[libvirt PATCH 09/16] nodedev: add an mdevctl thread
Jonathon Jongsma
jjongsma at redhat.com
Thu Jul 16 22:21:39 UTC 2020
We need to peridocally query mdevctl for changes to device definitions
since an administrator can define new devices with mdevctl outside of
libvirt.
In order to do this, a new thread is created to handle the querying. In
the future, mdevctl may add a way to signal device add / remove via
events, but for now we resort to a bit of a workaround: monitoring the
mdevctl config directories for changes to files. When a change is
detected, we query mdevctl and update our device list.
Signed-off-by: Jonathon Jongsma <jjongsma at redhat.com>
---
src/node_device/node_device_udev.c | 182 +++++++++++++++++++++++++++++
1 file changed, 182 insertions(+)
diff --git a/src/node_device/node_device_udev.c b/src/node_device/node_device_udev.c
index e06584a3dc..02017b5325 100644
--- a/src/node_device/node_device_udev.c
+++ b/src/node_device/node_device_udev.c
@@ -41,6 +41,7 @@
#include "virnetdev.h"
#include "virmdev.h"
#include "virutil.h"
+#include <gio/gio.h>
#include "configmake.h"
@@ -66,6 +67,11 @@ struct _udevEventData {
virCond threadCond;
bool threadQuit;
bool dataReady;
+
+ virThread mdevctlThread;
+ virCond mdevctlCond;
+ bool mdevctlReady;
+ GList *mdevctl_monitors;
};
static virClassPtr udevEventDataClass;
@@ -85,8 +91,10 @@ udevEventDataDispose(void *obj)
udev = udev_monitor_get_udev(priv->udev_monitor);
udev_monitor_unref(priv->udev_monitor);
udev_unref(udev);
+ g_list_free_full(priv->mdevctl_monitors, g_object_unref);
virCondDestroy(&priv->threadCond);
+ virCondDestroy(&priv->mdevctlCond);
}
@@ -117,6 +125,11 @@ udevEventDataNew(void)
return NULL;
}
+ if (virCondInit(&ret->mdevctlCond) < 0) {
+ virObjectUnref(ret);
+ return NULL;
+ }
+
ret->watch = -1;
return ret;
}
@@ -1520,6 +1533,7 @@ nodeStateCleanup(void)
virObjectLock(priv);
priv->threadQuit = true;
virCondSignal(&priv->threadCond);
+ virCondSignal(&priv->mdevctlCond);
virObjectUnlock(priv);
virThreadJoin(&priv->th);
}
@@ -1601,6 +1615,40 @@ udevEventMonitorSanityCheck(udevEventDataPtr priv,
}
+/* Thread to query mdevctl for the current state of persistent mediated device
+ * defintions when any changes are detected */
+static
+void mdevctlThread(void *opaque G_GNUC_UNUSED)
+{
+ udevEventDataPtr priv = driver->privateData;
+
+ while (1) {
+ virObjectLock(priv);
+ while (!priv->mdevctlReady && !priv->threadQuit) {
+ if (virCondWait(&priv->mdevctlCond, &priv->parent.lock)) {
+ virReportSystemError(errno, "%s",
+ _("handler failed to wait on condition"));
+ virObjectUnlock(priv);
+ return;
+ }
+ }
+
+ if (priv->threadQuit) {
+ virObjectUnlock(priv);
+ return;
+ }
+
+ virObjectUnlock(priv);
+
+ mdevctlEnumerateDevices();
+
+ virObjectLock(priv);
+ priv->mdevctlReady = false;
+ virObjectUnlock(priv);
+ }
+}
+
+
/**
* udevEventHandleThread
* @opaque: unused
@@ -1708,6 +1756,69 @@ udevEventHandleCallback(int watch G_GNUC_UNUSED,
}
+static int timeout_id = 0;
+
+static gboolean
+signalMdevctlThread(void *user_data)
+{
+ udevEventDataPtr priv = user_data;
+
+ if (timeout_id) {
+ g_source_remove(timeout_id);
+ timeout_id = 0;
+ }
+
+ virObjectLock(priv);
+ priv->mdevctlReady = true;
+ virCondSignal(&priv->mdevctlCond);
+ virObjectUnlock(priv);
+
+ return G_SOURCE_REMOVE;
+}
+
+
+static void
+mdevctlEventHandleCallback(GFileMonitor *monitor G_GNUC_UNUSED,
+ GFile *file,
+ GFile *other_file G_GNUC_UNUSED,
+ GFileMonitorEvent event_type,
+ gpointer user_data)
+{
+ udevEventDataPtr priv = user_data;
+
+ /* if a new directory appears, monitor that directory for changes */
+ if (g_file_query_file_type(file, G_FILE_QUERY_INFO_NONE, NULL) ==
+ G_FILE_TYPE_DIRECTORY) {
+ GFileMonitor *mon;
+
+ if ((mon = g_file_monitor(file, G_FILE_MONITOR_NONE, NULL, NULL))) {
