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* rcu: Remove RCU_NONIDLE()Peter Zijlstra2023-05-112-36/+1
| | | | | | | | | | | | Since there are now exactly _zero_ users of RCU_NONIDLE(), make it go away before someone else decides to (ab)use it. [ paulmck: Remove extraneous whitespace. ] Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Acked-by: Mark Rutland <mark.rutland@arm.com> Acked-by: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* doc: Update whatisRCU.rstUladzislau Rezki (Sony)2023-04-051-3/+3
| | | | | | | | | | The kfree_rcu() macro is deprecated. Rename it to its new kfree_rcu_mightsleep() name in this documentation. Acked-by: Joel Fernandes (Google) <joel@joelfernandes.org> Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
* Documentation: RCU: Correct spellingRandy Dunlap2023-04-056-14/+14
| | | | | | | | | | | | | | | | | | | | | Correct spelling problems for Documentation/RCU/ as reported by codespell. Note: in RTFP.txt, there are other misspellings that are left as is since they were used that way in email Subject: lines or in LWN.net articles. [preemptable, Preemptable, synchonisation] Acked-by: Joel Fernandes (Google) <joel@joelfernandes.org> Signed-off-by: Randy Dunlap <rdunlap@infradead.org> Cc: Jonathan Corbet <corbet@lwn.net> Cc: linux-doc@vger.kernel.org Cc: "Paul E. McKenney" <paulmck@kernel.org> Cc: Frederic Weisbecker <frederic@kernel.org> Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com> Cc: Josh Triplett <josh@joshtriplett.org> Cc: rcu@vger.kernel.org Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
* Documentation/RCU: s/not/note/ in checklist.rstQiuxu Zhuo2023-04-051-1/+1
| | | | | | | | | | "Please not that you *cannot* rely..." has a typo. Fix it. Acked-by: Joel Fernandes (Google) <joel@joelfernandes.org> Signed-off-by: Qiuxu Zhuo <qiuxu.zhuo@intel.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
* doc: Fix htmldocs build warnings of stallwarn.rstZhen Lei2023-01-051-26/+30
| | | | | | | | | | | | | | | | | | | | | | Documentation/RCU/stallwarn.rst: 401: WARNING: Literal block expected; none found. 428: WARNING: Literal block expected; none found. 445: WARNING: Literal block expected; none found. 459: WARNING: Literal block expected; none found. 468: WARNING: Literal block expected; none found. The literal block needs to be indented, so this commit adds two spaces to each line. In addition, ':', which is used as a boundary in the literal block, is replaced by '|'. Link: https://lore.kernel.org/linux-next/20221123163255.48653674@canb.auug.org.au/ Fixes: 3d2788ba4573 ("doc: Document CONFIG_RCU_CPU_STALL_CPUTIME=y stall information") Reported-by: Stephen Rothwell <sfr@canb.auug.org.au> Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com> Tested-by: Akira Yokosawa <akiyks@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* docs/RCU/rcubarrier: Right-adjust line numbers in code snippetsAkira Yokosawa2023-01-051-84/+84
| | | | | | | | | | | | | | | | | | | Line numbers in code snippets in rcubarrier.rst have beed left adjusted since commit 4af498306ffd ("doc: Convert to rcubarrier.txt to ReST"). This might have been because right adjusting them had confused Sphinx. The rules around a literal block in reST are: - Need a blank line above it. - A line with the same indent level as the line above it is regarded as the end of it. Those line numbers can be right adjusted by keeping indents at two- digit numbers. While at it, add some spaces between the column of line numbers and the code area for better readability. Signed-off-by: Akira Yokosawa <akiyks@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* docs/RCU/rcubarrier: Adjust 'Answer' parts of QQs as definition-listsAkira Yokosawa2023-01-051-3/+6
| | | | | | | | | | | The "Answer" parts of QQs divert from proper format of definition-lists as described at [1] and are not rendered as such. Adjust them. Link: [1] https://docutils.sourceforge.io/docs/ref/rst/restructuredtext.html#definition-lists Signed-off-by: Akira Yokosawa <akiyks@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* doc: Document CONFIG_RCU_CPU_STALL_CPUTIME=y stall informationZhen Lei2023-01-051-0/+88
| | | | | | | | | | | | This commit documents the additional RCU CPU stall warning output produced by kernels built with CONFIG_RCU_CPU_STALL_CPUTIME=y or booted with rcupdate.rcu_cpu_stall_cputime=1. [ paulmck: Apply wordsmithing. ] Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com> Reviewed-by: Frederic Weisbecker <frederic@kernel.org> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* doc: Update whatisRCU.rstPaul E. McKenney2023-01-051-68/+125
| | | | | | | This commit updates whatisRCU.rst with wordsmithing and updates provokes by the passage of time. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* doc: Update rcu.rst URL to RCU publicationsPaul E. McKenney2023-01-051-1/+2
| | | | | | Also add the more recent thicket of Google Documents. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* doc: Update UP.rstPaul E. McKenney2023-01-051-2/+11
