On Fri, Aug 05, 2022 at 02:38:13PM +0200, Bastien Nocera wrote: > On Thu, 2022-08-04 at 15:25 -0400, Alan Stern wrote: > > Have you considered what should happen if two processes share the > > same > > file descriptor (and hence the same usb_dev_state structure) and you > > want > > to revoke access for one of the processes but not the other? > > No, because this isn't something that happens in practice, as it's > simpler for each programme to open their own file descriptor and claim > the interfaces they need on their own. But it is possible for a program to open a USB device and then fork several children. The children would all share the same file descriptor. I have no idea how often this happens in practice. But kernel design is supposed to be based on correctness, not on handling only things that crop up "in practice". > > I have the feeling that this part of the function (matching the > > busnum > > and devnum values) doesn't belong here but rather with the iteration > > routines in your 2/2 patch. Filtering of devices generally is done > > as > > part of the iteration. As an added bonus, doing it that way means > > you > > don't need to pass around pointers to usb_revoke_match structures. > > I felt it better to have the filtering done in one place, to avoid > passing just a uid to check to that function. There's nothing wrong with passing just a uid. Especially since the same device might be open multiple times, for varying uids. > Should I rename the function something like usb_revoke_for_uid() ? Up to you. Alan Stern
