drm: Return -ENOTTY for non-drm ioctls
Return -ENOTTY from drm_ioctl() when userspace passes in a cmd number
which doesn't relate to the drm subsystem.
Glibc uses the TCGETS ioctl to implement isatty(), and without this
change isatty() returns it incorrectly returns true for drm devices.
To test run this command:
$ if [ -t 0 ]; then echo is a tty; fi < /dev/dri/card0
which shows "is a tty" without this patch.
This may also modify memory which the userspace application is not
expecting.
Signed-off-by: Charles Baylis <cb-kernel@fishzet.co.uk>
Cc: stable@vger.kernel.org
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/YPG3IBlzaMhfPqCr@stando.fishzet.co.uk
This completes Emil's series of removing DRM_UNLOCKED from modern
drivers. It's entirely cargo-culted since we ignore it on
non-DRIVER_LEGACY drivers since:
commit ea487835e8
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date: Mon Sep 28 21:42:40 2015 +0200
drm: Enforce unlocked ioctl operation for kms driver ioctls
Now justifying why we can do this for legacy drives too (and hence
close the source of all the bogus copypasting) is a bit more involved.
DRM_UNLOCKED was introduced in:
commit ed8b670409
Author: Arnd Bergmann <arnd@arndb.de>
Date: Wed Dec 16 22:17:09 2009 +0000
drm: convert drm_ioctl to unlocked_ioctl
As a immediate hack to keep i810 happy, which would have deadlocked
without this trickery. The old BKL is automatically dropped in
schedule(), and hence the i810 vs. mmap_sem deadlock didn't actually
cause a real deadlock. But with a mutex it would. The solution was to
annotate these as DRM_UNLOCKED and mark i810 unsafe on SMP machines.
This conversion caused a regression, because unlike the BKL a mutex
isn't dropped over schedule (that thing again), which caused a vblank
wait in one thread to block the entire desktop and all its apps. Back
then we did vblank scheduling by blocking in the client, awesome isn't
it. This was fixed quickly in (ok not so quickly, took 2 years):
commit 8f4ff2b06a
Author: Ilija Hadzic <ihadzic@research.bell-labs.com>
Date: Mon Oct 31 17:46:18 2011 -0400
drm: do not sleep on vblank while holding a mutex
All the other DRM_UNLOCKED annotations for all the core ioctls was
work to reach finer-grained locking for modern drivers. This took
years, and culminated in:
commit fdd5b877e9
Author: Daniel Vetter <daniel.vetter@ffwll.ch>
Date: Sat Dec 10 22:52:54 2016 +0100
drm: Enforce BKL-less ioctls for modern drivers
DRM_UNLOCKED was never required by any legacy drivers, except for the
vblank_wait IOCTL. Therefore we will not regress these old drivers by
going back to where we've been in 2011. For all modern drivers nothing
will change.
To make this perfectly clear, also add a comment to DRM_UNLOCKED.
v2: Don't forget about drm_ioc32.c (Michel).
Cc: Michel Dänzer <michel@daenzer.net>
Cc: Emil Velikov <emil.l.velikov@gmail.com>
Acked-by: Emil Velikov <emil.velikov@collabora.com>
Acked-by: Michel Dänzer <michel@daenzer.net>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190605120835.2798-1-daniel.vetter@ffwll.ch
With the ioctl and driver prep done, we can remove everything else.
Reviewed-by: Sean Paul <seanpaul@chromium.org>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Cc: Gustavo Padovan <gustavo@padovan.org>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Sean Paul <seanpaul@chromium.org>
Cc: David Airlie <airlied@linux.ie>
Link: https://patchwork.freedesktop.org/patch/msgid/20180420065159.4531-4-daniel.vetter@ffwll.ch
Also unify/merge with the existing stuff.
I was a bit torn where to put this, but in the end I decided to put
all the ioctl/sysfs/debugfs stuff into drm-uapi.rst. That means we
have a bit a split with the other uapi related stuff used internally,
like drm_file.[hc], but I think overall this makes more sense.
If it's too confusing we can always add more cross-links to make it
more discoverable. But the auto-sprinkling of links kernel-doc already
does seems sufficient.
Also for prettier docs and more cross-links, switch the internal
defines over to an enum, as usual.
v2: Update kerneldoc fro drm_compat_ioctl too (caught by 0day), plus a
bit more drive-by polish.
v3: Fix typo, spotted by xerpi on irc (Sergi).
v4: Add missing space in comment (Neil).
Cc: Sergi Granell <xerpi.g.12@gmail.com>
Reviewed-by: Neil Armstrong <narmstrong@baylibre.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Link: http://patchwork.freedesktop.org/patch/msgid/20170404095304.17599-4-daniel.vetter@ffwll.ch
To match the drm_ioctl.c we already have.
v2: Remove spurious space (Ville).
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Reviewed-by: Ville Syrjälä <ville.syrjala@linux.intel.com>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Charles Baylis
Daniel Vetter
Al Viro