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path: root/Documentation/RCU/whatisRCU.txt
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2014-08-07list: fix order of arguments for hlist_add_after(_rcu)Ken Helias
All other add functions for lists have the new item as first argument and the position where it is added as second argument. This was changed for no good reason in this function and makes using it unnecessary confusing. The name was changed to hlist_add_behind() to cause unconverted code to generate a compile error instead of using the wrong parameter order. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Ken Helias <kenhelias@firemail.de> Cc: "Paul E. McKenney" <paulmck@linux.vnet.ibm.com> Acked-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com> [intel driver bits] Cc: Hugh Dickins <hughd@google.com> Cc: Christoph Hellwig <hch@infradead.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2014-04-29documentation: Update API documentationPaul E. McKenney
This commit updates the list of RCU API members in whatisRCU.txt. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2013-06-10rcu: Remove srcu_read_lock_raw() and srcu_read_unlock_raw().Paul E. McKenney
These interfaces never did get used, so this commit removes them, their rcutorture tests, and documentation referencing them. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org>
2013-03-12rcu: Make bugginess of code sample more evidentPaul E. McKenney
One of the code samples in whatisRCU.txt shows a bug, but someone scanning the document quickly might mistake it for a valid use of RCU. Add some screaming comments to help keep speed-readers on track. Reported-by: Nathan Zimmer <nzimmer@sgi.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
2012-11-16Merge branches 'urgent.2012.10.27a', 'doc.2012.11.16a', 'fixes.2012.11.13a', ↵Paul E. McKenney
'srcu.2012.10.27a', 'stall.2012.11.13a', 'tracing.2012.11.08a' and 'idle.2012.10.24a' into HEAD urgent.2012.10.27a: Fix for RCU user-mode transition (already in -tip). doc.2012.11.08a: Documentation updates, most notably codifying the memory-barrier guarantees inherent to grace periods. fixes.2012.11.13a: Miscellaneous fixes. srcu.2012.10.27a: Allow statically allocated and initialized srcu_struct structures (courtesy of Lai Jiangshan). stall.2012.11.13a: Add more diagnostic information to RCU CPU stall warnings, also decrease from 60 seconds to 21 seconds. hotplug.2012.11.08a: Minor updates to CPU hotplug handling. tracing.2012.11.08a: Improved debugfs tracing, courtesy of Michael Wang. idle.2012.10.24a: Updates to RCU idle/adaptive-idle handling, including a boot parameter that maps normal grace periods to expedited. Resolved conflict in kernel/rcutree.c due to side-by-side change.
2012-11-13rcu: Remove list_for_each_continue_rcu()Paul E. McKenney
The list_for_each_continue_rcu() macro is no longer used, so this commit removes it. The list_for_each_entry_continue_rcu() macro should be used instead. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2012-11-08rcu: Update docs to include kfree_rcu()Kees Cook
Mention kfree_rcu() in the call_rcu() section. Additionally fix the example code for list replacement that used the wrong structure element. Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2012-09-23rcu: Document SRCU dead-CPU capabilities, emphasize read-side limitsPaul E. McKenney
The current documentation did not help someone grepping for SRCU to learn that disabling preemption is not a replacement for srcu_read_lock(), so upgrade the documentation to bring this out, not just for SRCU, but also for RCU-bh. Also document the fact that SRCU readers are respected on CPUs executing in user mode, idle CPUs, and even on offline CPUs. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Reviewed-by: Josh Triplett <josh@joshtriplett.org> Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>
2012-07-02rcu: Update documentation to cover call_srcu() and srcu_barrier().Paul E. McKenney
The advent of call_srcu() and srcu_barrier() obsoleted some of the documentation, so this commit brings that up to date. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2011-12-11docs: Additional LWN links to RCU APIKees Cook
Tyler Hicks pointed me at an additional article on RCU and I figured it should probably be mentioned with the others. Signed-off-by: Kees Cook <keescook@chromium.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2011-12-11rcu: Add documentation for raw SRCU read-side primitivesPaul E. McKenney
Update various files in Documentation/RCU to reflect srcu_read_lock_raw() and srcu_read_unlock_raw(). Credit to Peter Zijlstra for suggesting use of the existing _raw suffix instead of the earlier bulkref names. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2011-03-04rcu: add documentation saying which RCU flavor to choosePaul E. McKenney
Reported-by: Paul Mackerras <paulus@samba.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
2010-04-14rcu: Update docs for rcu_access_pointer and rcu_dereference_protectedPaul E. McKenney