| | | | | | | This commit updates UP.rst to reflect changes over the past few years, including the advent of userspace RCU libraries for constrained systems. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* doc: Update torture.rstPaul E. McKenney2023-01-051-4/+85
| | | | | | | This commit updates torture.rst with wordsmithing and the addition of a few more scripts. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* doc: Update stallwarn.rstPaul E. McKenney2023-01-051-18/+25
| | | | | | | This commit updates stallwarn.rst to reflect RCU additions and changes over the past few years. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* doc: Update rcu.rstPaul E. McKenney2023-01-051-1/+2
| | | | | | | This commit provides a couple of updates based on the inexorable passage of time. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* doc: Update and wordsmith rculist_nulls.rstPaul E. McKenney2023-01-051-55/+54
| | | | | | Do some wordsmithing and breaking up of RCU readers. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* doc: Update rcu_dereference.rstPaul E. McKenney2023-01-041-5/+16
| | | | | | | This commit updates rcu_dereference.rst to reflect RCU additions and changes over the past few years Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* doc: Update rcubarrier.rstPaul E. McKenney2023-01-041-86/+110
| | | | | | | | | This commit updates rcubarrier.txt to reflect RCU additions and changes over the past few years. [ paulmck: Apply Stephen Rothwell feedback. ] Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* doc: Update NMI-RCU.rstPaul E. McKenney2023-01-041-2/+2
| | | | | | | This commit updates NMI-RCU.rst to highlight the ancient heritage of the example code and to discourage wanton compiler "optimizations". Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* doc: Further updates to RCU's lockdep.rstPaul E. McKenney2023-01-041-7/+6
| | | | | | This commit wordsmiths RCU's lockdep.rst. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* Merge tag 'timers-core-2022-12-10' of ↵Linus Torvalds2022-12-121-1/+1
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip Pull timer updates from Thomas Gleixner: "Updates for timers, timekeeping and drivers: Core: - The timer_shutdown[_sync]() infrastructure: Tearing down timers can be tedious when there are circular dependencies to other things which need to be torn down. A prime example is timer and workqueue where the timer schedules work and the work arms the timer. What needs to prevented is that pending work which is drained via destroy_workqueue() does not rearm the previously shutdown timer. Nothing in that shutdown sequence relies on the timer being functional. The conclusion was that the semantics of timer_shutdown_sync() should be: - timer is not enqueued - timer callback is not running - timer cannot be rearmed Preventing the rearming of shutdown timers is done by discarding rearm attempts silently. A warning for the case that a rearm attempt of a shutdown timer is detected would not be really helpful because it's entirely unclear how it should be acted upon. The only way to address such a case is to add 'if (in_shutdown)' conditionals all over the place. This is error prone and in most cases of teardown not required all. - The real fix for the bluetooth HCI teardown based on timer_shutdown_sync(). A larger scale conversion to timer_shutdown_sync() is work in progress. - Consolidation of VDSO time namespace helper functions - Small fixes for timer and timerqueue Drivers: - Prevent integer overflow on the XGene-1 TVAL register which causes an never ending interrupt storm. - The usual set of new device tree bindings - Small fixes and improvements all over the place" * tag 'timers-core-2022-12-10' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (34 commits) dt-bindings: timer: renesas,cmt: Add r8a779g0 CMT support dt-bindings: timer: renesas,tmu: Add r8a779g0 support clocksource/drivers/arm_arch_timer: Use kstrtobool() instead of strtobool() clocksource/drivers/timer-ti-dm: Fix missing clk_disable_unprepare in dmtimer_systimer_init_clock() clocksource/drivers/timer-ti-dm: Clear settings on probe and free clocksource/drivers/timer-ti-dm: Make timer_get_irq static clocksource/drivers/timer-ti-dm: Fix warning for omap_timer_match clocksource/drivers/arm_arch_timer: Fix XGene-1 TVAL register math error clocksource/drivers/timer-npcm7xx: Enable timer 1 clock before use dt-bindings: timer: nuvoton,npcm7xx-timer: Allow specifying all clocks dt-bindings: timer: rockchip: Add rockchip,rk3128-timer clockevents: Repair kernel-doc for clockevent_delta2ns() clocksource/drivers/ingenic-ost: Define pm functions properly in platform_driver struct clocksource/drivers/sh_cmt: Access registers according to spec vdso/timens: Refactor copy-pasted find_timens_vvar_page() helper into one copy Bluetooth: hci_qca: Fix the teardown problem for real timers: Update the documentation to reflect on the new timer_shutdown() API timers: Provide timer_shutdown[_sync]() timers: Add shutdown mechanism to the internal functions timers: Split [try_to_]del_timer[_sync]() to prepare for shutdown mode ...
