[PATCH v3 05/12] qemu: handle host usb device add/del udev events

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Now when code handling attaching/detaching usb hostdev is appropriately
changed use it to handle host usb device udev add/del events.

As device adding/deleting needs acquiring job condition it is done in
thread pool rather in event loop thread itself where udev events are
delivered. However implementation in this patch is a bit different from
other places as we instead of finding right domain in event loop thread
and creating a single thread pool job create job for every vm. Such
a strategy allows us to avoid taking domain lock in event loop thread so
we have little chances to block event loop thread because some API
handler grabs domain lock for a significant amount of time.

Signed-off-by: Nikolay Shirokovskiy <nshirokovskiy@xxxxxxxxxxxxx>
---
 src/qemu/Makefile.inc.am |   2 +
 src/qemu/qemu_conf.h     |   3 +
 src/qemu/qemu_domain.c   |   2 +
 src/qemu/qemu_domain.h   |   2 +
 src/qemu/qemu_driver.c   | 324 ++++++++++++++++++++++++++++++++++++++-
 5 files changed, 332 insertions(+), 1 deletion(-)

diff --git a/src/qemu/Makefile.inc.am b/src/qemu/Makefile.inc.am
index 48fd0332ec..26a686e56f 100644
--- a/src/qemu/Makefile.inc.am
+++ b/src/qemu/Makefile.inc.am
@@ -89,6 +89,7 @@ libvirt_driver_qemu_impl_la_CFLAGS = \
 	-I$(srcdir)/conf \
 	-I$(srcdir)/secret \
 	$(AM_CFLAGS) \
+	$(UDEV_CFLAGS) \
 	$(NULL)
 libvirt_driver_qemu_impl_la_LDFLAGS = $(AM_LDFLAGS)
 libvirt_driver_qemu_impl_la_LIBADD = \
@@ -97,6 +98,7 @@ libvirt_driver_qemu_impl_la_LIBADD = \
 	$(LIBNL_LIBS) \
 	$(SELINUX_LIBS) \
 	$(LIBXML_LIBS) \
+	$(UDEV_LIBS) \
 	$(NULL)
 libvirt_driver_qemu_impl_la_SOURCES = $(QEMU_DRIVER_SOURCES)
 
diff --git a/src/qemu/qemu_conf.h b/src/qemu/qemu_conf.h
index 8473d6d4ca..f78ebcd829 100644
--- a/src/qemu/qemu_conf.h
+++ b/src/qemu/qemu_conf.h
@@ -296,6 +296,9 @@ struct _virQEMUDriver {
 
     /* Immutable pointer, self-locking APIs */
     virHashAtomicPtr migrationErrors;
+
+    struct udev_monitor *udev_monitor;
+    int udev_watch;
 };
 
 virQEMUDriverConfigPtr virQEMUDriverConfigNew(bool privileged);
diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
index ad4db7e881..711f562754 100644
--- a/src/qemu/qemu_domain.c
+++ b/src/qemu/qemu_domain.c
@@ -15401,6 +15401,8 @@ qemuProcessEventFree(struct qemuProcessEvent *event)
     case QEMU_PROCESS_EVENT_SERIAL_CHANGED:
     case QEMU_PROCESS_EVENT_BLOCK_JOB:
     case QEMU_PROCESS_EVENT_MONITOR_EOF:
+    case QEMU_PROCESS_EVENT_USB_REMOVED:
+    case QEMU_PROCESS_EVENT_USB_ADDED:
         VIR_FREE(event->data);
         break;
     case QEMU_PROCESS_EVENT_JOB_STATUS_CHANGE:
diff --git a/src/qemu/qemu_domain.h b/src/qemu/qemu_domain.h
index f53ea146e1..abd717c025 100644
--- a/src/qemu/qemu_domain.h
+++ b/src/qemu/qemu_domain.h
@@ -537,6 +537,8 @@ typedef enum {
     QEMU_PROCESS_EVENT_MONITOR_EOF,
     QEMU_PROCESS_EVENT_PR_DISCONNECT,
     QEMU_PROCESS_EVENT_RDMA_GID_STATUS_CHANGED,
+    QEMU_PROCESS_EVENT_USB_REMOVED,
+    QEMU_PROCESS_EVENT_USB_ADDED,
 