+ g_signal_connect(mon, "changed",
+ G_CALLBACK(mdevctlEventHandleCallback),
+ user_data);
+ virObjectLock(priv);
+ priv->mdevctl_monitors = g_list_append(priv->mdevctl_monitors, mon);
+ virObjectUnlock(priv);
+ }
+ }
+
+ /* Sometimes a single configuration change results in multiple notify
+ * events (e.g. several CHANGED events, or a CREATED and CHANGED event
+ * followed by CHANGES_DONE_HINT). To avoid triggering the mdevctl thread
+ * multiple times for a single configuration change, try to coalesce these
+ * changes by waiting for the CHANGES_DONE_HINT event. As a fallback, add
+ * a timeout to trigger the signal if that event never comes */
+ if (event_type == G_FILE_MONITOR_EVENT_CREATED ||
+ event_type == G_FILE_MONITOR_EVENT_CHANGED) {
+ if (timeout_id)
+ g_source_remove(timeout_id);
+ timeout_id = g_timeout_add(100, signalMdevctlThread, priv);
+ return;
+ }
+
+ signalMdevctlThread(priv);
+}
+
+
/* DMI is intel-compatible specific */
#if defined(__x86_64__) || defined(__i386__) || defined(__amd64__)
static void
@@ -1858,6 +1969,58 @@ udevPCITranslateInit(bool privileged G_GNUC_UNUSED)
}
+/* Recursively monitors dir and any subdirectory for file changes and returns a
+ * GList of GFileMonitor objects */
+static GList*
+monitorDirRecursively(GFile *dir,
+ GCallback changed_cb,
+ gpointer user_data)
+{
+ GList *monitors = NULL;
+ g_autoptr(GFileInfo) dirinfo = NULL;
+ g_autoptr(GError) error = NULL;
+ g_autoptr(GFileEnumerator) children = NULL;
+ GFileMonitor *mon;
+
+ if (!(children = g_file_enumerate_children(dir, "standard::*",
+ G_FILE_QUERY_INFO_NONE, NULL, &error))) {
+ if (error->code == G_IO_ERROR_NOT_DIRECTORY)
+ return NULL;
+ goto bail;
+ }
+
+ if (!(mon = g_file_monitor(dir, G_FILE_MONITOR_NONE, NULL, &error)))
+ goto bail;
+
+ g_signal_connect(mon, "changed", changed_cb, user_data);
+ monitors = g_list_append(monitors, mon);
+
+ while (true) {
+ GFileInfo *info;
+ GFile *child;
+ GList *child_monitors = NULL;
+
+ if (!g_file_enumerator_iterate(children, &info, &child, NULL, &error))
+ goto bail;
+ if (!info)
+ break;
+
+ child_monitors = monitorDirRecursively(child, changed_cb, user_data);
+ if (child_monitors)
+ monitors = g_list_concat(monitors, child_monitors);
+ }
+
+ return monitors;
+
+ bail:
+ if (error)
+ virReportError(VIR_ERR_INTERNAL_ERROR,
+ _("Unable to monitor directory: %s"), error->message);
+
+ g_list_free_full(monitors, g_object_unref);
+ return NULL;
+}
+
static int
nodeStateInitialize(bool privileged,
const char *root,
@@ -1867,6 +2030,8 @@ nodeStateInitialize(bool privileged,
udevEventDataPtr priv = NULL;
struct udev *udev = NULL;
virThread enumThread;
+ g_autoptr(GError) error = NULL;
+ g_autoptr(GFile) mdevctlConfigDir = g_file_new_for_path("/etc/mdevctl.d");
if (root != NULL) {
virReportError(VIR_ERR_INVALID_ARG, "%s",
@@ -1969,6 +2134,23 @@ nodeStateInitialize(bool privileged,
if (priv->watch == -1)
goto unlock;
+ if (virThreadCreateFull(&priv->mdevctlThread, true, mdevctlThread,
+ "mdevctl-event", false, NULL) < 0) {
+ virReportSystemError(errno, "%s",
+ _("failed to create mdevctl handler thread"));
+ goto unlock;
+ }
+
+ /* mdevctl may add notification events in the future:
+ * https://github.com/mdevctl/mdevctl/issues/27. For now, fall back to
+ * monitoring the mdevctl configuration directory for changes.
+ * mdevctl configuration is stored in a directory tree within
+ * /etc/mdevctl.d/. There is a directory for each parent device, which
+ * contains a file defining each mediated device */
+ priv->mdevctl_monitors = monitorDirRecursively(mdevctlConfigDir,
+ G_CALLBACK(mdevctlEventHandleCallback),
+ priv);
+
virObjectUnlock(priv);
/* Create a fictional 'computer' device to root the device tree. */
--
2.21.3
More information about the libvir-list
mailing list