On Wed, 19 Feb 2003, David Brownell wrote: > That assumes an incorrectly written disconnect() routine. And > the two changes identified (did you notice that SCSI hot-unplug > discussion identified _exactly the same_ two changes??) would > prevent that happening: (a) no more submissions are possible, > (b) something nukes all pending urbs. > > For (b) there are several options. Today we expect (b1) device > driver handles all in disconnect(), except that to guard against > bugs there sometimes (b2) HCD may need to get involved. I'd > think a cleaner solution would be (b3) usbcore kills them all; > less work for device drivers too.
It sounds to me like this is really a question of how far do you want to trust device drivers. AFAIK, there is nothing at all to prevent a driver from submitting an urb for a totally different device (i.e., one that it isn't controlling), never mind submitting an urb for an interface after disconnect()-ing. In fact, usb_submit_urb() doesn't even know which driver called it. Now I admit, the first of these is much less likely than the second. But the fact remains, you have to decide how much responsibility you want to leave to the driver and how much to assume in the core. Part of the current problem may be that the rules are not clearly stated -- I wouldn't know about that. My personal feeling is that basically drivers should be trusted to do what's right (and fixed when they don't). The core should do just enough checking to make sure that a badly-behaving driver can't crash the kernel. Depending on how the HCD's are written, (a) may or may not be necessary, although it probably wouldn't hurt in any case. (b) is a different story, and is considerably complicated by the need to take into account module unloading, port resets, configuration and altsetting changes, in addition to physical disconnects. Alan Stern ------------------------------------------------------- This SF.net email is sponsored by: SlickEdit Inc. Develop an edge. The most comprehensive and flexible code editor you can use. Code faster. C/C++, C#, Java, HTML, XML, many more. FREE 30-Day Trial. www.slickedit.com/sourceforge _______________________________________________ [EMAIL PROTECTED] To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
