Commit Graph

208 Commits

Author SHA1 Message Date
Paul E. McKenney
0f9be8cabb rcu: Eliminate flavor scan in rcu_momentary_dyntick_idle()
The rcu_momentary_dyntick_idle() function scans the RCU flavors, checking
that one of them still needs a quiescent state before doing an expensive
atomic operation on the ->dynticks counter.  However, this check reduces
overhead only after a rare race condition, and increases complexity.  This
commit therefore removes the scan and the mechanism enabling the scan.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2017-04-18 11:38:18 -07:00
Paul E. McKenney
9577df9a31 rcu: Pull rcu_qs_ctr into rcu_dynticks structure
The rcu_qs_ctr variable is yet another isolated per-CPU variable,
so this commit pulls it into the pre-existing rcu_dynticks per-CPU
structure.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2017-04-18 11:38:17 -07:00
Paul E. McKenney
abb06b9948 rcu: Pull rcu_sched_qs_mask into rcu_dynticks structure
The rcu_sched_qs_mask variable is yet another isolated per-CPU variable,
so this commit pulls it into the pre-existing rcu_dynticks per-CPU
structure.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2017-04-18 11:38:17 -07:00
Paul E. McKenney
31945aa9f1 Merge branches 'doc.2017.01.15b', 'dyntick.2017.01.23a', 'fixes.2017.01.23a', 'srcu.2017.01.25a' and 'torture.2017.01.15b' into HEAD
doc.2017.01.15b: Documentation updates
dyntick.2017.01.23a: Dyntick tracking consolidation
fixes.2017.01.23a: Miscellaneous fixes
srcu.2017.01.25a: SRCU rewrite, fixes, and verification
torture.2017.01.15b: Torture-test updates
2017-01-25 12:56:05 -08:00
Paul E. McKenney
bb4e2c08bb rcu: Eliminate unused expedited_normal counter
Expedited grace periods no longer fall back to normal grace periods
in response to lock contention, given that expedited grace periods
now use the rcu_node tree so as to avoid contention.  This commit
therfore removes the expedited_normal counter.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2017-01-23 11:37:14 -08:00
Paul E. McKenney
4afac159c3 doc: Quick-Quiz answers are now inline
Now that quick-quiz answers are inline, there is no separate section
containing those answers.  This commit therefore removes the dangling
reference from the RCU data-structures design documentation.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2017-01-14 21:30:33 -08:00
Tetsuo Handa
526914a0ae doc: Fix RCU requirements typos
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2017-01-14 21:29:10 -08:00
Paul E. McKenney
e73c14ebc3 rcu: Design documentation for expedited grace periods
This commit adds design documentation for expedited grace periods.
This documentation is in HTML rather than the new documentation
format because (1) I have prototype documentation already in HTML,
and (2) Attempting to learn the new documentation format while
creating the design documentation seems likely to result in neither
happening in a timely fashion.

Once the design documentation is complete, we can start a conversion effort.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2017-01-14 21:28:58 -08:00
Pranith Kumar
8cf503d337 Documentation/RCU: Fix minor typo
deference should actually be dereference.

Signed-off-by: Pranith Kumar <bobby.prani@gmail.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2016-11-14 10:39:48 -08:00
Paul E. McKenney
e2c85cb12c documentation: Present updated RCU guarantee
Recent memory-model work deduces the relationships of RCU read-side
critical sections and grace periods based on the relationships of
accesses within a critical section and accesses preceding and following
the grace period.  This commit therefore adds this viewpoint.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2016-11-14 10:39:36 -08:00
Petr Mladek
3989144f86 kthread: kthread worker API cleanup
A good practice is to prefix the names of functions by the name
of the subsystem.

The kthread worker API is a mix of classic kthreads and workqueues.  Each
worker has a dedicated kthread.  It runs a generic function that process
queued works.  It is implemented as part of the kthread subsystem.

This patch renames the existing kthread worker API to use
the corresponding name from the workqueues API prefixed by
kthread_:

__init_kthread_worker()		-> __kthread_init_worker()
init_kthread_worker()		-> kthread_init_worker()
init_kthread_work()		-> kthread_init_work()
insert_kthread_work()		-> kthread_insert_work()
queue_kthread_work()		-> kthread_queue_work()
flush_kthread_work()		-> kthread_flush_work()
flush_kthread_worker()		-> kthread_flush_worker()

Note that the names of DEFINE_KTHREAD_WORK*() macros stay
as they are. It is common that the "DEFINE_" prefix has
precedence over the subsystem names.

