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authorLinus Torvalds <torvalds@linux-foundation.org>2012-12-11 18:10:49 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2012-12-11 18:10:49 -0800
commit37ea95a959d4a49846ecbf2dd45326b6b34bf049 (patch)
tree43791e1244ce06d8ca18ecbfd0b0f6dcb86ebb8b /Documentation/RCU/checklist.txt
parentde0c276b31538fcd56611132f20b63eae2891876 (diff)
parent630e1e0bcddfda9566462d4f9a0d58b31c29d467 (diff)
Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
Pull RCU update from Ingo Molnar: "The major features of this tree are: 1. A first version of no-callbacks CPUs. This version prohibits offlining CPU 0, but only when enabled via CONFIG_RCU_NOCB_CPU=y. Relaxing this constraint is in progress, but not yet ready for prime time. These commits were posted to LKML at https://lkml.org/lkml/2012/10/30/724. 2. Changes to SRCU that allows statically initialized srcu_struct structures. These commits were posted to LKML at https://lkml.org/lkml/2012/10/30/296. 3. Restructuring of RCU's debugfs output. These commits were posted to LKML at https://lkml.org/lkml/2012/10/30/341. 4. Additional CPU-hotplug/RCU improvements, posted to LKML at https://lkml.org/lkml/2012/10/30/327. Note that the commit eliminating __stop_machine() was judged to be too-high of risk, so is deferred to 3.9. 5. Changes to RCU's idle interface, most notably a new module parameter that redirects normal grace-period operations to their expedited equivalents. These were posted to LKML at https://lkml.org/lkml/2012/10/30/739. 6. Additional diagnostics for RCU's CPU stall warning facility, posted to LKML at https://lkml.org/lkml/2012/10/30/315. The most notable change reduces the default RCU CPU stall-warning time from 60 seconds to 21 seconds, so that it once again happens sooner than the softlockup timeout. 7. Documentation updates, which were posted to LKML at https://lkml.org/lkml/2012/10/30/280. A couple of late-breaking changes were posted at https://lkml.org/lkml/2012/11/16/634 and https://lkml.org/lkml/2012/11/16/547. 8. Miscellaneous fixes, which were posted to LKML at https://lkml.org/lkml/2012/10/30/309. 9. Finally, a fix for an lockdep-RCU splat was posted to LKML at https://lkml.org/lkml/2012/11/7/486." * 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (49 commits) context_tracking: New context tracking susbsystem sched: Mark RCU reader in sched_show_task() rcu: Separate accounting of callbacks from callback-free CPUs rcu: Add callback-free CPUs rcu: Add documentation for the new rcuexp debugfs trace file rcu: Update documentation for TREE_RCU debugfs tracing rcu: Reduce default RCU CPU stall warning timeout rcu: Fix TINY_RCU rcu_is_cpu_rrupt_from_idle check rcu: Clarify memory-ordering properties of grace-period primitives rcu: Add new rcutorture module parameters to start/end test messages rcu: Remove list_for_each_continue_rcu() rcu: Fix batch-limit size problem rcu: Add tracing for synchronize_sched_expedited() rcu: Remove old debugfs interfaces and also RCU flavor name rcu: split 'rcuhier' to each flavor rcu: split 'rcugp' to each flavor rcu: split 'rcuboost' to each flavor rcu: split 'rcubarrier' to each flavor rcu: Fix tracing formatting rcu: Remove the interface "rcudata.csv" ...
Diffstat (limited to 'Documentation/RCU/checklist.txt')
-rw-r--r--Documentation/RCU/checklist.txt17
1 files changed, 8 insertions, 9 deletions
diff --git a/Documentation/RCU/checklist.txt b/Documentation/RCU/checklist.txt
index cdb20d41a44a..31ef8fe07f82 100644
--- a/Documentation/RCU/checklist.txt
+++ b/Documentation/RCU/checklist.txt
@@ -271,15 +271,14 @@ over a rather long period of time, but improvements are always welcome!
The same cautions apply to call_rcu_bh() and call_rcu_sched().
9. All RCU list-traversal primitives, which include
- rcu_dereference(), list_for_each_entry_rcu(),
- list_for_each_continue_rcu(), and list_for_each_safe_rcu(),
- must be either within an RCU read-side critical section or
- must be protected by appropriate update-side locks. RCU
- read-side critical sections are delimited by rcu_read_lock()
- and rcu_read_unlock(), or by similar primitives such as
- rcu_read_lock_bh() and rcu_read_unlock_bh(), in which case
- the matching rcu_dereference() primitive must be used in order
- to keep lockdep happy, in this case, rcu_dereference_bh().
+ rcu_dereference(), list_for_each_entry_rcu(), and
+ list_for_each_safe_rcu(), must be either within an RCU read-side
+ critical section or must be protected by appropriate update-side
+ locks. RCU read-side critical sections are delimited by
+ rcu_read_lock() and rcu_read_unlock(), or by similar primitives
+ such as rcu_read_lock_bh() and rcu_read_unlock_bh(), in which
+ case the matching rcu_dereference() primitive must be used in
+ order to keep lockdep happy, in this case, rcu_dereference_bh().
The reason that it is permissible to use RCU list-traversal
primitives when the update-side lock is held is that doing so