Update examples and lists of APIs to include these new primitives. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: laijs@cn.fujitsu.com Cc: dipankar@in.ibm.com Cc: mathieu.desnoyers@polymtl.ca Cc: josh@joshtriplett.org Cc: dvhltc@us.ibm.com Cc: niv@us.ibm.com Cc: peterz@infradead.org Cc: rostedt@goodmis.org Cc: Valdis.Kletnieks@vt.edu Cc: dhowells@redhat.com Cc: eric.dumazet@gmail.com LKML-Reference: <1270852752-25278-3-git-send-email-paulmck@linux.vnet.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2010-02-25rcu: Documentation update for CONFIG_PROVE_RCUPaul E. McKenney
Adds a lockdep.txt file and updates checklist.txt and whatisRCU.txt to reflect the new lockdep-enabled capabilities of RCU. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: laijs@cn.fujitsu.com Cc: dipankar@in.ibm.com Cc: mathieu.desnoyers@polymtl.ca Cc: josh@joshtriplett.org Cc: dvhltc@us.ibm.com Cc: niv@us.ibm.com Cc: peterz@infradead.org Cc: rostedt@goodmis.org Cc: Valdis.Kletnieks@vt.edu Cc: dhowells@redhat.com LKML-Reference: <1266887105-1528-13-git-send-email-paulmck@linux.vnet.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2010-01-16rcu: 1Q2010 update for RCU documentationPaul E. McKenney
Add expedited functions. Review documentation and update obsolete verbiage. Also fix the advice for the RCU CPU-stall kernel configuration parameter, and document RCU CPU-stall warnings. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: laijs@cn.fujitsu.com Cc: dipankar@in.ibm.com Cc: mathieu.desnoyers@polymtl.ca Cc: josh@joshtriplett.org Cc: dvhltc@us.ibm.com Cc: niv@us.ibm.com Cc: peterz@infradead.org Cc: rostedt@goodmis.org Cc: Valdis.Kletnieks@vt.edu Cc: dhowells@redhat.com LKML-Reference: <12635142581866-git-send-email-> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-10-26rcu: Add synchronize_srcu_expedited() to the documentationPaul E. McKenney
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Acked-by: Josh Triplett <josh@joshtriplett.org> Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com> Cc: dipankar@in.ibm.com Cc: mathieu.desnoyers@polymtl.ca Cc: dvhltc@us.ibm.com Cc: niv@us.ibm.com Cc: peterz@infradead.org Cc: rostedt@goodmis.org Cc: Valdis.Kletnieks@vt.edu Cc: dhowells@redhat.com Cc: avi@redhat.com Cc: mtosatti@redhat.com LKML-Reference: <12565226354176-git-send-email-> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-08-23rcu: Remove CONFIG_PREEMPT_RCUPaul E. McKenney
Now that CONFIG_TREE_PREEMPT_RCU is in place, there is no further need for CONFIG_PREEMPT_RCU. Remove it, along with whatever subtle bugs it may (or may not) contain. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: laijs@cn.fujitsu.com Cc: dipankar@in.ibm.com Cc: akpm@linux-foundation.org Cc: mathieu.desnoyers@polymtl.ca Cc: josht@linux.vnet.ibm.com Cc: dvhltc@us.ibm.com Cc: niv@us.ibm.com Cc: peterz@infradead.org Cc: rostedt@goodmis.org LKML-Reference: <125097461396-git-send-email-> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2009-07-03rcu: Add synchronize_sched_expedited() rcutorture doc + updatesPaul E. McKenney
This patch updates the rcutorture documentation to include updated output format. It also brings the RCU documentation up to date. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: akpm@linux-foundation.org Cc: torvalds@linux-foundation.org Cc: davem@davemloft.net Cc: dada1@cosmosbay.com Cc: zbr@ioremap.net Cc: jeff.chua.linux@gmail.com Cc: paulus@samba.org Cc: laijs@cn.fujitsu.com Cc: jengelh@medozas.de Cc: r000n@r000n.net Cc: benh@kernel.crashing.org Cc: mathieu.desnoyers@polymtl.ca LKML-Reference: <12459460983193-git-send-email-> Signed-off-by: Ingo Molnar <mingo@elte.hu>
2008-08-15rcu: remove list_for_each_rcu()Paul E. McKenney
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>
2008-05-19sched: 1Q08 RCU doc update, add call_rcu_sched()Paul E. McKenney
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>
2006-10-04[PATCH] srcu-3: RCU variant permitting read-side blockingPaul E. McKenney
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>
2006-10-03Documentation: remove duplicated wordsPaolo Ornati
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>
2006-10-03Fix typos in Documentation/: 'S'Matt LaPlante
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>
2006-07-10[PATCH] RCU Documentation fixUrs Thuermann
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>
2006-06-25[PATCH] RCU documentation: self-limiting updates and call_rcu()Paul E. McKenney
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>
2006-06-23[PATCH] Make RCU API inaccessible to non-GPL Linux kernel modulesPaul E. McKenney
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>
2006-03-28[PATCH] for_each_possible_cpu: documentaionKAMEZAWA Hiroyuki
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>
2006-03-24rcu: undeclared variable used in documentationBaruch Even
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>
2006-02-01[PATCH] RCU documentation fixes (January 2006 update)Paul E. McKenney
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>
2005-11-07[PATCH] Remove hlist_for_each_rcu() API, convert existing use to ↵Paul E. McKenney
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>
2005-09-10[PATCH] Yet another RCU documentation updatePaul E. McKenney
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>
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