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621bd0f698
linux/drivers/gpu/drm
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Daniel Vetter 621bd0f698 drm: Fix locking for sysfs dpms file 
With atomic drivers we need to make sure that (at least in general)
property reads hold the right locks. But the legacy dpms property is
special and can be read locklessly. Since userspace loves to just
randomly look at that all the time (like with "status") do that.

To make it clear that we play tricks use the READ_ONCE compiler
barrier (and also for paranoia).

Note that there's not really anything bad going on since even with the
new atomic paths we eventually end up not chasing any pointers (and
hence possibly freed memory and other fun stuff). The locking WARNING
has been added in

commit 88a48e297b
Author: Rob Clark <robdclark@gmail.com>
Date:   Thu Dec 18 16:01:50 2014 -0500

    drm: add atomic properties

but since drivers are converting not everyone will have seen this from
the start.

Jens reported this and submitted a patch to just grab the
mode_config.connection_mutex, but we can do a bit better.

v2: Remove unused variables I failed to git add for real.

Reference: http://mid.gmane.org/20150928194822.GA3930@kernel.dk
Reported-by: Jens Axboe <axboe@fb.com>
Tested-by: Jens Axboe <axboe@fb.com>
Cc: Rob Clark <robdclark@gmail.com>
Cc: stable@vger.kernel.org
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>
2015-10-09 10:19:14 +10:00
..
amd drm/amdgpu: fix memory leak in amdgpu_vm_update_page_directory 2015-10-08 12:18:23 -04:00
armada drm/armada: Use new drm_fb_helper functions 2015-08-06 14:12:56 +02:00
ast drm/ast: Don't grab dev->struct_mutex for in mmap offset ioctl 2015-08-10 13:36:55 +02:00
atmel-hlcdc Linux 4.2-rc8 2015-08-24 16:36:42 +10:00
bochs drm/bochs: Don't grab dev->struct_mutex for in mmap offset ioctl 2015-08-10 13:37:04 +02:00
bridge Merge branch 'drm-dwhdmi-devel' of git://ftp.arm.linux.org.uk/~rmk/linux-arm into drm-next 2015-08-27 13:01:57 +10:00
cirrus drm/cirrus: Don't grab dev->struct_mutex for in mmap offset ioctl 2015-08-10 13:37:27 +02:00
exynos drm/exynos: Staticize local function in exynos_drm_gem.c 2015-10-01 14:29:51 +09:00
fsl-dcu drm/layerscape: fix handling fsl_dcu_drm_plane_index result 2015-09-24 08:13:09 +10:00
gma500 drm/gma500: Use new drm_fb_helper functions 2015-08-06 14:12:59 +02:00
i2c Merge remote-tracking branches 'asoc/topic/rcar', 'asoc/topic/reg-default', 'asoc/topic/rl6231', 'asoc/topic/rockchip' and 'asoc/topic/rt286' into asoc-next 2015-08-30 15:55:54 +01:00
i810
i915 drm/dp/mst: split connector registration into two parts (v2) 2015-10-02 15:34:41 +10:00
imx Merge branch 'drm-dwhdmi-devel' of git://ftp.arm.linux.org.uk/~rmk/linux-arm into drm-next 2015-08-27 13:01:57 +10:00
mga
mgag200 drm/mgag200: Fix driver_load error handling 2015-09-24 08:10:44 +10:00
msm gpu/drm: Kill off set_irq_flags usage 2015-09-16 16:53:38 +02:00
nouveau Merge branch 'drm-fixes' of git://people.freedesktop.org/~airlied/linux 2015-09-11 09:35:56 -07:00
omapdrm drm/omap: Use new drm_fb_helper functions 2015-08-06 14:13:03 +02:00
panel drm/panel: Add support for LG LG4573 480x800 4.3" panel 2015-08-14 21:35:35 +02:00
qxl drm/qxl: avoid dependency lock 2015-10-07 15:33:45 +10:00
r128
radeon drm/radeon: restore the fbdev mode in lastclose 2015-10-05 09:44:18 -04:00
rcar-du drm/atomic: pass old crtc state to atomic_begin/flush. 2015-07-27 16:23:22 +02:00
rockchip drm/rockchip: vop: support plane scale 2015-08-26 14:16:26 +08:00
savage
shmobile drm: Simplify drm_for_each_legacy_plane arguments 2015-07-22 16:25:45 +02:00
sis
sti Merge branch 'drm-sti-next-atomic-2015-08-11' of http://git.linaro.org/people/benjamin.gaignard/kernel into drm-next 2015-08-14 10:14:23 +10:00
