On Fri, Mar 26, 2021 at 11:48:10AM -0500, Jonathon Jongsma wrote:
We need to query mdevctl for changes to device definitions since an administrator can define new devices by executing mdevctl outside of libvirt.
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 directory for changes to files. When a change is detected, we query mdevctl and update our device list. The mdevctl querying is handled in a throwaway thread, and these threads are synchronized with a mutex.
Signed-off-by: Jonathon Jongsma <jjongsma@redhat.com> --- ...
+static void +mdevctlEventHandleCallback(GFileMonitor *monitor G_GNUC_UNUSED, + GFile *file, + GFile *other_file G_GNUC_UNUSED, + GFileMonitorEvent event_type, + gpointer user_data) +{ + udevEventData *priv = user_data; + /* if a new directory appears, monitor that directory for changes */ + if (event_type == G_FILE_MONITOR_EVENT_CREATED && + g_file_query_file_type(file, G_FILE_QUERY_INFO_NONE, NULL) == + G_FILE_TYPE_DIRECTORY) {
^probably better written as: if (event_type == G_FILE_MONITOR_EVENT_CREATED) { file_type = g_file_query_file_type(file, G_FILE_QUERY_INFO_NONE, NULL); if (file_type == G_FILE_TYPE_DIRECTORY) { ... } }
+ GList *newmonitors = monitorFileRecursively(priv, file);
newline here for better optical code separation
+ virMutexLock(&priv->mdevctlLock); + priv->mdevctlMonitors = g_list_concat(priv->mdevctlMonitors, newmonitors); + virMutexUnlock(&priv->mdevctlLock); + } + + /* When mdevctl creates a device, it can result in multiple notify events + * emitted for a single logical change (e.g. several CHANGED events, or a + * CREATED and CHANGED event followed by CHANGES_DONE_HINT). To avoid + * spawning a mdevctl thread multiple times for a single logical + * 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_CHANGES_DONE_HINT) { + if (priv->mdevctlTimeout > 0) + virEventRemoveTimeout(priv->mdevctlTimeout); + priv->mdevctlTimeout = virEventAddTimeout(100, scheduleMdevctlHandler, + priv, NULL); + return; + } + + scheduleMdevctlHandler(-1, priv); +}
Reviewed-by: Erik Skultety <eskultet@redhat.com>