Note that INIT() macros and init() functions use different
naming scheme. There is no good solution. There are several
reasons for this solution:

  + "init" in the function names stands for the verb "initialize"
    aka "initialize worker". While "INIT" in the macro names
    stands for the noun "INITIALIZER" aka "worker initializer".

  + INIT() macros are used only in DEFINE() macros

  + init() functions are used close to the other kthread()
    functions. It looks much better if all the functions
    use the same scheme.

  + There will be also kthread_destroy_worker() that will
    be used close to kthread_cancel_work(). It is related
    to the init() function. Again it looks better if all
    functions use the same naming scheme.

  + there are several precedents for such init() function
    names, e.g. amd_iommu_init_device(), free_area_init_node(),
    jump_label_init_type(),  regmap_init_mmio_clk(),

  + It is not an argument but it was inconsistent even before.

[arnd@arndb.de: fix linux-next merge conflict]
 Link: http://lkml.kernel.org/r/20160908135724.1311726-1-arnd@arndb.de
Link: http://lkml.kernel.org/r/1470754545-17632-3-git-send-email-pmladek@suse.com
Suggested-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Petr Mladek <pmladek@suse.com>
Cc: Oleg Nesterov <oleg@redhat.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Cc: Josh Triplett <josh@joshtriplett.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Jiri Kosina <jkosina@suse.cz>
Cc: Borislav Petkov <bp@suse.de>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Vlastimil Babka <vbabka@suse.cz>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2016-10-11 15:06:33 -07:00
Paul E. McKenney
ed2bec07fd documentation: Record reason for rcu_head two-byte alignment
There is an assertion in __call_rcu() that checks only the bottom
bit of the rcu_head pointer, rather than the bottom two (as might be
expected for 32-bit systems) or the bottom three (as might be expected
for 64-bit systems).  This choice might be a bit surprising in these days
of ubiquitous 32-bit and 64-bit systems.  This commit therefore records
the reason for this odd alignment check, namely that m68k guarantees
only two-byte alignment despite being a 32-bit architectures.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2016-08-22 09:25:33 -07:00
SeongJae Park
e1ef69217f rcutorture: Remove outdated config option description
CONFIG_RCU_TORTURE_TEST_RUNNABLE was removed by commit 4e9a073f60
("torture: Remove CONFIG_RCU_TORTURE_TEST_RUNNABLE, simplify code"),
but the documentation was not updated accordingly.  This commit therefore
updates the documentation to reflect CONFIG_RCU_TORTURE_TEST_RUNNABLE's
removal and to add a description for the alternative module parameter.

Signed-off-by: SeongJae Park <sj38.park@gmail.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2016-08-22 09:23:23 -07:00
Eric Engestrom
14ef05754f Documentation: Fix spelling mistake
Signed-off-by: Eric Engestrom <eric@engestrom.ch>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2016-06-14 16:01:00 -07:00
Paul E. McKenney
c79dac758d documentation: Add RCU_NONIDLE() restrictions to requirements
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2016-06-14 16:00:59 -07:00
Paul E. McKenney
db4855b5a8 documentation: Add references to 2010 and 2014 Big API Tables
Reported-by: Jim Roskind <jar@roskind.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2016-06-14 16:00:58 -07:00
Paul E. McKenney
2921b12362 documentation: Add reference to 2014 RCU API LWN article
Reported-by: Jim Roskind <jar@roskind.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2016-06-14 16:00:58 -07:00
Linus Torvalds
e9ad9b9bd3 The most interesting thing (IMO) this time around is some beginning
infrastructural work to allow documents to be written using restructured
 text.  Maybe someday, in a galaxy far far away, we'll be able to eliminate
 the DocBook dependency and have a much better integrated set of kernel
 docs.  Someday.
 
 Beyond that, there's a new document on security hardening from Kees, the
 movement of some sample code over to samples/, a number of improvements to
 the serial docs from Geert, and the usual collection of corrections, typo
 fixes, etc.
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Merge tag 'docs-for-linus' of git://git.lwn.net/linux

Pull Documentation updates from Jon Corbet:
 "A bit busier this time around.