     QEMU_PROCESS_EVENT_LAST
 } qemuProcessEventType;
diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
index c208591133..51f1d5d4a2 100644
--- a/src/qemu/qemu_driver.c
+++ b/src/qemu/qemu_driver.c
@@ -34,6 +34,7 @@
 #include <sys/ioctl.h>
 #include <sys/un.h>
 #include <byteswap.h>
+#include <libudev.h>
 
 
 #include "qemu_driver.h"
@@ -719,6 +720,221 @@ qemuDomainFindMaxID(virDomainObjPtr vm,
 }
 
 
+struct qemuUdevUSBRemoveData {
+    unsigned int bus;
+    unsigned int device;
+};
+
+struct qemuUdevUSBAddData {
+    unsigned int vendor;
+    unsigned int product;
+};
+
+struct qemuUdevUSBEventData {
+    union {
+        struct qemuUdevUSBRemoveData remove;
+        struct qemuUdevUSBAddData add;
+    } data;
+    bool remove;
+};
+
+static int
+qemuUdevUSBHandleEvent(virDomainObjPtr vm, void *opaque)
+{
+    struct qemuUdevUSBEventData *data = opaque;
+    struct qemuProcessEvent *event = NULL;
+
+    if (VIR_ALLOC(event) < 0)
+        return 0;
+
+    if (data->remove) {
+        struct qemuUdevUSBRemoveData *rm_data;
+
+
+        if (VIR_ALLOC(rm_data) < 0)
+            goto cleanup;
+
+        *rm_data = data->data.remove;
+        event->data = rm_data;
+        event->eventType = QEMU_PROCESS_EVENT_USB_REMOVED;
+    } else {
+        struct qemuUdevUSBAddData *add_data;
+
+        if (VIR_ALLOC(add_data) < 0)
+            goto cleanup;
+
+        *add_data = data->data.add;
+        event->data = add_data;
+        event->eventType = QEMU_PROCESS_EVENT_USB_ADDED;
+    }
+
+    event->vm = virObjectRef(vm);
+
+    if (virThreadPoolSendJob(qemu_driver->workerPool, 0, event) < 0) {
+        virObjectUnref(vm);
+        goto cleanup;
+    }
+
+    event = NULL;
+
+ cleanup:
+    qemuProcessEventFree(event);
+
+    return 0;
+}
+
+
+static void
+qemuUdevEventHandleCallback(int watch ATTRIBUTE_UNUSED,
+                            int fd ATTRIBUTE_UNUSED,
+                            int events ATTRIBUTE_UNUSED,
+                            void *data ATTRIBUTE_UNUSED)
+{
+    struct qemuUdevUSBEventData event_data;
+    struct udev_device *dev = NULL;
+    const char *action;
+    const char *devtype;
+    const char *tmp;
+
+    /* libvirtd daemon do not run event loop before full state drivers
+     * initialization. Also state drivers uninitialized only after
+     * full stop of event loop. In short driver initialization/uninitialization
+     * and handling events occurs in same main loop thread. Thus we
+     * don't need any locking here. */
+
+    if (!(dev = udev_monitor_receive_device(qemu_driver->udev_monitor))) {
+        VIR_WARNINGS_NO_WLOGICALOP_EQUAL_EXPR
+        if (errno == EAGAIN || errno == EWOULDBLOCK) {
+        VIR_WARNINGS_RESET
+            return;
+        }
+
+        virReportSystemError(errno, "%s",
+                             _("failed to receive device from udev monitor"));
+        return;
+    }
+
+    devtype = udev_device_get_devtype(dev);
+
+    if (STRNEQ_NULLABLE(devtype, "usb_device"))
+        goto cleanup;
+
+    if (!(action = udev_device_get_action(dev))) {
+        virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                       _("failed to receive action from udev monitor"));
+        goto cleanup;
+    }
+
+    if (STREQ(action, "remove")) {
+        struct qemuUdevUSBRemoveData *rm_data = &event_data.data.remove;
+
+        if (!(tmp = udev_device_get_property_value(dev, "BUSNUM"))) {
+            virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                           _("failed to receive busnum from udev monitor"));
+            goto cleanup;
+        }
+        if (virStrToLong_ui(tmp, NULL, 10, &rm_data->bus) < 0) {
+            virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                           _("Failed to convert busnum to int"));
+            goto cleanup;
+        }
+
