML. */
+
+ if (priv->unplug.eventSeen) {
+ /* The event arrived. Return success. */
+ VIR_DEBUG("Detaching of device %s failed, but event arrived",
alias);
+ qemuDomainResetDeviceRemoval(vm);
+ rc = 0;
+ } else if (rc == -2) {
+ /* The device does not exist in qemu, but it still
+ * exists in libvirt. Claim success to make caller
+ * qemuDomainWaitForDeviceRemoval(). Otherwise if
+ * domain XML is queried right after detach API the
+ * device would still be there. */
+ VIR_DEBUG("Detaching of device %s failed and no event arrived",
alias);
+ rc = 0;
+ }
+ }
return rc;
}
@@ -5187,6 +5213,7 @@ qemuDomainResetDeviceRemoval(virDomainObjPtr vm)
{
qemuDomainObjPrivatePtr priv = vm->privateData;
priv->unplug.alias = NULL;
+ priv->unplug.eventSeen = false;
}
/* Returns:
@@ -5246,6 +5273,7 @@ qemuDomainSignalDeviceRemoval(virDomainObjPtr vm,
VIR_DEBUG("Removal of device '%s' continues in waiting thread",
devAlias);
qemuDomainResetDeviceRemoval(vm);
priv->unplug.status = status;
+ priv->unplug.eventSeen = true;
virDomainObjBroadcast(vm);
return true;
}
--
2.19.2
5:46 a.m.
New subject: [libvirt] [PATCH v3 4/5] qemu_hotplug: Fix a rare race condition when detaching a device twice
On Fri, Mar 15, 2019 at 11:23:54 +0100, Michal Privoznik wrote:
https://bugzilla.redhat.com/show_bug.cgi?id=1623389
If a device is detached twice from the same domain the following
race condition may happen:
1) The first DetachDevice() call will issue "device_del" on qemu
monitor, but since the DEVICE_DELETED event did not arrive in
time, the API ends claiming "Device detach request sent
successfully".
2) The second DetachDevice() therefore still find the device in
the domain and thus proceeds to detaching it again. It calls
EnterMonitor() and qemuMonitorSend() trying to issue "device_del"
command again. This gets both domain lock and monitor lock
released.
3) At this point, qemu sends us the DEVICE_DELETED event which is
going to be handled by the event loop which ends up calling
qemuDomainSignalDeviceRemoval() to determine who is going to
remove the device from domain definition. Whether it is the
caller that marked the device for removal or whether it is going
to be the event processing thread.
4) Because the device was marked for removal,
qemuDomainSignalDeviceRemoval() returns true, which means the
event is to be processed by the thread that has marked the device
for removal (and is currently still trying to issue "device_del"
command)
5) The thread finally issues the "device_del" command, which
fails (obviously) and therefore it calls
qemuDomainResetDeviceRemoval() to reset the device marking and
quits immediately after, NOT removing any device from the domain
definition.
At this point, the device is still present in the domain
definition but doesn't exist in qemu anymore. Worse, there is no
way to remove it from the domain definition.
Solution is to note down that we've seen the event and if the
second "device_del" fails, not take it as a failure but carry on
with the usual execution.
Signed-off-by: Michal Privoznik <mprivozn(a)redhat.com>
---
src/qemu/qemu_domain.h | 1 +
src/qemu/qemu_hotplug.c | 32 ++++++++++++++++++++++++++++++--
2 files changed, 31 insertions(+), 2 deletions(-)
ACK
5:23 a.m.
New subject: [libvirt] [PATCH v3 5/5] DO NOT APPLY: Revert simple reproducer
This reverts previous commit.
Signed-off-by: Michal Privoznik <mprivozn(a)redhat.com>
---
src/qemu/qemu_hotplug.c | 5 -----
1 file changed, 5 deletions(-)
diff --git a/src/qemu/qemu_hotplug.c b/src/qemu/qemu_hotplug.c
index 99abf051bd..811fdf6c3a 100644
--- a/src/qemu/qemu_hotplug.c
+++ b/src/qemu/qemu_hotplug.c
@@ -101,11 +101,6 @@ qemuDomainDeleteDevice(virDomainObjPtr vm,
qemuDomainObjEnterMonitor(driver, vm);
rc = qemuMonitorDelDevice(priv->mon, alias);
- if (rc < 0) {
- virObjectUnlock(priv->mon);
- sleep(10);
- virObjectLock(priv->mon);
- }
if (qemuDomainObjExitMonitor(driver, vm) < 0) {
/* Domain is no longer running. No cleanup needed. */
--
2.19.2
2117
days inactive
2117
days old
7 comments
2 participants
participants (2)
-
Michal Privoznik -
Peter Krempa