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2020-01-24Merge branches 'doc.2019.12.10a', 'exp.2019.12.09a', 'fixes.2020.01.24a', ↵Paul E. McKenney
'kfree_rcu.2020.01.24a', 'list.2020.01.10a', 'preempt.2020.01.24a' and 'torture.2019.12.09a' into HEAD doc.2019.12.10a: Documentations updates exp.2019.12.09a: Expedited grace-period updates fixes.2020.01.24a: Miscellaneous fixes kfree_rcu.2020.01.24a: Batch kfree_rcu() work list.2020.01.10a: RCU-protected-list updates preempt.2020.01.24a: Preemptible RCU updates torture.2019.12.09a: Torture-test updates
2020-01-24rcu: Remove kfree_rcu() special casing and lazy-callback handlingJoel Fernandes (Google)
This commit removes kfree_rcu() special-casing and the lazy-callback handling from Tree RCU. It moves some of this special casing to Tiny RCU, the removal of which will be the subject of later commits. This results in a nice negative delta. Suggested-by: Paul E. McKenney <paulmck@linux.ibm.com> Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> [ paulmck: Add slab.h #include, thanks to kbuild test robot <lkp@intel.com>. ] Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2019-12-10doc: Fix typo "deference" to "dereference"Paul E. McKenney
Reported-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2019-12-10doc: Updated full list of RCU API in whatisRCU.rstMadhuparna Bhowmik
This patch updates the list of RCU API in whatisRCU.rst. Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmik04@gmail.com> Tested-by: Amol Grover <frextrite@gmail.com> Tested-by: Phong Tran <tranmanphong@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2019-12-10doc: Convert to rcubarrier.txt to ReSTAmol Grover
Convert rcubarrier.txt to rcubarrier.rst and add it to index.rst. Format file according to reST - Add headings and sub-headings - Add code segments - Add cross-references to quizes and answers Signed-off-by: Amol Grover <frextrite@gmail.com> Tested-by: Phong Tran <tranmanphong@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2019-12-10doc: Convert to rcu_dereference.txt to rcu_dereference.rstAmol Grover
This patch converts rcu_dereference.txt to rcu_dereference.rst and adds it to index.rst Signed-off-by: Amol Grover <frextrite@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2019-12-10doc: Convert whatisRCU.txt to .rstPhong Tran
This commit updates whatisRCU.txt to the new .rst format. This change includes: - Formatting bullet lists - Adding literal blocks - Links from table of contents to corresponding sections - Links to external documents - Reformat quick quizzes Signed-off-by: Phong Tran <tranmanphong@gmail.com> Tested-by: Madhuparna Bhowmik <madhuparnabhowmik04@gmail.com> [ tranmanphong: Apply Amol Grover feedback. ] Reviewed-by: Amol Grover <frextrite@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2019-12-10doc: Converted NMI-RCU.txt to NMI-RCU.rst.Madhuparna Bhowmik
This patch converts NMI-RCU from txt to rst format. Also adds NMI-RCU in the index.rst file. Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmik04@gmail.com> [ paulmck: Apply feedback from Phong Tran. ] Tested-by: Phong Tran <tranmanphong@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2019-12-10doc: Convert arrayRCU.txt to arrayRCU.rstMadhuparna Bhowmik
This patch converts arrayRCU from .txt to .rst format, and also adds it to the index.rst file. Signed-off-by: Madhuparna Bhowmik <madhuparnabhowmik04@gmail.com> [ paulmck: Trimmed trailing whitespace. ] Tested-by: Phong Tran <tranmanphong@gmail.com> Tested-by: Amol Grover <frextrite@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2019-10-29Documentation: Rename rcu_node_context_switch() to rcu_note_context_switch()Sebastian Andrzej Siewior
While Paul was explaining some RCU magic I noticed a typo in rcu_note_context_switch(). As a result, this commit replaces rcu_node_context_switch() with rcu_note_context_switch(). Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2019-10-29doc: Update list_for_each_entry_rcu() documentationJoel Fernandes (Google)
This commit updates the documentation with information about usage of lockdep with list_for_each_entry_rcu(). Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> [ paulmck: Wordsmithing. ] Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2019-10-29Restore docs "rcu: Restore barrier() to rcu_read_lock() and rcu_read_unlock()"Joel Fernandes (Google)
