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* rcu: Remove srcu_read_lock_raw() and srcu_read_unlock_raw().Paul E. McKenney2013-06-101-15/+7
| | | | | | | | | 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>
* rcu: Make bugginess of code sample more evidentPaul E. McKenney2013-03-121-2/+2
| | | | | | | | | | 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>
*-. Merge branches 'urgent.2012.10.27a', 'doc.2012.11.16a', 'fixes.2012.11.13a', ↵Paul E. McKenney2012-11-161-5/+12
|\ \ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | '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.
| | * rcu: Remove list_for_each_continue_rcu()Paul E. McKenney2012-11-131-3/+1
| |/ |/| | | | | | | | | | | | | 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>
| * rcu: Update docs to include kfree_rcu()Kees Cook2012-11-081-2/+11
|/ | | | | | | | 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>
* rcu: Document SRCU dead-CPU capabilities, emphasize read-side limitsPaul E. McKenney2012-09-231-2/+7
| | | | | | | | | | | | | 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>
* rcu: Update documentation to cover call_srcu() and srcu_barrier().Paul E. McKenney2012-07-021-3/+3
| | | | | | | 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>
* docs: Additional LWN links to RCU APIKees Cook2011-12-111-0/+1
| | | | | | | | 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>
* rcu: Add documentation for raw SRCU read-side primitivesPaul E. McKenney2011-12-111-5/+13
| | | | | | | | 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>
* rcu: add documentation saying which RCU flavor to choosePaul E. McKenney2011-03-041-0/+31
| | | | | Reported-by: Paul Mackerras <paulus@samba.org> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
* rcu: Update docs for rcu_access_pointer and rcu_dereference_protectedPaul E. McKenney2010-04-141-0/+6
| | | | | | | | | | | | | | | | | | | | 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>
* rcu: Documentation update for CONFIG_PROVE_RCUPaul E. McKenney2010-02-251-5/+8
| | | | | | | | | | | | | | | | | | | | 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>
* rcu: 1Q2010 update for RCU documentationPaul E. McKenney2010-01-161-1/+2
| | | | | | | | | | | | | | | | | | | | | 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>
* rcu: Add synchronize_srcu_expedited() to the documentationPaul E. McKenney2009-10-261-1/+1
| | | | | | | | | | | | | | | | | | 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>
* rcu: Remove CONFIG_PREEMPT_RCUPaul E. McKenney2009-08-231-4/+4
| | | | | | | | | | | | | | | | | | | 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>
* rcu: Add synchronize_sched_expedited() rcutorture doc + updatesPaul E. McKenney2009-07-031-3/+11
| | | | | | | | | | | | | | | | | | | | | | 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>
* rcu: remove list_for_each_rcu()Paul E. McKenney2008-08-151-2/+0
| | | | | | | | 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>
* sched: 1Q08 RCU doc update, add call_rcu_sched()Paul E. McKenney2008-05-191-19/+39
| | | | | | | | | 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>
* [PATCH] srcu-3: RCU variant permitting read-side blockingPaul E. McKenney2006-10-041-0/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | 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>
* Documentation: remove duplicated wordsPaolo Ornati2006-10-031-1/+1
| | | | | | | | | | | | | | | 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>
* Fix typos in Documentation/: 'S'Matt LaPlante2006-10-031-1/+1
| | | | | | | | | | 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>
* [PATCH] RCU Documentation fixUrs Thuermann2006-07-101-2/+3
| | | | | | | | | 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>
* [PATCH] RCU documentation: self-limiting updates and call_rcu()Paul E. McKenney2006-06-251-1/+11
| | | | | | | | | | | | 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>
* [PATCH] Make RCU API inaccessible to non-GPL Linux kernel modulesPaul E. McKenney2006-06-231-1/+0
| | | | | | | | | | | 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>
* [PATCH] for_each_possible_cpu: documentaionKAMEZAWA Hiroyuki2006-03-281-1/+1
| | | | | | | | | | | | | 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>
* rcu: undeclared variable used in documentationBaruch Even2006-03-241-2/+2
| | | | | | | | | 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>
* [PATCH] RCU documentation fixes (January 2006 update)Paul E. McKenney2006-02-011-12/+17
| | | | | | | | | 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>
* [PATCH] Remove hlist_for_each_rcu() API, convert existing use to ↵Paul E. McKenney2005-11-071-2/+0
| | | | | | | | | | | | | 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>
* [PATCH] Yet another RCU documentation updatePaul E. McKenney2005-09-101-0/+902
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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