| * timers: Update the documentation to reflect on the new timer_shutdown() APISteven Rostedt (Google)2022-11-241-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | In order to make sure that a timer is not re-armed after it is stopped before freeing, a new shutdown state is added to the timer code. The API timer_shutdown_sync() and timer_shutdown() must be called before the object that holds the timer can be freed. Update the documentation to reflect this new workflow. [ tglx: Updated to the new semantics and updated the zh_CN version ] Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Tested-by: Guenter Roeck <linux@roeck-us.net> Reviewed-by: Jacob Keller <jacob.e.keller@intel.com> Reviewed-by: Anna-Maria Behnsen <anna-maria@linutronix.de> Link: https://lore.kernel.org/r/20221110064147.712934793@goodmis.org Link: https://lore.kernel.org/r/20221123201625.375284489@linutronix.de
| * Documentation: Replace del_timer/del_timer_sync()Thomas Gleixner2022-11-241-1/+1
| | | | | | | | | | | | | | | | | | | | | | Adjust to the new preferred function names. Suggested-by: Steven Rostedt <rostedt@goodmis.org> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Reviewed-by: Jacob Keller <jacob.e.keller@intel.com> Reviewed-by: Anna-Maria Behnsen <anna-maria@linutronix.de> Link: https://lore.kernel.org/r/20221123201625.075320635@linutronix.de
* | doc: Update RCU's lockdep.rstPaul E. McKenney2022-10-201-0/+4
| | | | | | | | | | | | This commit adds a couple of new functions to the documentation. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* | doc: Update listRCU.rstPaul E. McKenney2022-10-201-71/+103
| | | | | | | | | | | | | | | | | | This commit updates listRCU.txt to reflect RCU additions and changes over the past few years. [ paulmck: Apply kernel test robot feedback. ] Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* | doc: Update checklist.txtPaul E. McKenney2022-10-181-101/+143
| | | | | | | | | | | | | | This commit updates checklist.txt to reflect RCU additions and changes over the past few years. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* | doc: Remove arrayRCU.rstPaul E. McKenney2022-10-182-166/+0
|/ | | | | | | | | | | | | | | | | | | | | Although RCU can in theory be used to protect array indexes in a manner similar to the way it protects pointers, doing so is extremely risky because of the huge number of optimizations that modern compilers can apply to integral types. For but one example, if your code can be configured such that your array contains only a single element, then indexing that array with any integer other than zero invokes undefined behavior, which in turn means that the compiler is within its rights to assume (without checking!) that any integer used as an index to that array has the value zero. Therefore, the compiler can index the array with the constant zero, which breaks any dependencies that might have otherwise existed between the time the actual value was loaded and the time that the array was indexed. This commit therefore removes the arrayRCU.rst file that describes how to go about carrying dependencies through array indexes. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* Merge tag 'docs-6.1' of git://git.lwn.net/linuxLinus Torvalds2022-10-032-2/+2
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Pull documentation updates from Jonathan Corbet: "There's not a huge amount of activity in the docs tree this time around, but a few significant changes even so: - A complete rewriting of the top-level index.rst file, which mostly reflects itself in a redone top page in the HTML-rendered docs. The hope is that the new organization will be a friendlier starting point for both users and developers. - Some math-rendering improvements. - A coding-style.rst update on the use of BUG() and WARN() - A big maintainer-PHP guide update. - Some code-of-conduct updates - More Chinese translation work Plus the usual pile of typo fixes, corrections, and updates" * tag 'docs-6.1' of git://git.lwn.net/linux: (66 commits) checkpatch: warn on usage of VM_BUG_ON() and other BUG variants coding-style.rst: document BUG() and WARN() rules ("do not crash the kernel") Documentation: devres: add missing IO helper Documentation: devres: update IRQ helper Documentation/mm: modify page_referenced to folio_referenced Documentation/CoC: Reflect current CoC interpretation and practices