On Thu, 15 Jan 2009 16:16:19 -0800 (PST) Frederic Weisbecker <fweisbec@xxxxxxxxx> wrote: > While looking at the workqueue tracer, I noticed that kpsmoused receives > rarely (if not never) events. > > Currently, when a mouse has to resync, it uses the kpsmoused singlethreaded > workqueue. But recync are rare. While reading an old discussion, it seems > that usual workqueue events can't be used for that purpose because resync > can take too much time and could delay the other works in queue. > > But if you have built psmouse driver, this workqueue will always be present > whether you have a ps/2 port or not. And its events are rare. > > To avoid this pointless task, this patch makes the kpsmoused a kernel > thread only created on the fly when a recync is needed. Once the recync is done, > this thread will die. So you will almost never see it, and it will not be > an inactive task anymore. > > This thread is created through a usual workqueue event (because we can't create > it from interrupt). > Seems like a reasonable objective. > > ... > > /* > * __psmouse_set_state() sets new psmouse state and resets all flags. > @@ -313,7 +307,8 @@ static irqreturn_t psmouse_interrupt(struct serio *serio, > psmouse->name, psmouse->phys, psmouse->pktcnt); > psmouse->badbyte = psmouse->packet[0]; > __psmouse_set_state(psmouse, PSMOUSE_RESYNCING); > - psmouse_queue_work(psmouse, &psmouse->resync_work, 0); > + atomic_inc(&psmouse->nb_recync_pending); The patch and the changelog consistently misspell "sync". A code comment (in psmouse.h) which clearly spells out the role of nb_recync_pending would be useful. > + schedule_work(&psmouse->resync_work); > goto out; > } > > > ... > > @@ -1131,7 +1155,13 @@ static void psmouse_disconnect(struct serio *serio) > > /* make sure we don't have a resync in progress */ > mutex_unlock(&psmouse_mutex); > - flush_workqueue(kpsmoused_wq); > + > + prepare_to_wait(&psmouse->recync_pending_queue, &wait, > + TASK_UNINTERRUPTIBLE); > + if (atomic_read(&psmouse->nb_recync_pending)) > + schedule(); > + finish_wait(&psmouse->recync_pending_queue, &wait); So... we're requiring that nb_recync_pending is zero at this stage? I wonder if the code manages to do that. A little WARN_ON(), maybe? > mutex_lock(&psmouse_mutex); > -- To unsubscribe from this list: send the line "unsubscribe linux-input" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
