The [smp_]read_barrier_depends() barrier macros no longer exist as
part of the Linux memory model, so remove all references to them from
the Documentation/ directory.
Although this is fairly mechanical on the whole, we drop the "CACHE
COHERENCY" section entirely from 'memory-barriers.txt' as it doesn't
make any sense now that the dependency barriers have been removed.
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Acked-by: Paul E. McKenney <paulmck@kernel.org>
Signed-off-by: Will Deacon <will@kernel.org>
Protecting the code in a trampoline can also require protecting a
number of instructions prior to actually entering the trampoline.
For example, these earlier instructions might be computing the address
of the trampoline. This commit therefore updates RCU's requirements to
record this for posterity.
Link: https://lore.kernel.org/lkml/20200511154824.09a18c46@gandalf.local.home/
Reported-by: Lai Jiangshan <jiangshanlai@gmail.com>
Reported-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Over the past few years, there have been several cases where timekeeping
bugs have caused RCU CPU stall warnings, particularly during hardware
bringup. This commit therefore adds such bugs to the list of things
that can result in RCU CPU stall warnings.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
Since changeset 58ad30cf91 ("docs: fix reference to core-api/namespaces.rst"),
auto-references for chapters are generated. This is a nice feature, but
has a drawback: no chapters can have the same sumber.
So, we need to add two higher hierarchy chapters on this document,
in order to avoid such duplication.
Fixes: 58ad30cf91 ("docs: fix reference to core-api/namespaces.rst")
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
- Add a SPDX header;
- Adjust document and section titles;
- Fix list markups;
- Some whitespace fixes and new line breaks;
- Mark literal blocks as such;
- Add it to RCU/index.rst.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
- Add a SPDX header;
- Adjust document title;
- Some whitespace fixes and new line breaks;
- Mark literal blocks as such;
- Add it to RCU/index.rst.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
- Add a SPDX header;
- Adjust document and section titles;
- Some whitespace fixes and new line breaks;
- Mark literal blocks as such;
- Add it to RCU/index.rst.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
- Add a SPDX header;
- Adjust document title;
- Some whitespace fixes and new line breaks;
- Mark literal blocks as such;
- Add it to RCU/index.rst.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
- Add a SPDX header;
- Adjust document title;
- Mark literal blocks as such;
- Add it to RCU/index.rst.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
- Add a SPDX header;
- Add a document title;
- Some whitespace fixes and new line breaks;
- Mark literal blocks as such;
- Add it to RCU/index.rst.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
- Add a SPDX header;
- Adjust document title;
- Some whitespace fixes and new line breaks;
- Use the right list markups;
- Add it to RCU/index.rst.
Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
The scheduler is currently required to hold rq/pi locks across the entire
RCU read-side critical section or not at all. This is inconvenient and
leaves traps for the unwary, including the author of this commit.
But now that excessively long grace periods enable scheduling-clock
interrupts for holdout nohz_full CPUs, the nohz_full rescue logic in
rcu_read_unlock_special() can be dispensed with. In other words, the
rcu_read_unlock_special() function can refrain from doing wakeups unless
such wakeups are guaranteed safe.
This commit therefore avoids unsafe wakeups, freeing the scheduler to
hold rq/pi locks across rcu_read_unlock() even if the corresponding RCU
read-side critical section might have been preempted. This commit also
updates RCU's requirements documentation.
This commit is inspired by a patch from Lai Jiangshan:
https://lore.kernel.org/lkml/20191102124559.1135-2-laijs@linux.alibaba.com
This commit is further intended to be a step towards his goal of permitting
the inlining of RCU-preempt's rcu_read_lock() and rcu_read_unlock().
Cc: Lai Jiangshan <laijs@linux.alibaba.com>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
For testing mainline, the kvm.sh rcutorture script is the preferred
approach to testing. This commit therefore adds it to the torture.txt
documentation.
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
listRCU.rst document gives an example with 'ipc_lock()', but the
function has dropped off by commit 82061c57ce ("ipc: drop
ipc_lock()"). Because the main logic of 'ipc_lock()' has melded in
'shm_lock()' by the commit, this commit updates the document to use
'shm_lock()' instead.
Reviewed-by: Madhuparna Bhowmik <madhuparnabhowmik04@gmail.com>
Signed-off-by: SeongJae Park <sjpark@amazon.de>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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>
- Add more information about RCU list patterns taking examples
from audit subsystem in the linux kernel.
- Keep the current audit examples, even though the kernel has changed.
- Modify inline text for better passage quality.
- Fix typo in code-blocks and improve code comments.
- Add text formatting (italics, bold and code) for better emphasis.
Patch originally submitted at
https://lore.kernel.org/patchwork/patch/1082804/
Co-developed-by: Amol Grover <frextrite@gmail.com>
Signed-off-by: Amol Grover <frextrite@gmail.com>
Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
Signed-off-by: Paul E. McKenney <paulmck@kernel.org>
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>