docs/doc-guide: Add documentation on SPHINX_IMGMATH docs: process/5.Posting.rst: clarify use of Reported-by: tag docs, kprobes: Fix the wrong location of Kprobes docs: add a man-pages link to the front page docs: put atomic*.txt and memory-barriers.txt into the core-api book docs: move asm-annotations.rst into core-api docs: remove some index.rst cruft docs: reconfigure the HTML left column docs: Rewrite the front page docs: promote the title of process/index.rst Documentation: devres: add missing SPI helper Documentation: devres: add missing PINCTRL helpers docs: hugetlbpage.rst: fix a typo of hugepage size docs/zh_CN: Add new translation of admin-guide/bootconfig.rst ...
| * Delete duplicate words from kernel docsAkhil Raj2022-09-272-2/+2
| | | | | | | | | | | | | | | | | | | | I have deleted duplicate words like to, guest, trace, when, we Signed-off-by: Akhil Raj <lf32.dev@gmail.com> Link: https://lore.kernel.org/r/20220829065239.4531-1-lf32.dev@gmail.com Signed-off-by: Jonathan Corbet <corbet@lwn.net>
* | doc/rcu: Update LWN article URLs and add 2019 articleShao-Tse Hung2022-08-311-7/+9
| | | | | | | | | | | | | | | | This patch adds LWN articles about RCU APIs which were released in 2019. Also, HTTP URLs are replaced by HTTPS. Signed-off-by: Shao-Tse Hung <ccs100203@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* | doc: SLAB_TYPESAFE_BY_RCU uses cannot rely on spinlocksPaul E. McKenney2022-08-311-7/+12
| | | | | | | | | | | | | | | | | | | | | | | | | | Because the SLAB_TYPESAFE_BY_RCU code does not zero pages that are to be broken up into slabs, the memory returned by kmem_cache_alloc() must be fully initialized, including any spinlocks included in the newly allocated structure. This means that readers attempting to look up an SLAB_TYPESAFE_BY_RCU object must use a reference-counting approach. A spinlock may be acquired only after a reference is obtained, which prevents that object from being passed to kmem_struct_free(), but only while that reference continues to be held. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* | doc: Update rcu_access_pointer() advice in rcu_dereference.rstPaul E. McKenney2022-08-311-4/+10
| | | | | | | | | | | | | | | | | | This commit updates the rcu_access_pointer() advice, noting that its return value should not be assigned to a local variable, and also noting that there is little point in using rcu_access_pointer() within an RCU read-side critical section. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* | doc: Fix list: rcu_access_pointer() is not lockdep-checkedPaul E. McKenney2022-08-311-3/+9
| | | | | | | | | | | | | | | | | | | | | | | | The rcu_access_pointer() macro does not consult lockdep by design because it is intended to be used outside of RCU read-side critical sections. This commit therefore makes a separate list for it in whatisRCU.rst. Similarly, RCU_LOCKDEP_WARN(), rcu_sleep_check(), and RCU_NONIDLE() do not do anything with pointer access. This commit therefore creates a separate utility-API list for them. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* | doc: Use rcu_barrier() to rate-limit RCU callbacksPaul E. McKenney2022-08-311-1/+2
| | | | | | | | | | | | | | | | The checklist.rst document advises periodic synchronize_rcu() invocations to prevent callback flooding. However, rcu_barrier() is often a better choice. This commit therefore adds words to this effect. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* | doc: Call out queue_rcu_work() for blocking RCU callbacksPaul E. McKenney2022-08-311-0/+3
| | | | | | | | | | | | | | | | | | The current checklist.rst file correctly notes that RCU callbacks execute in BH context, and cannot block. This commit adds words advising people needing callbacks to block to use workqueues, for example, by replacing call_rcu() with queue_rcu_work(). Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* | doc: Emphasize the need for explicit RCU read-side markersPaul E. McKenney2022-08-311-2/+7
