Hi Tejun, On 5/9/07, Tejun Heo <[EMAIL PROTECTED]> wrote: > Chris Rankin wrote: > > --- Tejun Heo <[EMAIL PROTECTED]> wrote: > >> Okay, here's a half-assed fix. With this patch applied, if you try to > >> unload a module while you're opening it's dev attribute, kernel will > >> oops later when the file is accessed or closed later but it should fix > >> the bug winecfg triggers. I really dunno how to fix this the right way > >> in the stable kernel. Better ideas? Anyone? > > > > How about a WARN() and a small(?) memory leak? Better than an oops, surely? > > Device node creation/deletion can be quite often depending on > configuration, so I don't think we can afford memory leak here. It can > develop into a big problem for long running hosts. IMHO, just > introducing module unload/deletion race is much better. It's the lesser > evil, difficult to trigger and already broken in other places anyway. > > I think we need to hear what other people are thinking about it. Cc'ing > Maneesh, Dmitry and Cornelia. The whole thread can be read at... > > http://thread.gmane.org/gmane.linux.usb.devel/53559 > http://thread.gmane.org/gmane.linux.usb.devel/53846 > > The thread is rather long but just reading the message from the second > URL should be enough. The problem is that dev->devt_attr (class dev has > the same problem) is deallocated when the device is deleted. If the dev > sysfs attribute has users at that point, the dev sysfs node is left with > garbled struct attribute causing oops later. > > IMHO, the proper fix for this is immediate-disconnect which is no in -mm > as the problem is caused by expecting immediate-disconnect behavior when > it isn't implemented. > > As written above, I think it's better to risk module unload / sysfs race > than keeping the current sysfs deletion / open race. What do you guys > think? >
How about embedding struct attribute fro devt into struct [class_]device for now? It is not too big and device is still going to be pinned into memory while there are sysfs users... I don't like fattening of device structures but leaks and/or oopses are worse in my book. -- Dmitry ------------------------------------------------------------------------- This SF.net email is sponsored by DB2 Express Download DB2 Express C - the FREE version of DB2 express and take control of your XML. No limits. Just data. Click to get it now. http://sourceforge.net/powerbar/db2/ _______________________________________________ linux-usb-devel@lists.sourceforge.net To unsubscribe, use the last form field at: https://lists.sourceforge.net/lists/listinfo/linux-usb-devel
