On a Tuesday in 2020, Jonathon Jongsma wrote:
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@xxxxxxxxxx>
---
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..a85418e549 100644
--- a/src/node_device/node_device_udev.c
+++ b/src/node_device/node_device_udev.c
@@ -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;
../src/node_device/node_device_udev.c:1980:26: error: unused variable 'dirinfo' [-Werror,-Wunused-variable]
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;
s/bail/error/
+ }
+
+ 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);
When returning an error code, any libvirt function should either report
an error in all cases or stay quiet, so something like:
error ? error->message : _("unknown error")
is a tiny bit frendlier for debugging.
+
+ 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;
../src/node_device/node_device_udev.c:2033:23: error: unused variable 'error' [-Werror,-Wunused-variable]
g_autoptr(GError) error = NULL;
^
Jano
+ 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. */
--
2.26.2
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