|/ | | | | | | This commit updates checklist.rst to emphasize the need for explicit markers for RCU read-side critical sections. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* rcu/context-tracking: Remove unused and/or unecessary middle functionsFrederic Weisbecker2022-07-051-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | Some eqs functions are now only used internally by context tracking, so their public declarations can be removed. Also middle functions such as rcu_user_*() and rcu_idle_*() which now directly call to rcu_eqs_enter() and rcu_eqs_exit() can be wiped out as well. Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com> Cc: Uladzislau Rezki <uladzislau.rezki@sony.com> Cc: Joel Fernandes <joel@joelfernandes.org> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Nicolas Saenz Julienne <nsaenz@kernel.org> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Xiongfeng Wang <wangxiongfeng2@huawei.com> Cc: Yu Liao <liaoyu15@huawei.com> Cc: Phil Auld <pauld@redhat.com> Cc: Paul Gortmaker<paul.gortmaker@windriver.com> Cc: Alex Belits <abelits@marvell.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Reviewed-by: Nicolas Saenz Julienne <nsaenzju@redhat.com> Tested-by: Nicolas Saenz Julienne <nsaenzju@redhat.com>
* context_tracking: Take NMI eqs entrypoints over RCUFrederic Weisbecker2022-07-051-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | The RCU dynticks counter is going to be merged into the context tracking subsystem. Prepare with moving the NMI extended quiescent states entrypoints to context tracking. For now those are dumb redirection to existing RCU calls. Acked-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com> Cc: Uladzislau Rezki <uladzislau.rezki@sony.com> Cc: Joel Fernandes <joel@joelfernandes.org> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Nicolas Saenz Julienne <nsaenz@kernel.org> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Xiongfeng Wang <wangxiongfeng2@huawei.com> Cc: Yu Liao <liaoyu15@huawei.com> Cc: Phil Auld <pauld@redhat.com> Cc: Paul Gortmaker<paul.gortmaker@windriver.com> Cc: Alex Belits <abelits@marvell.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Reviewed-by: Nicolas Saenz Julienne <nsaenzju@redhat.com> Tested-by: Nicolas Saenz Julienne <nsaenzju@redhat.com>
* context_tracking: Take IRQ eqs entrypoints over RCUFrederic Weisbecker2022-07-052-7/+7
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | The RCU dynticks counter is going to be merged into the context tracking subsystem. Prepare with moving the IRQ extended quiescent states entrypoints to context tracking. For now those are dumb redirection to existing RCU calls. [ paulmck: Apply Stephen Rothwell feedback from -next. ] [ paulmck: Apply Nathan Chancellor feedback. ] Acked-by: Paul E. McKenney <paulmck@kernel.org> Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com> Cc: Uladzislau Rezki <uladzislau.rezki@sony.com> Cc: Joel Fernandes <joel@joelfernandes.org> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Nicolas Saenz Julienne <nsaenz@kernel.org> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Xiongfeng Wang <wangxiongfeng2@huawei.com> Cc: Yu Liao <liaoyu15@huawei.com> Cc: Phil Auld <pauld@redhat.com> Cc: Paul Gortmaker<paul.gortmaker@windriver.com> Cc: Alex Belits <abelits@marvell.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Reviewed-by: Nicolas Saenz Julienne <nsaenzju@redhat.com> Tested-by: Nicolas Saenz Julienne <nsaenzju@redhat.com>
* context_tracking: Take idle eqs entrypoints over RCUFrederic Weisbecker2022-07-051-2/+2
| | | | | | | | | | | | | | | | | | | | | | | | | | | The RCU dynticks counter is going to be merged into the context tracking subsystem. Start with moving the idle extended quiescent states entrypoints to context tracking. For now those are dumb redirections to existing RCU calls. [ paulmck: Apply kernel test robot feedback. ] Signed-off-by: Frederic Weisbecker <frederic@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Neeraj Upadhyay <quic_neeraju@quicinc.com> Cc: Uladzislau Rezki <uladzislau.rezki@sony.com> Cc: Joel Fernandes <joel@joelfernandes.org> Cc: Boqun Feng <boqun.feng@gmail.com> Cc: Nicolas Saenz Julienne <nsaenz@kernel.org> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Xiongfeng Wang <wangxiongfeng2@huawei.com> Cc: Yu Liao <liaoyu15@huawei.com> Cc: Phil Auld <pauld@redhat.com> Cc: Paul Gortmaker<paul.gortmaker@windriver.com> Cc: Alex Belits <abelits@marvell.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org> Reviewed-by: Nicolas Saenz Julienne <nsaenzju@redhat.com> Tested-by: Nicolas Saenz Julienne <nsaenzju@redhat.com>
* Merge branch 'exp.2022.05.11a' into HEADPaul E. McKenney2022-05-111-0/+20
|\ | | | | | | exp.2022.05.11a: Expedited-grace-period latency-reduction updates.