+        if (!(tmp = udev_device_get_property_value(dev, "DEVNUM"))) {
+            virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                           _("failed to receive devnum from udev monitor"));
+            goto cleanup;
+        }
+        if (virStrToLong_ui(tmp, NULL, 10, &rm_data->device) < 0) {
+            virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                           _("Failed to convert devnum to int"));
+            goto cleanup;
+        }
+        event_data.remove = true;
+    } else if (STREQ(action, "add")) {
+        struct qemuUdevUSBAddData *add_data = &event_data.data.add;
+
+        if (!(tmp = udev_device_get_property_value(dev, "ID_VENDOR_ID"))) {
+            virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                           _("failed to receive vendor from udev monitor"));
+            goto cleanup;
+        }
+        if (virStrToLong_ui(tmp, NULL, 16, &add_data->vendor) < 0) {
+            virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                           _("Failed to convert vendor to int"));
+            goto cleanup;
+        }
+
+        if (!(tmp = udev_device_get_property_value(dev, "ID_MODEL_ID"))) {
+            virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                           _("failed to receive product from udev monitor"));
+            goto cleanup;
+        }
+        if (virStrToLong_ui(tmp, NULL, 16, &add_data->product) < 0) {
+            virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                           _("Failed to convert product to int"));
+            goto cleanup;
+        }
+        event_data.remove = false;
+    } else {
+        goto cleanup;
+    }
+
+    virDomainObjListForEach(qemu_driver->domains, false, qemuUdevUSBHandleEvent, &event_data);
+
+ cleanup:
+    udev_device_unref(dev);
+}
+
+
+static int
+qemuUdevInitialize(void)
+{
+    struct udev *udev;
+
+    if (!(udev = udev_new())) {
+        virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                       _("failed to create udev context"));
+        return -1;
+    }
+
+    if (!(qemu_driver->udev_monitor = udev_monitor_new_from_netlink(udev, "udev"))) {
+        udev_unref(udev);
+        virReportError(VIR_ERR_INTERNAL_ERROR, "%s",
+                       _("udev_monitor_new_from_netlink returned NULL"));
+        return -1;
+    }
+
+    udev_monitor_enable_receiving(qemu_driver->udev_monitor);
+
+    qemu_driver->udev_watch = virEventAddHandle(udev_monitor_get_fd(qemu_driver->udev_monitor),
+                                                VIR_EVENT_HANDLE_READABLE,
+                                                qemuUdevEventHandleCallback, NULL, NULL);
+
+    if (qemu_driver->udev_watch < 0)
+        return -1;
+
+    return 0;
+}
+
+
+static void
+qemuUdevCleanup(void)
+{
+    if (qemu_driver->udev_monitor) {
+        struct udev *udev = udev_monitor_get_udev(qemu_driver->udev_monitor);
+
+        udev_monitor_unref(qemu_driver->udev_monitor);
+        udev_unref(udev);
+        qemu_driver->udev_monitor = NULL;
+    }
+
+    if (qemu_driver->udev_watch > 0) {
+        virEventRemoveHandle(qemu_driver->udev_watch);
+        qemu_driver->udev_watch = 0;
+    }
+}
+
+
 /**
  * qemuStateInitialize:
  *
@@ -1042,6 +1258,9 @@ qemuStateInitialize(bool privileged,
     if (!(qemu_driver->closeCallbacks = virCloseCallbacksNew()))
         goto error;
 
+    if (qemuUdevInitialize() < 0)
+        goto error;
+
     /* Get all the running persistent or transient configs first */
     if (virDomainObjListLoadAllConfigs(qemu_driver->domains,
                                        cfg->stateDir,
@@ -1256,6 +1475,8 @@ qemuStateCleanup(void)
 
     virLockManagerPluginUnref(qemu_driver->lockManager);
 
+    qemuUdevCleanup();
+
     virMutexDestroy(&qemu_driver->lock);
     VIR_FREE(qemu_driver);
 
