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Daniel Vetter 75426367cd drm/ioctl: Ditch DRM_UNLOCKED except for the legacy vblank ioctl
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
2019-06-21 19:13:10 +02:00
arch Merge branch 'topic/remove-fbcon-notifiers' into drm-misc-next 2019-06-19 12:33:05 +02:00
block blk-mq: remove WARN_ON(!q->elevator) from blk_mq_sched_free_requests 2019-06-13 03:05:58 -06:00
certs treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 36 2019-05-24 17:27:11 +02:00
crypto SPDX update for 5.2-rc4 2019-06-08 12:52:42 -07:00
Documentation drm/prime: Update docs 2019-06-21 11:48:09 +02:00
drivers drm/ioctl: Ditch DRM_UNLOCKED except for the legacy vblank ioctl 2019-06-21 19:13:10 +02:00
fs Fix rounding error in gfs2_iomap_page_prepare 2019-06-14 17:27:12 -10:00
include drm/ioctl: Ditch DRM_UNLOCKED except for the legacy vblank ioctl 2019-06-21 19:13:10 +02:00
init Char/Misc driver fixes for 5.2-rc4 2019-06-08 12:50:36 -07:00
ipc treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 441 2019-06-05 17:37:17 +02:00
kernel Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-06-16 07:22:56 -10:00
lib lib/genalloc: introduce chunk owners 2019-06-13 17:34:56 -10:00
LICENSES LICENSES: Rename other to deprecated 2019-05-03 06:34:32 -06:00
mm Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2019-06-16 07:28:14 -10:00
net SPDX update for 5.2-rc4 2019-06-08 12:52:42 -07:00
samples SPDX update for 5.2-rc4 2019-06-08 12:52:42 -07:00
scripts scripts/decode_stacktrace.sh: prefix addr2line with $CROSS_COMPILE 2019-06-13 17:34:56 -10:00
security Smack: Restore the smackfsdef mount option and add missing prefixes 2019-06-14 14:25:04 -10:00
sound sound fixes for 5.2-rc5 2019-06-14 05:37:06 -10:00
tools mm/devm_memremap_pages: fix final page put race 2019-06-13 17:34:56 -10:00
usr user/Makefile: Fix typo and capitalization in comment section 2018-12-11 00:18:03 +09:00
virt treewide: Replace GPLv2 boilerplate/reference with SPDX - rule 333 2019-06-05 17:37:06 +02:00
.clang-format Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2019-04-17 11:26:25 -07:00
.cocciconfig
.get_maintainer.ignore Opt out of scripts/get_maintainer.pl 2019-05-16 10:53:40 -07:00
.gitattributes
.gitignore .gitignore: exclude .get_maintainer.ignore and .gitattributes 2019-05-18 11:49:54 +09:00
.mailmap A reasonably busy cycle for docs, including: 2019-05-08 12:42:50 -07:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS MAINTAINERS: Farewell Martin Schwidefsky 2019-05-31 10:14:11 +02:00
Kbuild Kbuild updates for v5.1 2019-03-10 17:48:21 -07:00
Kconfig kconfig: move the "Executable file formats" menu to fs/Kconfig.binfmt 2018-08-02 08:06:55 +09:00
MAINTAINERS Linux 5.2-rc5 2019-06-19 12:07:29 +02:00
Makefile Linux 5.2-rc5 2019-06-16 08:49:45 -10:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.