This restores docs back in ReST format. Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> [ paulmck: Added Joel's SoB per Stephen Rothwell feedback. ] [ paulmck: Joel approved via private email. ] Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2019-10-29Restore docs "treewide: Rename rcu_dereference_raw_notrace() to _check()"Joel Fernandes (Google)
This restores docs back in ReST format. Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> [ paulmck: Added Joel's SoB per Stephen Rothwell feedback. ] [ paulmck: Joel approved via private email. ] Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2019-10-29docs: rcu: Increase toctree to 3Joel Fernandes (Google)
These documents are long and have various sections. Provide a good toc nesting level. Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2019-10-29docs: rcu: Correct links referring to titlesJoel Fernandes (Google)
Mauro's auto conversion broken these links, fix them. Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2019-10-29docs: rcu: convert some articles from html to ReSTMauro Carvalho Chehab
There are 4 RCU articles that are written on html format. The way they are, they can't be part of the Linux Kernel documentation body nor share the styles and pdf output. So, convert them to ReST format. This way, make htmldocs and make pdfdocs will produce a documentation output that will be like the original ones, but will be part of the Linux Kernel documentation body. Part of the conversion was done with the help of pandoc, but the result had some broken things that had to be manually fixed. Following are manual changes Mauro made when doing the automatic conversion: Quoting from: https://lore.kernel.org/rcu/20190726154550.5eeae294@coco.lan/ > > At least the pandoc's version I used here has a bug: its conversion > > from html to ReST on those files only start after a <body> tag - or > > when the first quiz table starts. I only discovered that adding a > > <body> at the beginning of the file solve this book at the last > > conversions. > > > > So, for most html->ReST conversions, I manually converted the first > > part of the document, basically stripping html paragraph tags and > > by replacing highlights by the ReST syntax. > > > > Also, all the quiz tables seem to assume some javascript macro or > > css style that would be hiding the answer part until the mouse moves > > to it. Such macro/css was not there at the kernel tree. So, the quiz > > answers have the same color as the background, making them invisible. > > Even if we had such macro/css, this is not portable for pdf/LaTeX output > > (and I'm not sure if this would work with ePub). > > > > So, I ended by manually doing the table conversion. > > > > Finally, I double-checked if the conversions ended ok, addressing any > > issues that might have heppened. > > > > So, after both automatic conversion and manual fixes, I opened both the > > html files produced by Sphinx and the original ones and compared them > > line per line (except for the indexes, as Sphinx produces them > > automatically), in order to see if all information from the original > > files will be there on a format close to what we have on other ReST > > files, fixing any pending issues if any. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2019-10-29Revert docs from "treewide: Rename rcu_dereference_raw_notrace() to _check()"Joel Fernandes (Google)
This reverts docs from commit 355e9972da81e803bbb825b76106ae9b358caf8e. Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> [ paulmck: Added Joel's SoB per Stephen Rothwell feedback. ] [ paulmck: Joel approved via private email. ] Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2019-10-29Revert docs from "rcu: Restore barrier() to rcu_read_lock() and ↵Joel Fernandes (Google)
rcu_read_unlock()" This reverts docs from commit d6b9cd7dc8e041ee83cb1362fce59a3cdb1f2709. Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> [ paulmck: Added Joel's SoB per Stephen Rothwell feedback. ] [ paulmck: Joel approved via private email. ] Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
2019-08-13Merge branches 'consolidate.2019.08.01b', 'fixes.2019.08.12a', ↵Paul E. McKenney
'lists.2019.08.13a' and 'torture.2019.08.01b' into HEAD consolidate.2019.08.01b: Further consolidation cleanups fixes.2019.08.12a: Miscellaneous fixes lists.2019.08.13a: Optional lockdep arguments for RCU list macros torture.2019.08.01b: Torture-test updates
2019-08-01treewide: Rename rcu_dereference_raw_notrace() to _check()Joel Fernandes (Google)
