Re: [libvirt PATCH v6 14/30] nodedev: Refresh mdev devices when changes are detected

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(a)redhat.com&gt; ---

+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) {

+ GList *newmonitors = monitorFileRecursively(priv, file);

+ 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); +}