  The most interesting thing (IMO) this time around is some beginning
  infrastructural work to allow documents to be written using
  restructured text.  Maybe someday, in a galaxy far far away, we'll be
  able to eliminate the DocBook dependency and have a much better
  integrated set of kernel docs.  Someday.

  Beyond that, there's a new document on security hardening from Kees,
  the movement of some sample code over to samples/, a number of
  improvements to the serial docs from Geert, and the usual collection
  of corrections, typo fixes, etc"

* tag 'docs-for-linus' of git://git.lwn.net/linux: (55 commits)
  doc: self-protection: provide initial details
  serial: doc: Use port->state instead of info
  serial: doc: Always refer to tty_port->mutex
  Documentation: vm: Spelling s/paltform/platform/g
  Documentation/memcg: update kmem limit doc as codes behavior
  docproc: print a comment about autogeneration for rst output
  docproc: add support for reStructuredText format via --rst option
  docproc: abstract terminating lines at first space
  docproc: abstract docproc directive detection
  docproc: reduce unnecessary indentation
  docproc: add variables for subcommand and filename
  kernel-doc: use rst C domain directives and references for types
  kernel-doc: produce RestructuredText output
  kernel-doc: rewrite usage description, remove duplicated comments
  Doc: correct the location of sysrq.c
  Documentation: fix common spelling mistakes
  samples: v4l: from Documentation to samples directory
  samples: connector: from Documentation to samples directory
  Documentation: xillybus: fix spelling mistake
  Documentation: x86: fix spelling mistakes
  ...
2016-05-19 18:07:25 -07:00
Kees Cook
08559657b2 Documentation: fix common spelling mistakes
This fixes several spelling mistakes in the Documentation/ tree, which
are caught by checkpatch.pl's spell checking.

Signed-off-by: Kees Cook <keescook@chromium.org>
Reviewed-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
2016-04-28 07:51:59 -06:00
Paul E. McKenney
dcd36d01fb Merge branches 'doc.2016.04.19a', 'exp.2016.03.31d', 'fixes.2016.03.31d' and 'torture.2016.04.21a' into HEAD
doc.2016.04.19a: Documentation updates
exp.2016.03.31d: Expedited grace-period updates
fixes.2016.03.31d: Miscellaneous fixes
torture.2016.004.21a Torture-test updates
2016-04-21 13:48:20 -07:00
Paul E. McKenney
5c1458478c documentation: Add documentation for RCU's major data structures
This commit adds documentation for RCU's major data structures,
including rcu_state, rcu_node, rcu_data, rcu_dynticks, and rcu_head.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2016-04-19 14:48:12 -07:00
Paul E. McKenney
e2fd9d3584 rcu: Remove expedited GP funnel-lock bypass
Commit #cdacbe1f91264 ("rcu: Add fastpath bypassing funnel locking")
turns out to be a pessimization at high load because it forces a tree
full of tasks to wait for an expedited grace period that they probably
do not need.  This commit therefore removes this optimization.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2016-03-31 13:34:07 -07:00
Paul E. McKenney
0c7d10e4b9 documentation: Emphasize the call_rcu() is illegal from idle
Although call_rcu()'s fastpath works just fine on an idle CPU,
some branches of the slowpath invoke the scheduler, which uses
RCU.  Therefore, this commit emphasizes the fact that call_rcu()
must not be invoked from an idle CPU.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2016-03-31 13:33:23 -07:00
Paul E. McKenney
5413e24c94 documentation: Sharpen up the no-readers quick quiz
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2016-03-31 13:33:23 -07:00
Paul E. McKenney
6146f8df48 documentation: Get rid of duplicate .htmlx file
This commit uses colors to obscure the quick-quiz answers, thus getting
rid of the .htmlx file.  Use your mouse to select the answer in order
to see the text.  Alternatively, use your favorite scripting language
to remove all occurences of "<font color="ffffff">" from the file.

Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2016-03-31 13:33:22 -07:00
Paul E. McKenney
11a65df573 documentation: Remove unnecessary images from requirements
This commit removes a cutesy cartoon and also a diagram that can
just as easily be represented by text.

Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2016-03-31 13:33:21 -07:00
Paul E. McKenney
514f1eb5f4 documentation: Document illegality of call_rcu() from offline CPUs
There is already a blanket statement about no member of RCU's API
being legal from an offline CPU, but add an explicit note where it
states that it is illegal to invoke call_rcu() from an NMI handler.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2016-03-31 13:33:21 -07:00
Paul E. McKenney
d8936c0b7e documentation: Explain why rcu_read_lock() needs no barrier()
This commit adds a Quick Quiz whose answer explains why the compiler
code reordering enabled by CONFIG_PREEMPT=n's empty rcu_read_lock()
and rcu_read_unlock() functions does not hinder RCU's ability to figure
out which RCU read-side critical sections have completed and not.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2016-03-31 13:33:20 -07:00
Paul E. McKenney
f43b62542e documentation: Add synchronize_rcu_mult() to the requirements
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2016-03-31 13:33:20 -07:00
Paul E. McKenney
41abcf321d documentation: Add real-time requirements from CPU-bound workloads
This commit records RCU's responsibility to avoid degrading latencies
of CPUs running tight loops within properly configured workloads,
both in kernel and in userspace.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2016-03-31 13:33:19 -07:00
Yao Dongdong
70946a44de documentation: Make sample code and documentation consistent
In the chapter 'analogy with reader-writer locking', the sample
code uses spinlock_t in reader-writer case. Just correct it so
that we can read the document easily.

Signed-off-by: Yao Dongdong <yaodongdong@huawei.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2016-03-31 13:33:19 -07:00
Paul E. McKenney
c64c4b0f9a documentation: Update RCU requirements based on expedited changes
Because RCU-sched expedited grace periods now use IPIs and interact
with rcu_read_unlock(), it is no longer sufficient to disable preemption
across RCU read-side critical sections that acquire and hold scheduler
locks.  It is now necessary to instead disable interrupts.  This commit
documents this change.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2015-12-05 12:34:32 -08:00
Paul E. McKenney
4b689330b1 documentation: Clarify RCU memory barriers and requirements
The RCU requirements do not make it absolutely clear that the
memory-barrier requirements are not intended to replace the fundamental
requirement that all pre-existing RCU readers complete before a grace
period completes.  This commit therefore pulls the memory-barrier
requirements into a separate section and explicitly calls out the
relationship between the memory-barrier requirements and the fundamental
requirement.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2015-12-05 12:33:37 -08:00
Paul E. McKenney
a4b575627e documentation: Expand on scheduler/RCU deadlock requirements
This commit adds a second option for avoiding scheduler/RCU deadlocks,
namely that preemption be disabled across the entire RCU read-side
critical section in question.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2015-12-05 12:33:26 -08:00
Paul E. McKenney
0825458b1d documentation: Composability analogies
This commit expands on RCU's composability by comparing it to that of
transactional memory and of locking.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2015-12-05 12:33:11 -08:00
Paul E. McKenney
01d3ad3834 documentation: Cover requirements controlling stall warnings
This commit adds verbiage on boot and sysfs parameters that can be
used to control RCU CPU stall warnings, both to change the timeout
and to suppress these warnings entirely.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2015-12-05 12:32:19 -08:00
Paul E. McKenney
701e80312f Documentation: Record bottom-bit-zero guarantee for ->next
This commit records RCU's guarantee that the bottom bit of the rcu_head
structure's ->next field will remain zero for callbacks posted via
call_rcu(), but not necessarily for <tt>kfree_rcu()</tt> or some
possible future call_rcu_lazy() variant that might one day be created
for energy-efficiency purposese.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
[ paulmck: Updates URLs as suggested by Josh Triplett. ]
2015-12-05 12:31:47 -08:00
Paul E. McKenney
649e4368ff documentation: Record RCU requirements
This commit adds RCU requirements as published in a 2015 LWN series.
Bringing these requirements in-tree allows them to be updated as changes
are discovered.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
[ paulmck: Updates to charset and URLs as suggested by Josh Triplett. ]
2015-12-05 12:19:07 -08:00
Paul E. McKenney
39cd2dd39a Merge branches 'doc.2015.10.06a', 'percpu-rwsem.2015.10.06a' and 'torture.2015.10.06a' into HEAD
doc.2015.10.06a:  Documentation updates.
percpu-rwsem.2015.10.06a:  Optimization of per-CPU reader-writer semaphores.
torture.2015.10.06a:  Torture-test updates.
2015-10-07 16:06:25 -07:00
Paul E. McKenney
b672adf8cf documentation: Catch up list of torture_type options
This commit rids the documentation of long-obsolete torture_type options
such as rcu_sync and adds new ones such as tasks.  Also add verbiage
noting the fact that rcutorture now concurrently tests the asynchrounous,
synchronous, expedited synchronous, and polling grace-period primitives.

