Commit Graph

35 Commits

Author SHA1 Message Date
Eric Dumazet 536533e69e rcu: documents rculist_nulls
Adds Documentation/RCU/rculist_nulls.txt file to describe how 'nulls'
end-of-list can help in some RCU algos.

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: David S. Miller <davem@davemloft.net>
2008-11-16 19:41:14 -08:00
Lai Jiangshan e8aed68614 doc/RCU: fix pseudocode in rcuref.txt
atomic_inc_not_zero(v) return 0 if *v = 0.
use spin_lock instead of write_lock for update lock.

Signed-off-by: Lai Jiangshan <laijs@cn.fujitsu.com>
Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-09-10 08:36:07 +02:00
Paul E. McKenney 34d7c2b38d rcu: remove list_for_each_rcu()
All of the in-tree uses of list_for_each_rcu() have been converted to
list_for_each_entry_rcu(), so list_for_each_rcu() can now be removed.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-08-15 17:03:06 +02:00
Paul E. McKenney 0729fbf3bc rcu: make rcutorture even more vicious: invoke RCU readers from irq handlers (timers)
This patch allows torturing RCU from irq handlers (timers, in this case).
A new module parameter irqreader enables such additional torturing,
and is enabled by default.  Variants of RCU that do not tolerate readers
being called from irq handlers (e.g., SRCU) ignore irqreader.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: josh@freedesktop.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: dino@in.ibm.com
Cc: akpm@linux-foundation.org
Cc: torvalds@linux-foundation.org
Cc: vegard.nossum@gmail.com
Cc: adobriyan@gmail.com
Cc: oleg@tv-sign.ru
Cc: bunk@kernel.org
Cc: rjw@sisk.pl
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-26 09:24:33 +02:00
Paul E. McKenney 31a72bce0b rcu: make rcutorture more vicious: reinstate boot-time testing
This patch re-institutes the ability to build rcutorture directly into
the Linux kernel.  The reason that this capability was removed was that
this could result in your kernel being pretty much useless, as rcutorture
would be running starting from early boot.  This problem has been avoided
by (1) making rcutorture run only three seconds of every six by default,
(2) adding a CONFIG_RCU_TORTURE_TEST_RUNNABLE that permits rcutorture
to be quiesced at boot time, and (3) adding a sysctl in /proc named
/proc/sys/kernel/rcutorture_runnable that permits rcutorture to be
quiesced and unquiesced when built into the kernel.

Please note that this /proc file is -not- available when rcutorture
is built as a module.  Please also note that to get the earlier
take-no-prisoners behavior, you must use the boot command line to set
rcutorture's "stutter" parameter to zero.

The rcutorture quiescing mechanism is currently quite crude: loops
in each rcutorture process that poll a global variable once per tick.
Suggestions for improvement are welcome.  The default action will
be to reduce the polling rate to a few times per second.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Suggested-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-19 11:22:15 +02:00
Paul E. McKenney d120f65f3a rcu: make rcutorture more vicious: add stutter feature
This patch takes a step towards making rcutorture more brutal by allowing
the test to be automatically periodically paused, with the default being
to run the test for five seconds then pause for five seconds and repeat.
This behavior can be controlled using a new "stutter" module parameter, so
that "stutter=0" gives the old default behavior of running continuously.

Starting and stopping rcutorture more heavily stresses RCU's interaction
with the scheduler, as well as exercising more paths through the
grace-period detection code.

Note that the default to "shuffle_interval" has also been adjusted from
5 seconds to 3 seconds to provide varying overlap with the "stutter"
interval.

I am still unable to provoke the failures that Alexey has been seeing,
even with this patch, but will be doing a few additional things to beef
up rcutorture.

Suggested-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-06-18 15:06:56 +02:00
Paul E. McKenney 32300751b4 sched: 1Q08 RCU doc update, add call_rcu_sched()
Long-delayed update to the RCU documentation, including adding the new
call_rcu_sched() and rcu_barrier_sched() APIs.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
2008-05-19 10:01:37 +02:00
Harvey Harrison b5606c2d44 remove final fastcall users
fastcall always expands to empty, remove it.

Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-02-13 16:21:18 -08:00
Paul E. McKenney f85d6c7168 Preempt-RCU: update RCU Documentation.
This patch updates the RCU documentation to reflect preemptible RCU as
well as recent publications.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Signed-off-by: Gautham R Shenoy <ego@in.ibm.com>
Reviewed-by: Steven Rostedt <srostedt@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-01-25 21:08:25 +01:00
Rob Landley e54e54a94c Add Documentation/RCU/00-Index
Add Documentation/RCU/00-INDEX

Signed-off-by: Rob Landley <rob@landley.net>
Acked-by: Paul E. McKenney <paulmck@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-10-17 08:43:07 -07:00
Paul E. McKenney ef48bd2461 Document the fact that RCU callbacks can run in parallel
Add an item to the RCU documentation checklist noting that RCU callbacks
can run in parallel.

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-07-16 09:05:47 -07:00
Josh Triplett 4b6c2cca6e [PATCH] rcu: add sched torture type to rcutorture
Implement torture testing for the "sched" variant of RCU, which uses
preempt_disable, preempt_enable, and synchronize_sched.

Signed-off-by: Josh Triplett <josh@freedesktop.org>
Acked-by: Paul E. McKenney <paulmck@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-10-04 07:55:31 -07:00
Josh Triplett 11a147013e [PATCH] rcu: add rcu_bh_sync torture type to rcutorture
Use the newly-generic synchronous deferred free function to implement torture
testing for rcu_bh using synchronize_rcu_bh rather than the asynchronous
call_rcu_bh.

Signed-off-by: Josh Triplett <josh@freedesktop.org>
Acked-by: Paul E. McKenney <paulmck@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-10-04 07:55:31 -07:00
Josh Triplett 20d2e4283a [PATCH] rcu: add rcu_sync torture type to rcutorture
Use the newly-generic synchronous deferred free function to implement torture
testing for RCU using synchronize_rcu rather than the asynchronous call_rcu.

Signed-off-by: Josh Triplett <josh@freedesktop.org>
Acked-by: Paul E. McKenney <paulmck@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-10-04 07:55:31 -07:00
Josh Triplett b772e1dd4b [PATCH] RCU: add fake writers to rcutorture
rcutorture currently has one writer and an arbitrary number of readers.  To
better exercise some of the code paths in RCU implementations, add fake
writer threads which call the synchronize function for the RCU variant in a
loop, with a delay between calls to arrange for different numbers of
writers running in parallel.

[bunk@stusta.de: cleanup]
Acked-by: Paul McKenney <paulmck@us.ibm.com>
Cc: Dipkanar Sarma <dipankar@in.ibm.com>
Signed-off-by: Josh Triplett <josh@freedesktop.org>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-10-04 07:55:31 -07:00
Paul E. McKenney b2896d2e75 [PATCH] srcu-3: add SRCU operations to rcutorture
Adds SRCU operations to rcutorture and updates rcutorture documentation.
Also increases the stress imposed by the rcutorture test.

[bunk@stusta.de: make needlessly global code static]
Signed-off-by: Paul E. McKenney <paulmck@us.ibm.com>
Cc: Paul E. McKenney <paulmck@us.ibm.com>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-10-04 07:55:30 -07:00
Paul E. McKenney 621934ee7e [PATCH] srcu-3: RCU variant permitting read-side blocking
Updated patch adding a variant of RCU that permits sleeping in read-side
critical sections.  SRCU is as follows:

o	Each use of SRCU creates its own srcu_struct, and each
	srcu_struct has its own set of grace periods.  This is
	critical, as it prevents one subsystem with a blocking
	reader from holding up SRCU grace periods for other
	subsystems.

o	The SRCU primitives (srcu_read_lock(), srcu_read_unlock(),
	and synchronize_srcu()) all take a pointer to a srcu_struct.

o	The SRCU primitives must be called from process context.

o	srcu_read_lock() returns an int that must be passed to
	the matching srcu_read_unlock().  Realtime RCU avoids the
	need for this by storing the state in the task struct,
	but SRCU needs to allow a given code path to pass through
	multiple SRCU domains -- storing state in the task struct
	would therefore require either arbitrary space in the
	task struct or arbitrary limits on SRCU nesting.  So I
	kicked the state-storage problem up to the caller.

