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* [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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