The rcu_dereference_raw_notrace() API name is confusing. It is equivalent to rcu_dereference_raw() except that it also does sparse pointer checking. There are only a few users of rcu_dereference_raw_notrace(). This patches renames all of them to be rcu_dereference_raw_check() with the "_check()" indicating sparse checking. Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> [ paulmck: Fix checkpatch warnings about parentheses. ] Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-08-01doc: Add rcutree.kthread_prio pointer to stallwarn.txtPaul E. McKenney
This commit adds mention of the rcutree.kthread_prio kernel boot parameter to the discussion of how high-priority real-time tasks can result in RCU CPU stall warnings. (However, this does not necessarily help when the high-priority real-time tasks are using dubious deadlines.) Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-08-01rcu: Restore barrier() to rcu_read_lock() and rcu_read_unlock()Paul E. McKenney
Commit bb73c52bad36 ("rcu: Don't disable preemption for Tiny and Tree RCU readers") removed the barrier() calls from rcu_read_lock() and rcu_write_lock() in CONFIG_PREEMPT=n&&CONFIG_PREEMPT_COUNT=n kernels. Within RCU, this commit was OK, but it failed to account for things like get_user() that can pagefault and that can be reordered by the compiler. Lack of the barrier() calls in rcu_read_lock() and rcu_read_unlock() can cause these page faults to migrate into RCU read-side critical sections, which in CONFIG_PREEMPT=n kernels could result in too-short grace periods and arbitrary misbehavior. Please see commit 386afc91144b ("spinlocks and preemption points need to be at least compiler barriers") and Linus's commit 66be4e66a7f4 ("rcu: locking and unlocking need to always be at least barriers"), this last of which restores the barrier() call to both rcu_read_lock() and rcu_read_unlock(). This commit removes barrier() calls that are no longer needed given that the addition of them in Linus's commit noted above. The combination of this commit and Linus's commit effectively reverts commit bb73c52bad36 ("rcu: Don't disable preemption for Tiny and Tree RCU readers"). Reported-by: Herbert Xu <herbert@gondor.apana.org.au> Reported-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com> [ paulmck: Fix embarrassing typo located by Alan Stern. ]
2019-07-17docs: fix broken doc references due to renamesMauro Carvalho Chehab
Some files got renamed but probably due to some merge conflicts, a few references still point to the old locations. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org>
2019-07-09Merge tag 'docs-5.3' of git://git.lwn.net/linuxLinus Torvalds
Pull Documentation updates from Jonathan Corbet: "It's been a relatively busy cycle for docs: - A fair pile of RST conversions, many from Mauro. These create more than the usual number of simple but annoying merge conflicts with other trees, unfortunately. He has a lot more of these waiting on the wings that, I think, will go to you directly later on. - A new document on how to use merges and rebases in kernel repos, and one on Spectre vulnerabilities. - Various improvements to the build system, including automatic markup of function() references because some people, for reasons I will never understand, were of the opinion that :c:func:``function()`` is unattractive and not fun to type. - We now recommend using sphinx 1.7, but still support back to 1.4. - Lots of smaller improvements, warning fixes, typo fixes, etc" * tag 'docs-5.3' of git://git.lwn.net/linux: (129 commits) docs: automarkup.py: ignore exceptions when seeking for xrefs docs: Move binderfs to admin-guide Disable Sphinx SmartyPants in HTML output doc: RCU callback locks need only _bh, not necessarily _irq docs: format kernel-parameters -- as code Doc : doc-guide : Fix a typo platform: x86: get rid of a non-existent document Add the RCU docs to the core-api manual Documentation: RCU: Add TOC tree hooks Documentation: RCU: Rename txt files to rst Documentation: RCU: Convert RCU UP systems to reST Documentation: RCU: Convert RCU linked list to reST Documentation: RCU: Convert RCU basic concepts to reST docs: filesystems: Remove uneeded .rst extension on toctables scripts/sphinx-pre-install: fix out-of-tree build docs: zh_CN: submitting-drivers.rst: Remove a duplicated Documentation/ Documentation: PGP: update for newer HW devices Documentation: Add section about CPU vulnerabilities for Spectre Documentation: platform: Delete x86-laptop-drivers.txt docs: Note that :c:func: should no longer be used ...
