[lkml]   [2003]   [Dec]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [linux-usb-devel] Re: [OOPS, usbcore, releaseintf] 2.6.0-test10-mm1
> Here's how I see it.
> dev->serialize is meant to protect significant state changes, things like
> set_configuration and device disconnect. ps->devsem is meant to protect
> against usbfs trying to do two things to the device at the same time.

Actually no: it is a read lock and all routines take it with down_read except
for the disconnect routine. So it is only there to guard against disconnect.

> But you also want to protect against usbfs using the device during a state
> change. (The normal protection mechanisms don't work because usbfs might
> be using a device without having a driver bound to any of its interfaces.)
> Given that, there's no reason usbfs shouldn't just use serialize instead
> of devsem.
> The fact that the core calls driver_disconnect with serialize already held
> then just makes your life simpler: You don't need to acquire the lock
> yourself!
> The only tricky part is that you have to release serialize (which now is
> your only lock) before calling set_configuration. But as you said, you
> would have to release ps->devsem anyway, so nothing's lost there.
> Anything wrong with this approach?

Nothing - that is exactly what my patch does. And it works... except
for the Oops in usb_put_dev.

All the best,

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

 \ /
  Last update: 2005-03-22 13:59    [W:0.218 / U:0.040 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site