kernel/linux.git/Documentation/timers, branch v6.18.21

timers/Documentation: Cleanup delay/sleep documentation

2024-10-15T22:36:48+00:00

The documentation which tries to give advices how to properly inserting delays or sleeps is outdated. The file name is 'timers-howto.rst' which might be misleading as it is only about delay and sleep mechanisms and not how to use timers. Update the documentation by integrating the important parts from the related function descriptions and move it all into a self explaining file with the name "delay_sleep_functions.rst". Signed-off-by: Anna-Maria Behnsen Signed-off-by: Thomas Gleixner Reviewed-by: Frederic Weisbecker Link: https://lore.kernel.org/all/20241014-devel-anna-maria-b4-timers-flseep-v3-15-dc8b907cb62f@linutronix.de

treewide: Fix wrong singular form of jiffies in comments

2024-09-08T18:47:40+00:00

There are several comments all over the place, which uses a wrong singular form of jiffies. Replace 'jiffie' by 'jiffy'. No functional change. Signed-off-by: Anna-Maria Behnsen Signed-off-by: Thomas Gleixner Acked-by: Geert Uytterhoeven # m68k Link: https://lore.kernel.org/all/20240904-devel-anna-maria-b4-timers-flseep-v1-3-e98760256370@linutronix.de

sched/isolation: Prevent boot crash when the boot CPU is nohz_full

2024-04-28T08:07:12+00:00

Documentation/timers/no_hz.rst states that the "nohz_full=" mask must not include the boot CPU, which is no longer true after: 08ae95f4fd3b ("nohz_full: Allow the boot CPU to be nohz_full"). However after: aae17ebb53cd ("workqueue: Avoid using isolated cpus' timers on queue_delayed_work") the kernel will crash at boot time in this case; housekeeping_any_cpu() returns an invalid CPU number until smp_init() brings the first housekeeping CPU up. Change housekeeping_any_cpu() to check the result of cpumask_any_and() and return smp_processor_id() in this case. This is just the simple and backportable workaround which fixes the symptom, but smp_processor_id() at boot time should be safe at least for type == HK_TYPE_TIMER, this more or less matches the tick_do_timer_boot_cpu logic. There is no worry about cpu_down(); tick_nohz_cpu_down() will not allow to offline tick_do_timer_cpu (the 1st online housekeeping CPU). Fixes: aae17ebb53cd ("workqueue: Avoid using isolated cpus' timers on queue_delayed_work") Reported-by: Chris von Recklinghausen Signed-off-by: Oleg Nesterov Signed-off-by: Thomas Gleixner Signed-off-by: Ingo Molnar Reviewed-by: Phil Auld Acked-by: Frederic Weisbecker Link: https://lore.kernel.org/r/20240411143905.GA19288@redhat.com Closes: https://lore.kernel.org/all/20240402105847.GA24832@redhat.com/

Documentation: use capitalization for chapters and acronyms

2023-05-16T18:49:31+00:00

Use capital letters in acronyms for CD-ROM, FPGA, and PCMCIA. Use capital letter in the first word of chapter headings for Locking, Timers, and "Brief tutorial on CRC computation". Signed-off-by: Randy Dunlap Cc: Moritz Fischer Cc: Wu Hao Cc: Tom Rix Cc: Peter Zijlstra Cc: Ingo Molnar Cc: Will Deacon Cc: Waiman Long Cc: Boqun Feng Cc: Dominik Brodowski Cc: Thomas Gleixner Acked-by: Xu Yilun Reviewed-by: Phillip Potter Link: https://lore.kernel.org/r/20230516001518.14514-1-rdunlap@infradead.org Signed-off-by: Jonathan Corbet

Documentation: timers: hrtimers: Make hybrid union historical

2023-05-02T16:49:58+00:00

Non-scalar time was removed from the ktime hybrid union in v3.17, and the union itself followed suit in v4.10. Make it clear that ktime_t is always a 64bit scalar type, to avoid confusing the casual reader. While at it, fix a spelling mistake. Fixes: 24e4a8c3e8868874 ("ktime: Kill non-scalar ktime_t implementation for 2038") Fixes: 2456e855354415bf ("ktime: Get rid of the union") Signed-off-by: Geert Uytterhoeven Reviewed-by: Thomas Gleixner Link: https://lore.kernel.org/r/59250a3d1c2c827b5c1833169a6e652ca6a784e6.1683021785.git.geert+renesas@glider.be Signed-off-by: Jonathan Corbet

