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Thomas Gleixner f87cbcb345 timekeeping: Use READ/WRITE_ONCE() for tick_do_timer_cpu
tick_do_timer_cpu is used lockless to check which CPU needs to take care
of the per tick timekeeping duty. This is done to avoid a thundering
herd problem on jiffies_lock.

The read and writes are not annotated so KCSAN complains about data races:

  BUG: KCSAN: data-race in tick_nohz_idle_stop_tick / tick_nohz_next_event

  write to 0xffffffff8a2bda30 of 4 bytes by task 0 on cpu 26:
   tick_nohz_idle_stop_tick+0x3b1/0x4a0
   do_idle+0x1e3/0x250

  read to 0xffffffff8a2bda30 of 4 bytes by task 0 on cpu 16:
   tick_nohz_next_event+0xe7/0x1e0
   tick_nohz_get_sleep_length+0xa7/0xe0
   menu_select+0x82/0xb90
   cpuidle_select+0x44/0x60
   do_idle+0x1c2/0x250

  value changed: 0x0000001a -> 0xffffffff

Annotate them with READ/WRITE_ONCE() to document the intentional data race.

Reported-by: Mirsad Todorovac <mirsad.todorovac@alu.unizg.hr>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Tested-by: Sean Anderson <sean.anderson@seco.com>
Link: https://lore.kernel.org/r/87cyqy7rt3.ffs@tglx
2024-04-10 10:13:42 +02:00
arch Miscellaneous x86 fixes: 2024-04-07 09:33:21 -07:00
block block-6.9-20240405 2024-04-05 17:04:11 -07:00
certs This update includes the following changes: 2023-11-02 16:15:30 -10:00
crypto This push fixes a regression that broke iwd as well as a divide by 2024-03-25 10:48:23 -07:00
Documentation Devicetree fixes for v6.9, part 1: 2024-04-05 14:07:22 -07:00
drivers Miscellaneous x86 fixes: 2024-04-07 09:33:21 -07:00
fs nfsd-6.9 fixes: 2024-04-06 09:37:50 -07:00
include irqflags: Explicitly ignore lockdep_hrtimer_exit() argument 2024-04-08 16:34:18 +02:00
init init: open output files from cpio unpacking with O_LARGEFILE 2024-04-05 11:21:30 -07:00
io_uring io_uring/kbuf: hold io_buffer_list reference over mmap 2024-04-02 19:03:27 -06:00
ipc sysctl changes for v6.9-rc1 2024-03-18 14:59:13 -07:00
kernel timekeeping: Use READ/WRITE_ONCE() for tick_do_timer_cpu 2024-04-10 10:13:42 +02:00
lib stackdepot: rename pool_index to pool_index_plus_1 2024-04-05 11:21:31 -07:00
LICENSES LICENSES: Add the copyleft-next-0.3.1 license 2022-11-08 15:44:01 +01:00
mm x86/mm/pat: fix VM_PAT handling in COW mappings 2024-04-05 11:21:31 -07:00
net nfsd-6.9 fixes: 2024-04-06 09:37:50 -07:00
rust Kbuild updates for v6.9 2024-03-21 14:41:00 -07:00
samples Tracing updates for 6.9: 2024-03-18 15:11:44 -07:00
scripts Four small documentation fixes. 2024-04-02 12:44:09 -07:00
security security: Place security_path_post_mknod() where the original IMA call was 2024-04-03 10:21:32 -07:00
sound ASoC: Fixes for v6.9 2024-04-05 08:48:12 +02:00
tools selftests/timers/posix_timers: Reimplement check_timer_distribution() 2024-04-09 17:48:19 +02:00
usr Kbuild updates for v6.8 2024-01-18 17:57:07 -08:00
virt KVM Xen and pfncache changes for 6.9: 2024-03-11 10:42:55 -04:00
.clang-format clang-format: Update with v6.7-rc4's for_each macro list 2023-12-08 23:54:38 +01:00
.cocciconfig
.editorconfig Add .editorconfig file for basic formatting 2023-12-28 16:22:47 +09:00
.get_maintainer.ignore Add Jeff Kirsher to .get_maintainer.ignore 2024-03-08 11:36:54 +00:00
.gitattributes .gitattributes: set diff driver for Rust source code files 2023-05-31 17:48:25 +02:00
.gitignore kbuild: create a list of all built DTB files 2024-02-19 18:20:39 +09:00
.mailmap MAINTAINERS: change vmware.com addresses to broadcom.com 2024-04-05 11:21:31 -07:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS Not a ton of stuff happening in the clk framework in this pull request. We got 2024-03-15 11:48:01 -07:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS Devicetree fixes for v6.9, part 1: 2024-04-05 14:07:22 -07:00
Makefile Linux 6.9-rc3 2024-04-07 13:22:46 -07:00
README README: Fix spelling 2024-03-18 03:36:32 -06:00

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

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.

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.