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Linux kernel for uConsole
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John Keeping 2d078c2d04 drm/rockchip: fix VOP vblank race 
We have seen a case of a bad reference count for vblanks with the
Rockchip VOP:

	------------[ cut here ]------------
	WARNING: CPU: 1 PID: 383 at drivers/gpu/drm/drm_irq.c:1198 drm_vblank_put+0x40/0xcc
	Modules linked in: brcmfmac brcmutil
	CPU: 1 PID: 383 Comm: kworker/u8:2 Not tainted 4.9.75-rt60 #1
	Hardware name: Rockchip (Device Tree)
	Workqueue: events_unbound flip_worker
	Backtrace:
	[<c010b7b0>] (dump_backtrace) from [<c010ba4c>] (show_stack+0x18/0x1c)
	 r7:c0b1b13c r6:600b0013 r5:00000000 r4:c0b1b13c
	[<c010ba34>] (show_stack) from [<c032d248>] (dump_stack+0x78/0x94)
	[<c032d1d0>] (dump_stack) from [<c011e6e8>] (__warn+0xe4/0x104)
	 r7:00000009 r6:c03cf26c r5:00000000 r4:00000000
	[<c011e604>] (__warn) from [<c011e7c0>] (warn_slowpath_null+0x28/0x30)
	 r9:eeb443a0 r8:eeb443c8 r7:ee8a5ec0 r6:ee8a5ec0 r5:edb47f00 r4:ee096200
	[<c011e798>] (warn_slowpath_null) from [<c03cf26c>] (drm_vblank_put+0x40/0xcc)
	[<c03cf22c>] (drm_vblank_put) from [<c03cf310>] (drm_crtc_vblank_put+0x18/0x1c)
	 r5:edb47f00 r4:ee3c8a80
	[<c03cf2f8>] (drm_crtc_vblank_put) from [<c03ef9b4>] (vop_fb_unref_worker+0x18/0x24)
	[<c03ef99c>] (vop_fb_unref_worker) from [<c03df194>] (flip_worker+0x98/0xb4)
	 r5:edb47f00 r4:eeb443a8
	[<c03df0fc>] (flip_worker) from [<c0134808>] (process_one_work+0x1a8/0x2fc)
	 r9:00000000 r8:ee807d00 r7:00000000 r6:ee809c00 r5:eeb443a8 r4:edfe5f80
	[<c0134660>] (process_one_work) from [<c01358ec>] (worker_thread+0x2ac/0x458)
	 r10:00000088 r9:edfe5f98 r8:ee809c2c r7:c0b04100 r6:ee809c00 r5:ee809c00
	 r4:edfe5f80
	[<c0135640>] (worker_thread) from [<c013a0bc>] (kthread+0xfc/0x10c)
	 r10:00000000 r9:00000000 r8:c0135640 r7:edfe5f80 r6:00000000 r5:edf0e240
	 r4:ee8a4000 r3:ed194e00
	[<c0139fc0>] (kthread) from [<c0107cb8>] (ret_from_fork+0x14/0x3c)
	 r8:00000000 r7:00000000 r6:00000000 r5:c0139fc0 r4:edf0e240
	---[ end trace 0000000000000002 ]---

It seems that this is caused by unfortunate timing between
vop_crtc_atomic_flush() and vop_handle_vblank() given the following
ordering:

	atomic_flush		handle_vblank
	------------		-------------

	drm_flip_work_queue
	set_bit
	     			if (test_and_clear_bit(...))
	     				drm_flip_work_commit
	drm_vblank_get

This results in vop_fb_unref_worker (called as flip work) decrementing
the vblank refcount before it has been incremented.

Signed-off-by: John Keeping <john@metanate.com>
Reviewed-by: Sandy huang <hjc@rock-chips.com>
Signed-off-by: Sandy Huang <hjc@rock-chips.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20180328160351.23763-1-john@metanate.com
2018-04-17 09:18:16 +08:00
arch Linux 4.16-rc7 2018-03-28 14:30:41 +10:00
block for-linus-20180302 2018-03-02 09:35:36 -08:00
certs certs/blacklist_nohashes.c: fix const confusion in certs blacklist 2018-02-21 15:35:43 -08:00
crypto X.509: fix NULL dereference when restricting key with unsupported_sig 2018-02-22 14:38:34 +00:00
Documentation drm/docs: Remove the rcar alpha from the csv file 2018-04-16 21:21:48 +02:00
drivers drm/rockchip: fix VOP vblank race 2018-04-17 09:18:16 +08:00
firmware kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
fs Merge branch 'akpm' (patches from Andrew) 2018-03-22 18:48:43 -07:00
include drm/blend: Add a generic alpha property 2018-04-16 21:17:29 +02:00
init jump_label: Disable jump labels in __exit code 2018-03-20 08:57:17 +01:00
ipc Revert "mqueue: switch to on-demand creation of internal mount" 2018-03-24 19:34:23 -05:00
kernel Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-03-25 07:34:50 -10:00
lib Merge branch 'akpm' (patches from Andrew) 2018-03-22 18:48:43 -07:00
LICENSES LICENSES: Add MPL-1.1 license 2018-01-06 10:59:44 -07:00
mm mm, thp: do not cause memcg oom for thp 2018-03-22 17:07:02 -07:00
net Two more fixes (in three patches): 2018-03-22 13:19:10 -04:00
samples - do not build samples when cross compiling (Michal Hocko) 2018-02-27 10:39:29 -08:00
scripts Merge airlied/drm-next into drm-misc-next 2018-03-30 12:35:45 -04:00
security integrity/security: fix digsig.c build error with header file 2018-02-22 20:09:08 -08:00
sound Linux 4.16-rc7 2018-03-28 14:30:41 +10:00
tools Merge branch 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-03-25 07:36:02 -10:00
usr initramfs: fix initramfs rebuilds w/ compression after disabling 2017-11-03 07:39:19 -07:00
virt kvm/arm fixes for 4.16, take 2 2018-03-15 21:45:37 +01:00
.cocciconfig
.get_maintainer.ignore
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore .gitignore: ignore ASN.1 auto generated files 2018-02-14 21:05:38 +01:00
.mailmap mailmap: update Mark Yao's email address 2018-01-04 16:45:09 -08:00
COPYING
CREDITS MAINTAINERS: update TPM driver infrastructure changes 2017-11-09 17:58:40 -08:00
Kbuild Kbuild updates for v4.15 2017-11-17 17:45:29 -08:00
Kconfig License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
MAINTAINERS MAINTAINERS: Add drm/xen-front maintainer entry 2018-04-03 16:12:47 +03:00
Makefile Linux 4.16-rc7 2018-03-25 12:44:30 -10:00
README README: add a new README file, pointing to the Documentation/ 2016-10-24 08:12:35 -02:00

README 

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

This file was moved to Documentation/admin-guide/README.rst

Please notice that there are several guides for kernel developers and users.
These guides can be rendered in a number of formats, like HTML and PDF.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.

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.