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Nicolai Hähnle 6baa5c60a9 locking/ww_mutex: Add waiters in stamp order
Add regular waiters in stamp order. Keep adding waiters that have no
context in FIFO order and take care not to starve them.

While adding our task as a waiter, back off if we detect that there is
a waiter with a lower stamp in front of us.

Make sure to call lock_contended even when we back off early.

For w/w mutexes, being first in the wait list is only stable when
taking the lock without a context. Therefore, the purpose of the first
flag is split into two: 'first' remains to indicate whether we want to
spin optimistically, while 'handoff' indicates that we should be
prepared to accept a handoff.

For w/w locking with a context, we always accept handoffs after the
first schedule(), to handle the following sequence of events:

 1. Task #0 unlocks and hands off to Task #2 which is first in line

 2. Task #1 adds itself in front of Task #2

 3. Task #2 wakes up and must accept the handoff even though it is no
    longer first in line

Signed-off-by: Nicolai Hähnle <nicolai.haehnle@amd.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: =?UTF-8?q?Nicolai=20H=C3=A4hnle?= <Nicolai.Haehnle@amd.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Maarten Lankhorst <dev@mblankhorst.nl>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: dri-devel@lists.freedesktop.org
Link: http://lkml.kernel.org/r/1482346000-9927-7-git-send-email-nhaehnle@gmail.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
History 2017-01-14 11:14:42 +01:00
arch sched/core: Remove set_task_state() 2017-01-14 11:14:16 +01:00
block Merge branch 'for-linus' of git://git.kernel.dk/linux-block 2017-01-04 09:03:37 -08:00
certs certs: Add a secondary system keyring that can be added to dynamically 2016-04-11 22:48:09 +01:00
crypto crypto: testmgr - Use heap buffer for acomp test input 2016-12-27 17:32:11 +08:00
Documentation mm: add documentation for page fragment APIs 2017-01-10 18:31:55 -08:00
drivers sched/core: Remove set_task_state() 2017-01-14 11:14:16 +01:00
firmware WHENCE: use https://linuxtv.org for LinuxTV URLs 2015-12-04 10:35:11 -02:00
fs ocfs2: fix crash caused by stale lvb with fsdlm plugin 2017-01-10 18:31:54 -08:00
include locking/ww_mutex: Add waiters in stamp order 2017-01-14 11:14:42 +01:00
init cgroup: move CONFIG_SOCK_CGROUP_DATA to init/Kconfig 2017-01-11 09:47:10 -05:00
ipc ipc/sem.c: fix incorrect sem_lock pairing 2017-01-10 18:31:55 -08:00
kernel locking/ww_mutex: Add waiters in stamp order 2017-01-14 11:14:42 +01:00
lib lib/Kconfig.debug: fix frv build failure 2017-01-10 18:31:55 -08:00
mm mm/hugetlb.c: fix reservation race when freeing surplus pages 2017-01-10 18:31:55 -08:00
net Merge branch 'akpm' (patches from Andrew) 2017-01-11 11:15:15 -08:00
samples vfio-mdev: fix some error codes in the sample code 2017-01-04 08:32:23 -07:00
scripts gcc-plugins: update gcc-common.h for gcc-7 2017-01-03 12:08:59 -08:00
security Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
sound Revert "ALSA: firewire-lib: change structure member with proper type" 2017-01-05 08:39:47 +01:00
tools Merge branch 'akpm' (patches from Andrew) 2017-01-11 11:15:15 -08:00
usr kbuild: initramfs cleanup, set target from Kconfig 2017-01-05 09:40:16 -08:00
virt Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-12-25 14:30:04 -08:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore Add hch to .get_maintainer.ignore 2015-08-21 14:30:10 -07:00
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore Merge branch 'misc' of git://git.kernel.org/pub/scm/linux/kernel/git/mmarek/kbuild 2016-08-02 16:48:52 -04:00
.mailmap mailmap: add codeaurora.org names for nameless email commits 2017-01-10 18:31:55 -08:00
COPYING [PATCH] update FSF address in COPYING 2005-09-10 10:06:29 -07:00
CREDITS CREDITS: Remove outdated address information 2016-12-21 15:21:29 -08:00
Kbuild scripts/gdb: provide linux constants 2016-05-23 17:04:14 -07:00
Kconfig kbuild: migrate all arch to the kconfig mainmenu upgrade 2010-09-19 22:54:11 -04:00
MAINTAINERS MAINTAINERS: remove duplicate bug filling description 2017-01-10 18:31:54 -08:00
Makefile Linux 4.10-rc3 2017-01-08 14:18:17 -08:00
README README: add a new README file, pointing to the Documentation/ 2016-10-24 08:12:35 -02:00

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.