linux.git/Documentation/RCU, branch v4.11

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

2017-01-25T20:56:05+00:00

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

rcu: Eliminate unused expedited_normal counter

2017-01-23T19:37:14+00:00

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 
Reviewed-by: Josh Triplett

doc: Quick-Quiz answers are now inline

2017-01-15T05:30:33+00:00

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 
Reviewed-by: Josh Triplett

doc: Fix RCU requirements typos

2017-01-15T05:29:10+00:00

Signed-off-by: Tetsuo Handa 
Signed-off-by: Paul E. McKenney 
Reviewed-by: Josh Triplett

rcu: Design documentation for expedited grace periods

2017-01-15T05:28:58+00:00

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 
Reviewed-by: Josh Triplett

Documentation/RCU: Fix minor typo

2016-11-14T18:39:48+00:00

deference should actually be dereference.

Signed-off-by: Pranith Kumar 
Reviewed-by: Josh Triplett 
Signed-off-by: Paul E. McKenney

documentation: Present updated RCU guarantee

2016-11-14T18:39:36+00:00

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

kthread: kthread worker API cleanup

2016-10-11T22:06:33+00:00

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 
Signed-off-by: Petr Mladek 
Cc: Oleg Nesterov 
Cc: Tejun Heo 
Cc: Ingo Molnar 
Cc: Peter Zijlstra 
Cc: Steven Rostedt 
Cc: "Paul E. McKenney" 
Cc: Josh Triplett 
Cc: Thomas Gleixner 
Cc: Jiri Kosina 
Cc: Borislav Petkov 
Cc: Michal Hocko 
Cc: Vlastimil Babka 
Signed-off-by: Arnd Bergmann 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

documentation: Record reason for rcu_head two-byte alignment

2016-08-22T16:25:33+00:00

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

rcutorture: Remove outdated config option description

2016-08-22T16:23:23+00:00

CONFIG_RCU_TORTURE_TEST_RUNNABLE was removed by commit 4e9a073f60367
("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 
Signed-off-by: Paul E. McKenney