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
75c27f119b ("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>
Add some missing critical pieces of explanation to understand the need
for full memory barriers throughout the whole grace period state machine,
thanks to Paul's explanations.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Cc: Neeraj Upadhyay <neeraju@codeaurora.org>
Cc: Joel Fernandes <joel@joelfernandes.org>
Cc: Uladzislau Rezki <urezki@gmail.com>
Cc: Boqun Feng <boqun.feng@gmail.com>
[ paulmck: Adjust code block per Akira Yokosawa. ]
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
The three diagrams describing rcu_gp_init() all spuriously refer to
the same figure, probably due to a copy/paste issue. This commit fixes
these references.
Signed-off-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
The sentence defining the relationship of accesses before a grace
period to read-side accesses following that same grace period was
missing a small word: "not". This commit therefore adds it.
Reported-by: Frederic Weisbecker <frederic@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
During the process of converting the documentation to reST, some links
were converted using the following wrong syntax (and sometimes using %20
instead of spaces):
`Display text <#section-name-in-html>`__
This syntax isn't valid according to the docutils' spec [1], but more
importantly, it is specific to HTML, since it uses '#' to link to an
HTML anchor.
The right syntax would instead use a docutils hyperlink reference as the
embedded URI to point to the section [2], that is:
`Display text <Section Name_>`__
This syntax works in both HTML and PDF.
The LaTeX toolchain doesn't mind the HTML anchor syntax when generating
the pdf documentation (make pdfdocs), that is, the build succeeds but
the links don't work, but that syntax causes errors when trying to build
using the not-yet-merged rst2pdf:
ValueError: format not resolved, probably missing URL scheme or undefined destination target for 'Forcing%20Quiescent%20States'
So, use the correct syntax in order to have it work in all different
output formats.
[1]: https://docutils.sourceforge.io/docs/ref/rst/restructuredtext.html#reference-names
[2]: https://docutils.sourceforge.io/docs/ref/rst/restructuredtext.html#embedded-uris-and-aliases
Fixes: ccc9971e21 ("docs: rcu: convert some articles from html to ReST")
Fixes: c8cce10a62 ("docs: Fix the reference labels in Locking.rst")
Fixes: e548cdeffc ("docs-rst: convert kernel-locking to ReST")
Fixes: 7ddedebb03 ("ALSA: doc: ReSTize writing-an-alsa-driver document")
Signed-off-by: Nícolas F. R. A. Prado <nfraprado@protonmail.com>
Reviewed-by: Takashi Iwai <tiwai@suse.de>
Reviewed-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Link: https://lore.kernel.org/r/20201228144537.135353-1-nfraprado@protonmail.com
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Commit ccc9971e21 ("docs: rcu: convert some articles from html to
ReST") has converted a few of html RCU docs into ReST files, but a few
of html tags which not supported on rst is remaining. This commit
converts those to ReST appropriate alternatives.
Reviewed-by: Madhuparna Bhowmik <madhuparnabhowmik04@gmail.com>
Signed-off-by: SeongJae Park <sjpark@amazon.de>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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>
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>
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>
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>
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>
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>
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>
This commit provides text and diagrams showing how Tree RCU implements
its grace-period memory ordering guarantees.
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
