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Filename Latest commit message Latest commit date
John Stultz 0bcdc0987c time: Fix ktime_get_raw() incorrect base accumulation
In comqit fc6eead7c1 ("time: Clean up CLOCK_MONOTONIC_RAW time
handling"), the following code got mistakenly added to the update of the
raw timekeeper:

 /* Update the monotonic raw base */
 seconds = tk->raw_sec;
 nsec = (u32)(tk->tkr_raw.xtime_nsec >> tk->tkr_raw.shift);
 tk->tkr_raw.base = ns_to_ktime(seconds * NSEC_PER_SEC + nsec);

Which adds the raw_sec value and the shifted down raw xtime_nsec to the
base value.

But the read function adds the shifted down tk->tkr_raw.xtime_nsec value
another time, The result of this is that ktime_get_raw() users (which are
all internal users) see the raw time move faster then it should (the rate
at which can vary with the current size of tkr_raw.xtime_nsec), which has
resulted in at least problems with graphics rendering performance.

The change tried to match the monotonic base update logic:

 seconds = (u64)(tk->xtime_sec + tk->wall_to_monotonic.tv_sec);
 nsec = (u32) tk->wall_to_monotonic.tv_nsec;
 tk->tkr_mono.base = ns_to_ktime(seconds * NSEC_PER_SEC + nsec);

Which adds the wall_to_monotonic.tv_nsec value, but not the
tk->tkr_mono.xtime_nsec value to the base.

To fix this, simplify the tkr_raw.base accumulation to only accumulate the
raw_sec portion, and do not include the tkr_raw.xtime_nsec portion, which
will be added at read time.

Fixes: fc6eead7c1 ("time: Clean up CLOCK_MONOTONIC_RAW time handling")
Reported-and-tested-by: Chris Wilson <chris@chris-wilson.co.uk>
Signed-off-by: John Stultz <john.stultz@linaro.org>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Stephen Boyd <stephen.boyd@linaro.org>
Cc: Will Deacon <will.deacon@arm.com>
Cc: Miroslav Lichvar <mlichvar@redhat.com>
Cc: Daniel Mentz <danielmentz@google.com>
Link: http://lkml.kernel.org/r/1503701824-1645-1-git-send-email-john.stultz@linaro.org
2017-08-26 16:06:12 +02:00
arch Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-08-20 09:36:52 -07:00
block blk-mq-pci: add a fallback when pci_irq_get_affinity returns NULL 2017-08-18 08:08:14 -06:00
certs modsign: add markers to endif-statements in certs/Makefile 2017-07-14 11:01:37 +10:00
crypto crypto: authencesn - Fix digest_null crash 2017-07-18 17:01:11 +08:00
Documentation printk-formats.txt: Better describe the difference between %pS and %pF 2017-08-16 21:09:45 +02:00
drivers Merge branch 'timers-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-08-20 09:34:24 -07:00
firmware
fs Merge branch 'x86-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-08-20 09:36:52 -07:00
include Merge branch 'perf-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-08-20 09:20:57 -07:00
init random: do not ignore early device randomness 2017-07-12 16:26:00 -07:00
ipc ipc: add missing container_of()s for randstruct 2017-08-02 17:16:12 -07:00
kernel time: Fix ktime_get_raw() incorrect base accumulation 2017-08-26 16:06:12 +02:00
lib kernel/watchdog: Prevent false positives with turbo modes 2017-08-18 12:35:02 +02:00
mm Sanitize 'move_pages()' permission checks 2017-08-20 13:26:27 -07:00
net net_sched: remove warning from qdisc_hash_add 2017-08-15 17:16:39 -07:00
samples samples/bpf: fix bpf tunnel cleanup 2017-07-31 22:02:47 -07:00
scripts parse-maintainers: Move matching sections from MAINTAINERS 2017-08-08 11:16:14 -07:00
security Now that IPC and other changes have landed, enable manual markings for 2017-07-19 08:55:18 -07:00
sound ALSA: emu10k1: Fix forgotten user-copy conversion in init code 2017-08-18 10:59:02 +02:00
tools test_kmod: fix description for -s -and -c parameters 2017-08-18 15:32:01 -07:00
usr ramfs: clarify help text that compression applies to ramfs as well as legacy ramdisk. 2017-07-06 16:24:30 -07:00
virt KVM/ARM Fixes for v4.13-rc4 2017-08-03 17:59:58 +02:00
.cocciconfig
.get_maintainer.ignore
.gitattributes
.gitignore
.mailmap power supply and reset changes for the v4.12 series (part 2) 2017-05-12 12:02:21 -07:00
COPYING
CREDITS
Kbuild
Kconfig
MAINTAINERS Merge branch 'irq-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-08-20 09:07:56 -07:00
Makefile Linux 4.13-rc6 2017-08-20 14:13:52 -07:00
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.