2019-06-28doc: RCU callback locks need only _bh, not necessarily _irqJiunn Chang
The UP.rst file calls for locks acquired within RCU callback functions to use _irq variants (spin_lock_irqsave() or similar), which does work, but can be overkill. This commit therefore instead calls for _bh variants (spin_lock_bh() or similar), while noting that _irq does work. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com> Signed-off-by: Jiunn Chang <c0d1n61at3@gmail.com> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2019-06-27Documentation: RCU: Add TOC tree hooksJiunn Chang
Add TOC tree hooks for: - rcu - listRCU - UP Signed-off-by: Jiunn Chang <c0d1n61at3@gmail.com> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2019-06-27Documentation: RCU: Rename txt files to rstJiunn Chang
Rename the following files to reST: - rcu.txt - listRCU.txt - UP.txt Signed-off-by: Jiunn Chang <c0d1n61at3@gmail.com> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2019-06-27Documentation: RCU: Convert RCU UP systems to reSTJiunn Chang
RCU UP systems reST markup. Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org> Signed-off-by: Jiunn Chang <c0d1n61at3@gmail.com> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2019-06-27Documentation: RCU: Convert RCU linked list to reSTJiunn Chang
RCU linked list reST markup. Signed-off-by: Jiunn Chang <c0d1n61at3@gmail.com> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2019-06-27Documentation: RCU: Convert RCU basic concepts to reSTJiunn Chang
RCU basic concepts reST markup. Reviewed-by: Joel Fernandes (Google) <joel@joelfernandes.org> Signed-off-by: Jiunn Chang <c0d1n61at3@gmail.com> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2019-06-19Merge branches 'consolidate.2019.05.28a', 'doc.2019.05.28a', ↵Paul E. McKenney
'fixes.2019.06.13a', 'srcu.2019.05.28a', 'sync.2019.05.28a' and 'torture.2019.05.28a' into HEAD consolidate.2019.05.28a: RCU flavor consolidation cleanups and optmizations. doc.2019.05.28a: Documentation updates. fixes.2019.06.13a: Miscellaneous fixes. srcu.2019.05.28a: SRCU updates. sync.2019.05.28a: RCU-sync flavor consolidation. torture.2019.05.28a: Torture-test updates.
2019-06-13rcu: Don't return a value from rcu_assign_pointer()Andrea Parri
Quoting Paul [1]: "Given that a quick (and perhaps error-prone) search of the uses of rcu_assign_pointer() in v5.1 didn't find a single use of the return value, let's please instead change the documentation and implementation to eliminate the return value." [1] https://lkml.kernel.org/r/20190523135013.GL28207@linux.ibm.com Signed-off-by: Andrea Parri <andrea.parri@amarulasolutions.com> Cc: "Paul E. McKenney" <paulmck@linux.ibm.com> Cc: Josh Triplett <josh@joshtriplett.org> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com> Cc: Lai Jiangshan <jiangshanlai@gmail.com> Cc: Joel Fernandes <joel@joelfernandes.org> Cc: rcu@vger.kernel.org Cc: Peter Zijlstra <peterz@infradead.org> Cc: Will Deacon <will.deacon@arm.com> Cc: Mark Rutland <mark.rutland@arm.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Sasha Levin <sashal@kernel.org> Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-05-28doc: Fixup definition of rcupdate.rcu_task_stall_timeoutZhenzhong Duan
A positive value of rcupdate.rcu_task_stall_timeout is an interval in seconds rather than jiffies. Signed-off-by: Zhenzhong Duan <zhenzhong.duan@oracle.com> Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-05-28doc/rcuref: Document real world examples in kernelJoel Fernandes (Google)
Document similar real world examples in the kernel corresponding to the second and third code snippets. Also correct an issue in release_referenced() in the code snippet example. Cc: oleg@redhat.com Cc: jannh@google.com Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> [ paulmck: Do a bit of wordsmithing. ] Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-03-26doc: Fix typos and otherwise modernize checklist.txtPaul E. McKenney