	Of course, it is not permitted to call synchronize_srcu()
	while in an SRCU read-side critical section.

o	There is no call_srcu().  It would not be hard to implement
	one, but it seems like too easy a way to OOM the system.
	(Hey, we have enough trouble with call_rcu(), which does
	-not- permit readers to sleep!!!)  So, if you want it,
	please tell me why...

[josht@us.ibm.com: sparse notation]
Signed-off-by: Paul E. McKenney <paulmck@us.ibm.com>
Signed-off-by: Josh Triplett <josh@freedesktop.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-10-04 07:55:30 -07:00
Paolo Ornati 670e9f34ee Documentation: remove duplicated words
Remove many duplicated words under Documentation/ and do other small
cleanups.

Examples:
        "and and" --> "and"
        "in in" --> "in"
        "the the" --> "the"
        "the the" --> "to the"
        ...

Signed-off-by: Paolo Ornati <ornati@fastwebnet.it>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
2006-10-03 22:57:56 +02:00
Matt LaPlante 53cb47268e Fix typos in Documentation/: 'S'
This patch fixes typos in various Documentation txts. The patch addresses
some words starting with the letter 'S'.

Signed-off-by: Matt LaPlante <kernel1@cyberdogtech.com>
Acked-by: Alan Cox <alan@redhat.com>
Acked-by: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
2006-10-03 22:55:17 +02:00
Urs Thuermann 82a854ec4f [PATCH] RCU Documentation fix
Updater should use _rcu variant of list_del().

Signed-off-by: Urs Thuermann <urs@isnogud.escape.de>
Acked-by: "Paul E. McKenney" <paulmck@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-07-10 13:24:15 -07:00
Paul E. McKenney 72e9bb5492 [PATCH] rcutorture: add ops vector and Classic RCU ops
Add an ops vector to rcutorture, and add the ops for Classic RCU.  Update
the rcutorture documentation to reflect slight change to the dmesg formats.

Signed-off-by: Paul E. McKenney <paulmck@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-27 17:32:40 -07:00
Paul E. McKenney 29766f1eb3 [PATCH] rcutorture: catchup doc fixes for idle-hz tests
This just catches the RCU torture documentation up with the recent fixes
that test RCU for architectures that turn of the scheduling-clock interrupt
for idle CPUs and the addition of a SUCCESS/FAILURE indication, fixing up
an obsolete comment as well.

Signed-off-by: Paul E. McKenney <paulmck@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-27 17:32:40 -07:00
Paul E. McKenney 165d6c78ee [PATCH] RCU documentation: self-limiting updates and call_rcu()
An update to the RCU documentation calling out the
self-limiting-update-rate advantages of synchronize_rcu(), and describing
how to use call_rcu() in a way that results in self-limiting updates.
Self-limiting updates are important to avoiding RCU-induced OOM in face of
denial-of-service attacks.

Signed-off-by: Paul E. McKenney <paulmck@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-25 10:01:17 -07:00
Paul E. McKenney d83015b8f6 [PATCH] Make RCU API inaccessible to non-GPL Linux kernel modules
Remove synchronize_kernel() (deprecated 2-APR-2005 in
http://lkml.org/lkml/2005/4/3/11) and makes the RCU API inaccessible to
non-GPL Linux kernel modules (as was announced more than one year ago in
http://lkml.org/lkml/2005/4/3/8).  Tested on x86 and ppc64.

Signed-off-by: "Paul E. McKenney" <paulmck@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-23 07:43:07 -07:00
KAMEZAWA Hiroyuki 3c30a75256 [PATCH] for_each_possible_cpu: documentaion
Replace for_each_cpu with for_each_possible_cpu.