| * rcu: Introduce CONFIG_RCU_EXP_CPU_STALL_TIMEOUTUladzislau Rezki2022-05-111-0/+20
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Currently both expedited and regular grace period stall warnings use a single timeout value that with units of seconds. However, recent Android use cases problem require a sub-100-millisecond expedited RCU CPU stall warning. Given that expedited RCU grace periods normally complete in far less than a single millisecond, especially for small systems, this is not unreasonable. Therefore introduce the CONFIG_RCU_EXP_CPU_STALL_TIMEOUT kernel configuration that defaults to 20 msec on Android and remains the same as that of the non-expedited stall warnings otherwise. It also can be changed in run-time via: /sys/.../parameters/rcu_exp_cpu_stall_timeout. [ paulmck: Default of zero to use CONFIG_RCU_STALL_TIMEOUT. ] Signed-off-by: Uladzislau Rezki <uladzislau.rezki@sony.com> Signed-off-by: Uladzislau Rezki (Sony) <urezki@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* | docs: Update RCU cross-references as suggested in doc-guideAkira Yokosawa2022-04-218-29/+25
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The RCU documentation contains old-style cross references which do not follow the best practices outlined in doc-guide/sphinx.rst. In addition, some of the cross references use URLs that should be replaced by pathnames. Update all of these cross references and adjust the surrounding words. Summary of changes: - out-of-date plaintext file names (*.txt) -> *.rst - references by :ref: tags -> path names of *.rst * use relative paths to .rst files under the RCU/ subdirectory * use abs paths of Documentation/xxx for other .rst files - references by URL under https://www.kernel.org/ -> paths of *.rst - adjust surrounding words of some of updated references. Note: The automarkup.py script interprets references via "*.txt" as if they were via "*.rst", so the *.txt -> *.rst changes should be regarded as cleanups rather than bug fixes. Cc: rcu@vger.kernel.org Cc: linux-doc@vger.kernel.org Tested-by: Bagas Sanjaya <bagasdotme@gmail.com> Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org> Signed-off-by: Akira Yokosawa <akiyks@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* | docs: Add documentation for rude and trace RCU flavorsPaul E. McKenney2022-04-211-0/+32
|/ | | | | | | | | This commit belatedly adds documentation of Tasks Rude RCU and Tasks Trace RCU to RCU's requirements document. Tested-by: Bagas Sanjaya <bagasdotme@gmail.com> Reviewed-by: Steven Rostedt (Google) <rostedt@goodmis.org> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
*-. Merge branches 'doc.2021.11.30c', 'exp.2021.12.07a', 'fastnohz.2021.11.30c', ↵Paul E. McKenney2021-12-091-11/+0
|\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 'fixes.2021.11.30c', 'nocb.2021.12.09a', 'nolibc.2021.11.30c', 'tasks.2021.12.09a', 'torture.2021.12.07a' and 'torturescript.2021.11.30c' into HEAD doc.2021.11.30c: Documentation updates. exp.2021.12.07a: Expedited-grace-period fixes. fastnohz.2021.11.30c: Remove CONFIG_RCU_FAST_NO_HZ. fixes.2021.11.30c: Miscellaneous fixes. nocb.2021.12.09a: No-CB CPU updates. nolibc.2021.11.30c: Tiny in-kernel library updates. tasks.2021.12.09a: RCU-tasks updates, including update-side scalability. torture.2021.12.07a: Torture-test in-kernel module updates. torturescript.2021.11.30c: Torture-test scripting updates.