Reported-by: David Miller <davem@davemloft.net>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Acked-by: David Miller <davem@davemloft.net>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2015-10-06 11:22:48 -07:00
Jason A. Donenfeld
2c4ac34bc2 documentation: Correct doc to use rcu_dereference_protected
As there is lots of misinformation and outdated information on the
Internet about nearly all topics related to the kernel, I thought it
would be best if I based my RCU code on the guidelines of the examples
in the Documentation/ tree of the latest kernel. One thing that stuck
out when reading the whatisRCU.txt document was, "interesting how we
don't need any function to dereference rcu protected pointers when doing
updates if a lock is held. I wonder how static analyzers will work with
that." Then, a few weeks later, upon discovering sparse's __rcu support,
I ran it over my code, and lo and behold, things weren't done right.
Examining other RCU usages in the kernel reveal consistent usage of
rcu_dereference_protected, passing in lockdep_is_held as the
conditional. So, this patch adds that idiom to the documentation, so
that others ahead of me won't endure the same exercise.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2015-10-06 11:22:43 -07:00
Paul E. McKenney
da873def8d documentation: Call out slow consoles as cause of stall warnings
The Linux kernel outputs copious text during boot, and a slow serial
console can result in stall warnings, particularly when messages are
printed with interrupts disabled.  This commit adds this to the list
of causes of RCU CPU stall warning messages.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2015-10-06 11:22:38 -07:00
Paul E. McKenney
0d43eb34f9 rcu: Invert passed_quiesce and rename to cpu_no_qs
This commit inverts the sense of the rcu_data structure's ->passed_quiesce
field and renames it to ->cpu_no_qs.  This will allow a later commit to
use an "aggregate OR" operation to test expedited as well as normal grace
periods without added overhead.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2015-09-20 21:16:21 -07:00
Paul E. McKenney
3dbe43f6fb Merge branches 'doc.2015.07.15a' and 'torture.2015.07.15a' into HEAD
doc.2015.07.15a: Documentation updates.
torture.2015.07.15a: Torture-test updates.
2015-08-04 08:42:02 -07:00
Paul E. McKenney
8ff4fbfd69 Merge branches 'fixes.2015.07.22a' and 'initexp.2015.08.04a' into HEAD
fixes.2015.07.22a: Miscellaneous fixes.
initexp.2015.08.04a: Initialization and expedited updates.
	(Single branch due to conflicts.)
2015-08-04 08:40:58 -07:00
Paul E. McKenney
f78f5b90c4 rcu: Rename rcu_lockdep_assert() to RCU_LOCKDEP_WARN()
This commit renames rcu_lockdep_assert() to RCU_LOCKDEP_WARN() for
consistency with the WARN() series of macros.  This also requires
inverting the sense of the conditional, which this commit also does.

Reported-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Ingo Molnar <mingo@kernel.org>
2015-07-22 15:27:32 -07:00
Paul E. McKenney
cdacbe1f91 rcu: Add fastpath bypassing funnel locking
In the common case, there will be only one expedited grace period in
the system at a given time, in which case it is not helpful to use
funnel locking.  This commit therefore adds a fastpath that bypasses
funnel locking when the root ->exp_funnel_mutex is not held.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2015-07-17 14:59:06 -07:00
Paul E. McKenney
99a930b0d2 documentation: Describe new expedited stall warnings
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2015-07-17 14:59:03 -07:00
Paul E. McKenney
75c27f119b rcu: Remove CONFIG_RCU_CPU_STALL_INFO
The CONFIG_RCU_CPU_STALL_INFO has been default-y for a couple of
releases with no complaints, so it is time to eliminate this Kconfig
option entirely, so that the long-form RCU CPU stall warnings cannot
be disabled.  This commit does just that.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2015-07-17 14:58:44 -07:00
Paul E. McKenney
297f739938 documentation: Fix spelling of "operators"
Reported-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2015-07-15 14:43:10 -07:00