On Wed, Nov 18, 2009 at 8:35 AM, Alan Stern <stern@xxxxxxxxxxxxxxxxxxx> wrote: > On Wed, 18 Nov 2009, Oliver Neukum wrote: > >> Am Mittwoch, 18. November 2009 11:41:25 schrieb Jiri Kosina: >> > > User space receives the hotplug event for the class device, makes the >> > > device node and notifies another program that opens the device node. >> > > The program opens the device node which calls into usb_open and then >> > > skel_open. skel_open calls usb_find_interface. usb_find_interfaces >> > > searches the klist_devices of skel_driver, finds no device associated >> > > with the minor number and returns NULL. skel_open returns -ENODEV. >> > > >> > > Control returns to really_probe and really_probe calls driver_bound >> > > which adds the device to the list of devices associated with >> > > skel_driver (klist_devices). >> > > >> > > I'm not sure what the right way to solve this is. A call to >> > > wait_for_device_probe() in the skel_open call before calling >> > > usb_find_interface fixes the problem, but it is a rather large hammer. >> > >> >> Device core code is hard to follow, but I tried. >> How about simply covering all of usb_register_dev() with minor_rwsem? > > That won't help. The window is between the end of usb_register_dev() > and the end of skel_probe(), during which time the mutex isn't held. > Like I said above, the window goes all the way till the device gets added to the klist_devices on the driver. -- 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