This commit fixes some issues with Documentation/RCU/checklist.txt. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-03-26doc: Describe choice of rcu_dereference() APIs and __rcu usagePaul E. McKenney
Reported-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-03-26doc: Repair some whitespace damageTycho Andersen
A diagram in whatisRCU.txt has space character before tabs. This commit therefore makes this diagram consistent with elsewhere in the document: Use one leading tab, followed by spaces for any additional whitespace required. Signed-off-by: Tycho Andersen <tycho@tycho.ws> Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-03-26doc: Remove obsolete RCU update functions from RCU documentationPaul E. McKenney
Now that synchronize_rcu_bh, synchronize_rcu_bh_expedited, call_rcu_bh, rcu_barrier_bh, synchronize_sched, synchronize_sched_expedited, call_rcu_sched, rcu_barrier_sched, get_state_synchronize_sched, and cond_synchronize_sched are obsolete, let's remove them from the documentation aside from a small historical section. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-03-09Merge tag 'docs-5.1' of git://git.lwn.net/linuxLinus Torvalds
Pull documentation updates from Jonathan Corbet: "A fairly routine cycle for docs - lots of typo fixes, some new documents, and more translations. There's also some LICENSES adjustments from Thomas" * tag 'docs-5.1' of git://git.lwn.net/linux: (74 commits) docs: Bring some order to filesystem documentation Documentation/locking/lockdep: Drop last two chars of sample states doc: rcu: Suspicious RCU usage is a warning docs: driver-api: iio: fix errors in documentation Documentation/process/howto: Update for 4.x -> 5.x versioning docs: Explicitly state that the 'Fixes:' tag shouldn't split lines doc: security: Add kern-doc for lsm_hooks.h doc: sctp: Merge and clean up rst files Docs: Correct /proc/stat path scripts/spdxcheck.py: fix C++ comment style detection doc: fix typos in license-rules.rst Documentation: fix admin-guide/README.rst minimum gcc version requirement doc: process: complete removal of info about -git patches doc: translations: sync translations 'remove info about -git patches' perf-security: wrap paragraphs on 72 columns perf-security: elaborate on perf_events/Perf privileged users perf-security: document collected perf_events/Perf data categories perf-security: document perf_events/Perf resource control sysfs.txt: add note on available attribute macros docs: kernel-doc: typo "if ... if" -> "if ... is" ...
2019-03-04Documentation/locking/lockdep: Drop last two chars of sample statesGeert Uytterhoeven
Since the removal of FS_RECLAIM annotations, lockdep states contain four characters, not six. Fixes: e5684bbfc3f03480 ("Documentation/locking/lockdep: Update info about states") Fixes: d92a8cfcb37ecd13 ("locking/lockdep: Rework FS_RECLAIM annotation") Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> Acked-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2019-03-04doc: rcu: Suspicious RCU usage is a warningGeert Uytterhoeven
Suspicious RCU usage messages are reported as warnings. Fixes: a5dd63efda3d07b5 ("lockdep: Use "WARNING" tag on lockdep splats") Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be> Reviewed-by: Paul E. McKenney <paulmck@linux.ibm.com> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2019-02-09Merge branches 'doc.2019.01.26a', 'fixes.2019.01.26a', 'sil.2019.01.26a', ↵Paul E. McKenney
'spdx.2019.02.09a', 'srcu.2019.01.26a' and 'torture.2019.01.26a' into HEAD doc.2019.01.26a: Documentation updates. fixes.2019.01.26a: Miscellaneous fixes. sil.2019.01.26a: Removal of a few more spin_is_locked() instances. spdx.2019.02.09a: Add SPDX identifiers to RCU files srcu.2019.01.26a: SRCU updates. torture.2019.01.26a: Torture-test updates.
