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Anna-Maria Gleixner eb27926ba0 hrtimer: Make hrtimer_cpu_base.next_timer handling unconditional
hrtimer_cpu_base.next_timer stores the pointer to the next expiring timer
in a CPU base.

This pointer cannot be dereferenced and is solely used to check whether a
hrtimer which is removed is the hrtimer which is the first to expire in the
CPU base. If this is the case, then the timer hardware needs to be
reprogrammed to avoid an extra interrupt for nothing.

Again, this is conditional functionality, but there is no compelling reason
to make this conditional. As a preparation, hrtimer_cpu_base.next_timer
needs to be available unconditonally.

Aside of that the upcoming support for softirq based hrtimers requires access
to this pointer unconditionally as well, so our motivation is not entirely
simplicity based.

Make the update of hrtimer_cpu_base.next_timer unconditional and remove the
#ifdef cruft. The impact on CONFIG_HIGH_RES_TIMERS=n && CONFIG_NOHZ=n is
marginal as it's just a store on an already dirtied cacheline.

No functional change.

Signed-off-by: Anna-Maria Gleixner <anna-maria@linutronix.de>
Cc: Christoph Hellwig <hch@lst.de>
Cc: John Stultz <john.stultz@linaro.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: keescook@chromium.org
Link: http://lkml.kernel.org/r/20171221104205.7269-17-anna-maria@linutronix.de
Signed-off-by: Ingo Molnar <mingo@kernel.org>
2018-01-16 02:35:47 +01:00
arch Merge branch 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-01-05 12:23:57 -08:00
block block-throttle: avoid double charge 2017-12-20 11:10:17 -07:00
certs License cleanup: add SPDX GPL-2.0 license identifier to files with no license 2017-11-02 11:10:55 +01:00
crypto Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2018-01-05 12:10:06 -08:00
Documentation Merge branch 'timers/urgent' into timers/core, to pick up dependent fix 2018-01-16 02:33:42 +01:00
drivers Merge branch 'timers/urgent' into timers/core, to pick up dependent fix 2018-01-16 02:33:42 +01:00
firmware kbuild: remove all dummy assignments to obj- 2017-11-18 11:46:06 +09:00
fs for-4.15-rc7-tag 2018-01-05 13:02:46 -08:00
include hrtimer: Make hrtimer_cpu_base.next_timer handling unconditional 2018-01-16 02:35:47 +01:00
init Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-12-31 12:27:19 -08:00
ipc Rename superblock flags (MS_xyz -> SB_xyz) 2017-11-27 13:05:09 -08:00
kernel hrtimer: Make hrtimer_cpu_base.next_timer handling unconditional 2018-01-16 02:35:47 +01:00
lib Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6 2018-01-05 12:10:06 -08:00
mm mm/sparse.c: wrong allocation for mem_section 2018-01-04 16:45:09 -08:00
net strparser: Call sock_owned_by_user_nocheck 2017-12-28 14:28:22 -05:00
samples Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf 2017-12-03 13:08:30 -05:00
scripts Merge branch 'locking-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-12-15 11:44:59 -08:00
security Merge branch 'x86-pti-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2018-01-03 16:41:07 -08:00
sound ALSA: hda - Fix missing COEF init for ALC225/295/299 2017-12-27 08:53:59 +01:00
tools posix-timers: Prevent UB from shifting negative signed value 2018-01-04 14:57:10 +01:00
usr initramfs: fix initramfs rebuilds w/ compression after disabling 2017-11-03 07:39:19 -07:00
virt KVM/ARM Fixes for v4.15, Round 2 2017-12-18 12:57:43 +01:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore
.gitattributes .gitattributes: set git diff driver for C source code files 2016-10-07 18:46:30 -07:00
.gitignore Kbuild misc updates for v4.15 2017-11-17 17:51:33 -08:00
.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: Remove Matt Fleming as EFI co-maintainer 2018-01-03 14:03:18 +01:00
Makefile Linux 4.15-rc6 2017-12-31 14:47:43 -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.