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@xxxxxxxxxx>
> ---
...
> +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@xxxxxxxxxx>