2019-01-25RCU/torture.txt: Remove section MODULE PARAMETERSJunchang Wang
The supported module parameters are detailed in both RCU/torture.txt and admin-guide/kernel-parameters.txt, and the latter is actively maintained. So this patch removes section MODULE PARAMETERS in torture.txt and adds a reference to the information in kernel-parameters.txt. Signed-off-by: Junchang Wang <junchangwang@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com> [ paulmck: Add search string. ]
2019-01-25rcu: Rename rcu_process_callbacks() to rcu_core() for Tree RCUPaul E. McKenney
Although the name rcu_process_callbacks() still makes sense for Tiny RCU, where most of what it does is invoke callbacks, it no longer makes much sense for Tree RCU, especially given that the actually callback invocation is relegated to rcu_do_batch(), or, for no-CBs CPUs, to the rcuo kthreads. Especially in the latter case, rcu_process_callbacks() has very little to do with actual callbacks. A better description of this function is that it performs RCU's core processing. This commit therefore changes the name of Tree RCU's rcu_process_callbacks() function to rcu_core(), which also has the virtue of being consistent with the existing invoke_rcu_core() function. While in the area, the header comment is reworked. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-01-25rcu: Rename rcu_check_callbacks() to rcu_sched_clock_irq()Paul E. McKenney
The name rcu_check_callbacks() arguably made sense back in the early 2000s when RCU was quite a bit simpler than it is today, but it has become quite misleading, especially with the advent of dyntick-idle and NO_HZ_FULL. The rcu_check_callbacks() function is RCU's hook into the scheduling-clock interrupt, and is now but one of many ways that callbacks get promoted to invocable state. This commit therefore changes the name to rcu_sched_clock_irq(), which is the same number of characters and clearly indicates this function's relation to the rest of the Linux kernel. In addition, for the sake of consistency, rcu_flavor_check_callbacks() is also renamed to rcu_flavor_sched_clock_irq(). While in the area, the header comments for both functions are reworked. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-01-25doc: Fix outdated linksJunchang Wang
Fix outdated links in whatisRCU.txt. Signed-off-by: Junchang Wang <junchangwang@gmail.com> Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-01-25doc: CPU-hotplug notifiers cannot invoke synchronize_srcu() or srcu_barrier()Paul E. McKenney
SRCU's synchronize_srcu() may not be invoked from CPU-hotplug notifiers, due to the fact that SRCU grace periods make use of timers and the possibility of timers being temporarily stranded on the outgoing CPU. This stranding of timers means that timers posted to the outgoing CPU will not fire until late in the CPU-hotplug process. The problem is that if a notifier is waiting on an SRCU grace period, that grace period is waiting on a timer, and that timer is stranded on the outgoing CPU, then the notifier will never be awakened, in other words, deadlock has occurred. This same situation of course also prohibits srcu_barrier() from being invoked from CPU-hotplug notifiers. This commit therefore updates the requirements to include this restriction. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-01-25rcu: Discard separate per-CPU callback countsPaul E. McKenney
Back when there were multiple flavors of RCU, it was necessary to separately count lazy and non-lazy callbacks for each CPU. These counts were used in CONFIG_RCU_FAST_NO_HZ kernels to determine how long a newly idle CPU should be allowed to sleep before handling its RCU callbacks. But now that there is only one flavor, the callback counts for a given CPU's sole rcu_data structure are the counts for that CPU. This commit therefore removes the rcu_data structure's ->nonlazy_posted and ->nonlazy_posted_snap fields, the rcu_idle_count_callbacks_posted() and rcu_cpu_has_callbacks() functions, repurposes the rcu_data structure's ->all_lazy field to record the laziness state at the beginning of the latest idle sojourn, and modifies CONFIG_RCU_FAST_NO_HZ RCU CPU stall warnings accordingly. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2019-01-25rcu: Determine expedited-GP IPI handler at build timePaul E. McKenney
Back when there could be multiple RCU flavors running in the same kernel at the same time, it was necessary to specify the expedited grace-period IPI handler at runtime. Now that there is only one RCU flavor, the IPI handler can be determined at build time. There is therefore no longer any reason for the RCU-preempt and RCU-sched IPI handlers to have different names, nor is there any reason to pass these handlers in function arguments and in the data structures enclosing workqueues. This commit therefore makes all these changes, pushing the specification of the expedited grace-period IPI handler down to the point of use. Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>
2018-11-12doc: Fix "struction" typo in RCU memory-ordering documentationJoel Fernandes (Google)
This commit replaces "struction" with the correct "structure". Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org> Signed-off-by: Paul E. McKenney <paulmck@linux.ibm.com>