Documentation: Replace del_timer/del_timer_sync()

2022-11-24T14:09:11+00:00

Adjust to the new preferred function names. Suggested-by: Steven Rostedt Signed-off-by: Thomas Gleixner Reviewed-by: Jacob Keller Reviewed-by: Anna-Maria Behnsen Link: https://lore.kernel.org/r/20221123201625.075320635@linutronix.de

rcu: Remove the RCU_FAST_NO_HZ Kconfig option

2021-12-01T01:24:47+00:00

All of the uses of CONFIG_RCU_FAST_NO_HZ=y that I have seen involve systems with RCU callbacks offloaded. In this situation, all that this Kconfig option does is slow down idle entry/exit with an additional allways-taken early exit. If this is the only use case, then this Kconfig option nothing but an attractive nuisance that needs to go away. This commit therefore removes the RCU_FAST_NO_HZ Kconfig option. Signed-off-by: Paul E. McKenney

Documentation/no_hz: Introduce "dyntick-idle mode" before using it

2021-09-27T17:31:11+00:00

The CONFIG_NO_HZ_IDLE paragraph is using "dyntick-idle mode" before having defined it while the definition comes a couple of paragraphs later. That is leaving the reader with scratching head what that dyntick-idle mode might be. Pull its definition up so that it is clear. Signed-off-by: Borislav Petkov Link: https://lore.kernel.org/r/20210914203355.21360-1-bp@alien8.de Signed-off-by: Jonathan Corbet

Documentation: drop optional BOMs

2021-05-10T21:17:34+00:00

A few of the Documentation .rst files begin with a Unicode byte order mark (BOM). The BOM may signify endianess for 16-bit or 32-bit encodings or indicate that the text stream is indeed Unicode. We don't need it for either of those uses. It may also interfere with (confuse) some software. Since we don't need it and its use is optional, just delete the uses of it in Documentation/. https://en.wikipedia.org/wiki/Byte_order_mark Signed-off-by: Randy Dunlap Reviewed-by: Matthew Wilcox (Oracle) Reviewed-by: Greg Kroah-Hartman Cc: Mauro Carvalho Chehab Link: https://lore.kernel.org/r/20210506231907.14359-1-rdunlap@infradead.org Signed-off-by: Jonathan Corbet

Documentation: Replace lkml.org links with lore

2021-01-11T19:47:38+00:00

Replace the lkml.org links with lore to better use a single source that's more likely to stay available long-term. Done by bash script: cvt_lkml_to_lore () { tmpfile=$(mktemp ./.cvt_links.XXXXXXX) header=$(echo $1 | sed 's@/lkml/@/lkml/headers/@') wget -qO - $header > $tmpfile if [[ $? == 0 ]] ; then link=$(grep -i '^Message-Id:' $tmpfile | head -1 | \ sed -r -e 's/^\s*Message-Id:\s*<\s*//' -e 's/\s*>\s*$//' -e 's@^@https://lore.kernel.org/r/@') # echo "testlink: $link" if [ -n "$link" ] ; then wget -qO - $link > /dev/null if [[ $? == 0 ]] ; then echo $link fi fi fi rm -f $tmpfile } git grep -P -o "\bhttps?://(?:www.)?lkml.org/lkml[\/\w]+" $@ | while read line ; do echo $line file=$(echo $line | cut -f1 -d':') link=$(echo $line | cut -f2- -d':') newlink=$(cvt_lkml_to_lore $link) if [[ -n "$newlink" ]] ; then sed -i -e "s#\b$link\b#$newlink#" $file fi done Link: https://lore.kernel.org/patchwork/patch/1265849/#1462688 Signed-off-by: Joe Perches Link: https://lore.kernel.org/r/77cdb7f32cfb087955bfc3600b86c40bed5d4104.camel@perches.com Signed-off-by: Jonathan Corbet