Messages in this thread | | | Date | Fri, 21 Dec 2007 22:24:28 -0800 | From | Pete Zaitcev <> | Subject | Re: [PATCH 4/4] usb: libusual: locking cleanup |
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On Fri, 21 Dec 2007 00:00:04 -0800, Daniel Walker <dwalker@mvista.com> wrote:
> I converted the usu_init_notify semaphore to normal mutex usage, and it > should still prevent the request_module before the init routine is > complete. Before it acted more like a complete, now the mutex protects > two distinct section from running at the same time..
Let's see.
> @@ -178,10 +179,7 @@ static int usu_probe_thread(void *arg) > int rc; > unsigned long flags; > > - /* A completion does not work here because it's counted. */ > - down(&usu_init_notify); > - up(&usu_init_notify); > - > + mutex_lock(&usu_probe_mutex); > rc = request_module(bias_names[type]);
When I tried it, usb-storage would not load with unresolved symbols. It happens if child (usu_probe_thread) runs ahead of its parent (usb_usual_init -> usb_register -> usu_probe). It's entirely possible, depending on your scheduler.
I hate this down-up trick too, so if you have a better idea, I'm all ears.
-- Pete
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