Hello Alan, On Tue, Jan 20, 2015 at 10:26:30AM -0500, Alan Stern wrote: > On Tue, 20 Jan 2015, Olivier Sobrie wrote: > > > When usb_queue_reset() is called it schedules a work in view of > > resetting the usb interface. When the reset work is running, it > > can be scheduled again (e.g. by the usb disconnect method of > > the driver). > > > > Consider that the reset work is queued again while the reset work > > is running and that this work leads to a forced unbinding of the > > usb interface (e.g. because a driver is bound to the interface > > and has no pre/post_reset methods - see usb_reset_device()). > > In such condition, usb_unbind_interface() gets called and this > > function calls usb_cancel_queued_reset() which does nothing > > because the flag "reset_running" is set to 1. The second reset > > work that has been scheduled is therefore not cancelled. > > Later, the usb_reset_device() tries to rebind the interface. > > If it fails, then the usb interface context which contain the > > reset work struct is freed and it most likely crash when the > > second reset work tries to be run. > > There was an earlier patch posted for testing (no results yet) > affecting this same region of code: > > http://marc.info/?l=linux-usb&m=142064533924019&w=2 > > It should fix the problem described here, because (among other things) > it adds usb_get/put_intf calls to the delayed-reset routines. I tested your patch. It also fixes the problem I observed. You can drop mine. For your info: My test consists in powering down a usb hso modem while one of its serial port is opened. It leads to two URB failures, each urb callback queues a reset. Without your fix (or without the one I sent), a crash happens after less than ~20 power up/down sequences. With your fix, after more than 1000 power up/down I don't see any crash. Thanks, -- Olivier -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