Modifies occurences in documentaion.

for_each_cpu in whatisRCU.txt should be for_each_online_cpu ???
(I'm not sure..)

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-03-28 09:16:05 -08:00
Baruch Even de0dfcdf55 rcu: undeclared variable used in documentation
The RCU documentation uses an fp variable which is not declared in the code
snippets. Use the new_fp variable instead.

Signed-Off-By: Baruch Even <baruch@ev-en.org>
Acked-by: <paulmck@us.ibm.com>
Signed-off-by: Adrian Bunk <bunk@stusta.de>
2006-03-24 18:25:25 +01:00
Paul E. McKenney d19720a909 [PATCH] RCU documentation fixes (January 2006 update)
Updates to in-tree RCU documentation based on comments over the past few
months.

Signed-off-by: "Paul E. McKenney" <paulmck@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-02-01 08:53:25 -08:00
Nick Piggin 095975da26 [PATCH] rcu file: use atomic primitives
Use atomic_inc_not_zero for rcu files instead of special case rcuref.

Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: "Paul E. McKenney" <paulmck@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-08 20:13:48 -08:00
Paul E. McKenney 665a7583f3 [PATCH] Remove hlist_for_each_rcu() API, convert existing use to hlist_for_each_entry_rcu
Remove the hlist_for_each_rcu() API, which is used only in one place, and
is trivially converted to hlist_for_each_entry_rcu(), making the code
shorter and more readable.  Any out-of-tree uses may be similarly
converted.

Signed-off-by: "Paul E. McKenney" <paulmck@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-07 07:53:35 -08:00
Paul E. McKenney a241ec65ae [PATCH] RCU torture-testing kernel module
This patch is a rewrite of the one submitted on October 1st, using modules
(http://marc.theaimsgroup.com/?l=linux-kernel&m=112819093522998&w=2).

This rewrite adds a tristate CONFIG_RCU_TORTURE_TEST, which enables an
intense torture test of the RCU infratructure.  This is needed due to the
continued changes to the RCU infrastructure to accommodate dynamic ticks,
CPU hotplug, realtime, and so on.  Most of the code is in a separate file
that is compiled only if the CONFIG variable is set.  Documentation on how
to run the test and interpret the output is also included.

This code has been tested on i386 and ppc64, and an earlier version of the
code has received extensive testing on a number of architectures as part of
the PREEMPT_RT patchset.

Signed-off-by: "Paul E. McKenney" <paulmck@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-30 17:37:27 -08:00
Paul E. McKenney dd81eca83c [PATCH] Yet another RCU documentation update
Update RCU documentation based on discussions and review of RCU-based tree
patches.  Add an introductory whatisRCU.txt file.

Signed-off-by: <paulmck@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-10 10:06:24 -07:00
Dipankar Sarma c0dfb29051 [PATCH] files: rcuref APIs
Adds a set of primitives to do reference counting for objects that are looked
up without locks using RCU.

Signed-off-by: Ravikiran Thirumalai <kiran_th@gmail.com>
Signed-off-by: Dipankar Sarma <dipankar@in.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-09 13:57:54 -07:00
Paul E. McKenney 19306059cd [PATCH] NMI: Update NMI users of RCU to use new API
Uses of RCU for dynamically changeable NMI handlers need to use the new
rcu_dereference() and rcu_assign_pointer() facilities.  This change makes
it clear that these uses are safe from a memory-barrier viewpoint, but the
main purpose is to document exactly what operations are being protected by
RCU.  This has been tested on x86 and x86-64, which are the only
architectures affected by this change.

Signed-off-by: <paulmck@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-07 16:57:19 -07:00
Paul E. McKenney a83f1fe27f [PATCH] Update RCU documentation
Update the RCU documentation to allow for the new synchronize_rcu() and
synchronize_sched() primitives.  Fix a few other nits as well.

Signed-off-by: Paul E. McKenney <paulmck@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-05-01 08:59:05 -07:00
Linus Torvalds 1da177e4c3 Linux-2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.

Let it rip!
2005-04-16 15:20:36 -07:00