On Wed, Jan 26, 2011 at 07:20:07AM +1000, Linus Torvalds wrote: > On Wed, Jan 26, 2011 at 7:01 AM, Dmitry Torokhov > <dmitry.torokhov@xxxxxxxxx> wrote: > > > > BTW, another issue is that evdev's ioctl returns -EINVAL for unknown > > ioctls so applications would have hard time figuring out whether error > > returned because of kernel being too old or because they are trying to > > retrieve/establish invalid mapping if they had to go only by the error > > code. > > So that's just another evdev interface bug. Huh? I do not have lot of options here as far as error codes go. Invalid request, invalid data in request - all goes to EINVAL. > > > As far as I can see EINVAL is a proper error for unknown ioctls: > > > > [dtor@hammer work]$ man 2 ioctl | grep EINVAL > > EINVAL Request or argp is not valid. > > Yeah, there's some confusion there. > > The "unknown ioctl" error code is (for traditional reasons) ENOTTY, > but yes, the EINVAL thing admittedly has a lot of legacy use too. > > Inside the kernel, the preferred way to say "I don't recognize that > ioctl number" is actually ENOIOCTLCMD. That's exactly so that various > nested ioctl handlers can then tell the difference between "I didn't > recognize that ioctl" and "I understand what you asked me to do, but > your arguments were crap". > > vfs_ioctl() will then turn ENOIOCTLCMD to EINVAL to return to user space. OK, so I can change evdev to employ ENOIOCTLCMD where needed, bit that will not change older kernels where such distinction is needed (as never kernels do support newer ioctl). And even if I could go back it would not help since userspace still sees EINVAL only. -- Dmitry -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