tdfx
tegra drm/tegra: Changes for v4.3-rc1 2015-08-17 15:52:39 +10:00
tilcdc drm/tilcdc: panel: make better use of gpiod API 2015-07-06 10:10:21 +02:00
ttm drm/ttm: Fix memory space allocation v2 2015-09-15 00:57:01 -07:00
udl drm/udl: Use new drm_fb_helper functions 2015-08-06 14:13:00 +02:00
vgem mm: mark most vm_operations_struct const 2015-09-10 13:29:01 -07:00
via treewide: fix typos in comment blocks 2015-08-07 14:46:24 +02:00
virtio drm/virtio: Use new drm_fb_helper functions 2015-08-06 14:13:07 +02:00
vmwgfx Merge tag 'vmwgfx-fixes-4.3-151001' of git://people.freedesktop.org/~thomash/linux into drm-fixes 2015-10-02 10:46:51 +10:00
ati_pcigart.c
drm_agpsupport.c
drm_atomic_helper.c Merge branch 'drm-next' of git://people.freedesktop.org/~airlied/linux 2015-09-04 15:49:32 -07:00
drm_atomic.c drm/atomic: Fix bookkeeping with TEST_ONLY, v3. 2015-09-01 11:57:06 +03:00
drm_auth.c
drm_bridge.c
drm_bufs.c
drm_cache.c drm: Avoid the double clflush on the last cache line in drm_clflush_virt_range() 2015-06-19 17:25:17 +02:00
drm_context.c drm: Convert drm_legacy_ctxbitmap_init to void return type 2015-07-02 17:00:48 +02:00
drm_crtc_helper.c drm: Make the connector dpms callback return a value, v2. 2015-07-27 16:23:28 +02:00
drm_crtc_internal.h
drm_crtc.c Linux 4.2-rc7 2015-08-17 14:13:53 +10:00
drm_debugfs.c
drm_dma.c
drm_dp_helper.c drm/dp: Add dp_aux_i2c_speed_khz module param to set the assume i2c bus speed 2015-09-02 16:13:43 +03:00
drm_dp_mst_topology.c drm/dp/mst: add some defines for logical/physical ports 2015-10-02 15:34:42 +10:00
drm_drv.c Merge tag 'topic/connector-locking-2015-07-23' of git://anongit.freedesktop.org/drm-intel into drm-next 2015-07-24 14:30:29 +10:00
drm_edid_load.c
drm_edid.c drm/edid: Use ARRAY_SIZE in drm_add_modes_noedid 2015-08-11 12:04:16 +02:00
drm_encoder_slave.c
drm_fb_cma_helper.c drm/fb_cma_helper: Use new drm_fb_helper functions 2015-08-06 14:13:00 +02:00
drm_fb_helper.c drm: handle cursor_set2 in restore_fbdev_mode 2015-10-02 15:30:41 +10:00
drm_flip_work.c
drm_fops.c
drm_gem_cma_helper.c drm/cma-helper: Don't grab dev->struct_mutex for in mmap offset ioctl 2015-08-10 13:37:36 +02:00
drm_gem.c drm/gem: Be more friendly with locking checks 2015-08-10 13:35:49 +02:00
drm_global.c
drm_hashtab.c
drm_info.c
drm_internal.h
drm_ioc32.c Merge tag 'topic/drm-misc-2015-07-23' of git://anongit.freedesktop.org/drm-intel into drm-next 2015-07-24 14:28:16 +10:00
drm_ioctl.c drm: Allow also control clients to check the drm version 2015-09-24 00:24:24 -07:00
drm_irq.c Linux 4.2-rc7 2015-08-17 14:13:53 +10:00
drm_legacy.h drm: Convert drm_legacy_ctxbitmap_init to void return type 2015-07-02 17:00:48 +02:00
drm_lock.c drm: Reject DRI1 hw lock ioctl functions for kms drivers 2015-07-02 17:00:48 +02:00
drm_memory.c
drm_mipi_dsi.c
drm_mm.c
drm_modes.c
drm_modeset_lock.c drm: Remove __drm_modeset_lock_all 2015-08-06 14:13:02 +02:00
drm_of.c drm: Add modeset object iterators 2015-07-22 16:25:45 +02:00
drm_panel.c
drm_pci.c
drm_plane_helper.c drm/atomic: pass old crtc state to atomic_begin/flush. 2015-07-27 16:23:22 +02:00
drm_platform.c
drm_prime.c drm: prime: Document gem_prime_mmap 2015-06-19 17:50:05 +02:00
drm_probe_helper.c drm: Add a non-locking version of drm_kms_helper_poll_enable(), v2 2015-09-30 16:04:08 +03:00
drm_rect.c
drm_scatter.c
drm_sysfs.c drm: Fix locking for sysfs dpms file 2015-10-09 10:19:14 +10:00
drm_trace_points.c
drm_trace.h
drm_vm.c
drm_vma_manager.c
Kconfig Merge branch 'drm-next-fsl-dcu' of https://github.com/Jianwei-Wang/linux-drm-fsl-dcu into drm-next 2015-08-20 14:11:17 +10:00
Makefile drm/layerscape: Add Freescale DCU DRM driver 2015-08-19 22:23:04 -04:00