| | * rcu: Remove the RCU_FAST_NO_HZ Kconfig optionPaul E. McKenney2021-12-011-11/+0
| |/ | | | | | | | | | | | | | | | | | | | | | | 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 <paulmck@kernel.org>
* | doc: RCU: Avoid 'Symbol' font-family in SVG figuresAkira Yokosawa2021-12-0111-67/+67
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | On Ubuntu Focal, strings in some of SVG files under Documentation/RCU/Design can not be rendered properly when converted to PDF. Ubuntu releases since Focal and Debian bullseye have trouble with "Symbol" font-family in SVG files. As those strings are mostly API names such as "READ_ONCE()", "WRITE_ONCE(), "rcu_read_lock()", and so on, using a generic monospace font-family should be a good alternative. Substitute the font-family name by a simple sed pattern: 's/Symbol/monospace/g' Signed-off-by: Akira Yokosawa <akiyks@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* | doc: Add refcount analogy to What is RCUNeilBrown2021-12-011-8/+82
|/ | | | | | | | | | | | | | | | The reader-writer-lock analogy is a useful way to think about RCU, but it is not always applicable. It is useful to have other analogies to work with, and particularly to emphasise that no single analogy is perfect. This patch add a "RCU as reference count" to the "what is RCU" document. See https://lwn.net/Articles/872559/ [ paulmck: Apply Akira Yokosawa feedback. ] Reviewed-by: Akira Yokosawa <akiyks@gmail.com> Signed-off-by: NeilBrown <neilb@suse.de> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* rcu: Fix undefined Kconfig macrosZhouyi Zhou2021-09-141-37/+32
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Invoking scripts/checkkconfigsymbols.py in the Linux-kernel source tree located the following issues: 1. TREE_PREEMPT_RCU Referencing files: arch/sh/configs/sdk7786_defconfig It should now be CONFIG_PREEMPT_RCU. Except that the CONFIG_PREEMPT=y in that same file implies CONFIG_PREEMPT_RCU=y. Therefore, delete the CONFIG_TREE_PREEMPT_RCU=y line. The reason is as follows: In kernel/rcu/Kconfig, we have config PREEMPT_RCU bool default y if PREEMPTION https://www.kernel.org/doc/Documentation/kbuild/kconfig-language.txt says, "The default value is only assigned to the config symbol if no other value was set by the user (via the input prompt above)." there is no prompt in config PREEMPT_RCU entry, so we are guaranteed to get CONFIG_PREEMPT_RCU=y when CONFIG_PREEMPT is present. 2. RCU_CPU_STALL_INFO Referencing files: arch/xtensa/configs/nommu_kc705_defconfig The old Kconfig option RCU_CPU_STALL_INFO was removed by commit 75c27f119b64 ("rcu: Remove CONFIG_RCU_CPU_STALL_INFO"), and the kernel now acts as if this Kconfig option was unconditionally enabled. 3. RCU_NOCB_CPU_ALL Referencing files: Documentation/RCU/Design/Memory-Ordering/Tree-RCU-Memory-Ordering.rst This is an old snapshot of the code. I update this from the real rcu_prepare_for_idle() function in kernel/rcu/tree_plugin.h. This change was tested by invoking "make htmldocs". 4. RCU_TORTURE_TESTS Referencing files: kernel/rcu/rcutorture.c Forward-progress checking conflicts with CPU-stall testing, so we should complain at "modprobe rcutorture" when both are enabled. Signed-off-by: Zhouyi Zhou <zhouzhouyi@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* doc: Add another stall-warning root cause in stallwarn.rstPaul E. McKenney2021-09-141-0/+10
| | | | | | | | This commit adds a bullet item noting that both deficiencies and surpluses of calls to rcu_*_enter() and rcu_*_exit() can result in RCU CPU stall warnings. Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
* doc: Update stallwarn.rst with recent changesPaul E. McKenney2021-07-201-6/+15
| | | | | | | | This commit calls out the possibility of self-detected stalls, adds new messages, and calls out the use for stack traces. Reported-by: Jeff Layton <jlayton@kernel.org> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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