@@ -5028,7 +5249,102 @@ processRdmaGidStatusChangedEvent(virDomainObjPtr vm,
 }
 
 
-static void qemuProcessEventHandler(void *data, void *opaque)
+static void
+processUSBAddedEvent(virQEMUDriverPtr driver,
+                     virDomainObjPtr vm,
+                     struct qemuUdevUSBAddData *data)
+{
+    virDomainHostdevDefPtr hostdev;
+    virDomainHostdevSubsysUSBPtr usbsrc;
+    size_t i;
+
+    if (qemuDomainObjBeginJob(driver, vm, QEMU_JOB_MODIFY) < 0)
+        return;
+
+    if (!virDomainObjIsActive(vm)) {
+        VIR_DEBUG("Domain is not running");
+        goto cleanup;
+    }
+
+    for (i = 0; i < vm->def->nhostdevs; i++) {
+        hostdev = vm->def->hostdevs[i];
+
+        if (hostdev->source.subsys.type != VIR_DOMAIN_HOSTDEV_SUBSYS_TYPE_USB)
+            continue;
+
+        usbsrc = &hostdev->source.subsys.u.usb;
+
+        if (!usbsrc->replug)
+            continue;
+
+        if (usbsrc->vendor == data->vendor && usbsrc->product == data->product)
+            break;
+    }
+
+    if (i == vm->def->nhostdevs)
+        goto cleanup;
+
+    if (qemuDomainAttachHostDevice(driver, vm, hostdev) < 0)
+        goto cleanup;
+
+ cleanup:
+    qemuDomainObjEndJob(driver, vm);
+}
+
+
+static void
+processUSBRemovedEvent(virQEMUDriverPtr driver,
+                       virDomainObjPtr vm,
+                       struct qemuUdevUSBRemoveData *data)
+{
+    size_t i;
+    virDomainHostdevDefPtr hostdev;
+    virDomainDeviceDef dev = { .type = VIR_DOMAIN_DEVICE_HOSTDEV };
+
+    if (qemuDomainObjBeginJob(driver, vm, QEMU_JOB_MODIFY) < 0)
+        return;
+
+    if (!virDomainObjIsActive(vm)) {
+        VIR_DEBUG("Domain is not running");
+        goto cleanup;
+    }
+
+    for (i = 0; i < vm->def->nhostdevs; i++) {
+        virDomainHostdevSubsysUSBPtr usbsrc;
+
+        hostdev = vm->def->hostdevs[i];
+        if (hostdev->source.subsys.type != VIR_DOMAIN_HOSTDEV_SUBSYS_TYPE_USB)
+            continue;
+
+        usbsrc = &hostdev->source.subsys.u.usb;
+
+        if (!usbsrc->replug)
+            continue;
+
+        /* don't mess with devices that don't use stable host addressing
+         * with respect to unplug/plug to host
+         */
+        if (!usbsrc->vendor || !usbsrc->product)
+            continue;
+
+        if (usbsrc->bus == data->bus && usbsrc->device == data->device)
+            break;
+    }
+
+    if (i == vm->def->nhostdevs)
+        goto cleanup;
+
+    dev.data.hostdev = hostdev;
+    if (qemuDomainDetachDeviceLive(vm, &dev, driver, true, true) < 0)
+        goto cleanup;
+
+ cleanup:
+    qemuDomainObjEndJob(driver, vm);
+}
+
+
+static void
+qemuProcessEventHandler(void *data, void *opaque)
 {
     struct qemuProcessEvent *processEvent = data;
     virDomainObjPtr vm = processEvent->vm;
@@ -5074,6 +5390,12 @@ static void qemuProcessEventHandler(void *data, void *opaque)
     case QEMU_PROCESS_EVENT_RDMA_GID_STATUS_CHANGED:
         processRdmaGidStatusChangedEvent(vm, processEvent->data);
         break;
+    case QEMU_PROCESS_EVENT_USB_REMOVED:
+        processUSBRemovedEvent(driver, vm, processEvent->data);
+        break;
+    case QEMU_PROCESS_EVENT_USB_ADDED:
+        processUSBAddedEvent(driver, vm, processEvent->data);
+        break;
     case QEMU_PROCESS_EVENT_LAST:
         break;
     }
-- 
2.23.0

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