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Linux kernel for uConsole
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Rodrigo Siqueira 5d60d39814 drm/drm_vblank: Change EINVAL by the correct errno 
[ Upstream commit aed6105b28 ]

For historical reasons, the function drm_wait_vblank_ioctl always return
-EINVAL if something gets wrong. This scenario limits the flexibility
for the userspace to make detailed verification of any problem and take
some action. In particular, the validation of “if (!dev->irq_enabled)”
in the drm_wait_vblank_ioctl is responsible for checking if the driver
support vblank or not. If the driver does not support VBlank, the
function drm_wait_vblank_ioctl returns EINVAL, which does not represent
the real issue; this patch changes this behavior by return EOPNOTSUPP.
Additionally, drm_crtc_get_sequence_ioctl and
drm_crtc_queue_sequence_ioctl, also returns EINVAL if vblank is not
supported; this patch also changes the return value to EOPNOTSUPP in
these functions. Lastly, these functions are invoked by libdrm, which is
used by many compositors; because of this, it is important to check if
this change breaks any compositor. In this sense, the following projects
were examined:

* Drm-hwcomposer
* Kwin
* Sway
* Wlroots
* Wayland
* Weston
* Mutter
* Xorg (67 different drivers)

For each repository the verification happened in three steps:

* Update the main branch
* Look for any occurrence of "drmCrtcQueueSequence",
  "drmCrtcGetSequence", and "drmWaitVBlank" with the command git grep -n
  "STRING".
* Look in the git history of the project with the command
git log -S<STRING>

None of the above projects validate the use of EINVAL when using
drmWaitVBlank(), which make safe, at least for these projects, to change
the return values. On the other hand, mesa and xserver project uses
drmCrtcQueueSequence() and drmCrtcGetSequence(); this change is harmless
for both projects.

Change since V5 (Pekka Paalanen):
 - Check if the change also affects Mutter

Change since V4 (Daniel):
 - Also return EOPNOTSUPP in drm_crtc_[get|queue]_sequence_ioctl

Change since V3:
 - Return EINVAL for _DRM_VBLANK_SIGNAL (Daniel)

Change since V2:
 Daniel Vetter and Chris Wilson
 - Replace ENOTTY by EOPNOTSUPP
 - Return EINVAL if the parameters are wrong

Cc: Keith Packard <keithp@keithp.com>
Cc: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Ville Syrjälä <ville.syrjala@linux.intel.com>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Pekka Paalanen <pekka.paalanen@collabora.com>
Signed-off-by: Rodrigo Siqueira <rodrigosiqueiramelo@gmail.com>
Reviewed-by: Daniel Vetter <daniel@ffwll.ch>
Acked-by: Pekka Paalanen <pekka.paalanen@collabora.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191002140516.adeyj3htylimmlmg@smtp.gmail.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
2019-12-31 16:35:01 +01:00
arch ARM: tegra: Fix FLOW_CTLR_HALT register clobbering by tegra_resume() 2019-12-21 10:57:36 +01:00
block blk-mq: make sure that line break can be printed 2019-12-17 20:35:48 +01:00
certs export.h: remove VMLINUX_SYMBOL() and VMLINUX_SYMBOL_STR() 2018-08-22 23:21:44 +09:00
crypto crypto: user - fix memory leak in crypto_report 2019-12-13 08:52:48 +01:00
Documentation mm, thp, proc: report THP eligibility for each vma 2019-12-17 20:35:45 +01:00
drivers drm/drm_vblank: Change EINVAL by the correct errno 2019-12-31 16:35:01 +01:00
firmware kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
fs Btrfs: fix removal logic of the tree mod log that leads to use-after-free issues 2019-12-31 16:34:44 +01:00
include block: Fix writeback throttling W=1 compiler warnings 2019-12-31 16:34:59 +01:00
init fork: fix some -Wmissing-prototypes warnings 2019-12-05 09:21:04 +01:00
ipc ipc/mqueue.c: only perform resource calculation if user valid 2019-08-06 19:06:52 +02:00
kernel kernel/module.c: wakeup processes in module_wq on module unload 2019-12-17 20:35:57 +01:00
lib idr: Fix idr_get_next_ul race with idr_remove 2019-12-17 20:36:02 +01:00
LICENSES LICENSES: Remove CC-BY-SA-4.0 license text 2018-10-18 11:28:50 +02:00
mm mm, thp, proc: report THP eligibility for each vma 2019-12-17 20:35:45 +01:00
net sctp: fully initialize v4 addr in some functions 2019-12-31 16:34:40 +01:00
samples samples: pktgen: fix proc_cmd command result check logic 2019-12-31 16:34:59 +01:00
scripts modpost: skip ELF local symbols during section mismatch check 2019-12-13 08:52:20 +01:00
security apparmor: delete the dentry in aafs_remove() to avoid a leak 2019-12-05 09:21:19 +01:00
sound ALSA: hda/ca0132 - Fix work handling in delayed HP detection 2019-12-31 16:34:47 +01:00
tools selftests/bpf: Correct path to include msg + path 2019-12-31 16:34:53 +01:00
usr kbuild: clean compressed initramfs image 2019-10-07 18:57:16 +02:00
virt KVM: arm/arm64: vgic: Don't rely on the wrong pending table 2019-12-13 08:52:45 +01:00
.clang-format clang-format: Set IndentWrappedFunctionNames false 2018-08-01 18:38:51 +02:00
.cocciconfig
.get_maintainer.ignore
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore Kbuild updates for v4.17 (2nd) 2018-04-15 17:21:30 -07:00
.mailmap libnvdimm-for-4.19_misc 2018-08-25 18:13:10 -07:00
COPYING COPYING: use the new text with points to the license files 2018-03-23 12:41:45 -06:00
CREDITS 9p: remove Ron Minnich from MAINTAINERS 2018-08-17 16:20:26 -07:00
Kbuild Kbuild updates for v4.15 2017-11-17 17:45:29 -08:00
Kconfig kconfig: move the "Executable file formats" menu to fs/Kconfig.binfmt 2018-08-02 08:06:55 +09:00
MAINTAINERS USB: rio500: Remove Rio 500 kernel driver 2019-10-17 13:44:47 -07:00
Makefile Linux 4.19.91 2019-12-21 10:57:45 +01:00
README Docs: Added a pointer to the formatted docs to README 2018-03-21 09:02:53 -06:00

README 

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.
See Documentation/00-INDEX for a list of what is contained in each file.

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.