Merge branch 'rcu/next' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-rcu.git

Author: sfrothwell

Documentation/RCU/Design/Expedited-Grace-Periods/Expedited-Grace-Periods.rst

@@ -181,7 +181,7 @@ operations is carried out at several levels:
    of this wait (or series of waits, as the case may be) is to permit a
    concurrent CPU-hotplug operation to complete.
 #. In the case of RCU-sched, one of the last acts of an outgoing CPU is
-   to invoke ``rcu_report_dead()``, which reports a quiescent state for
+   to invoke ``rcutree_report_cpu_dead()``, which reports a quiescent state for
    that CPU. However, this is likely paranoia-induced redundancy.
 
 +-----------------------------------------------------------------------+

Documentation/RCU/Design/Memory-Ordering/TreeRCU-callback-registry.svg

@@ -1955,12 +1955,12 @@ if offline CPUs block an RCU grace period for too long.
 
 An offline CPU's quiescent state will be reported either:
 
-1.  As the CPU goes offline using RCU's hotplug notifier (rcu_report_dead()).
+1.  As the CPU goes offline using RCU's hotplug notifier (rcutree_report_cpu_dead()).
 2.  When grace period initialization (rcu_gp_init()) detects a
     race either with CPU offlining or with a task unblocking on a leaf
     ``rcu_node`` structure whose CPUs are all offline.
 
-The CPU-online path (rcu_cpu_starting()) should never need to report
+The CPU-online path (rcutree_report_cpu_starting()) should never need to report
 a quiescent state for an offline CPU.  However, as a debugging measure,
 it does emit a warning if a quiescent state was not already reported
 for that CPU.

Documentation/RCU/Design/Memory-Ordering/TreeRCU-gp-fqs.svg

@@ -241,15 +241,22 @@ over a rather long period of time, but improvements are always welcome!
 	srcu_struct.  The rules for the expedited RCU grace-period-wait
 	primitives are the same as for their non-expedited counterparts.
 
-	If the updater uses call_rcu_tasks() or synchronize_rcu_tasks(),
-	then the readers must refrain from executing voluntary
-	context switches, that is, from blocking.  If the updater uses
-	call_rcu_tasks_trace() or synchronize_rcu_tasks_trace(), then
-	the corresponding readers must use rcu_read_lock_trace() and
-	rcu_read_unlock_trace().  If an updater uses call_rcu_tasks_rude()
-	or synchronize_rcu_tasks_rude(), then the corresponding readers
-	must use anything that disables preemption, for example,
-	preempt_disable() and preempt_enable().
+	Similarly, it is necssary to correctly use the RCU Tasks flavors:
+
+	a.	If the updater uses synchronize_rcu_tasks() or
+		call_rcu_tasks(), then the readers must refrain from
+		executing voluntary context switches, that is, from
+		blocking.
+
+	b.	If the updater uses call_rcu_tasks_trace()
+		or synchronize_rcu_tasks_trace(), then the
+		corresponding readers must use rcu_read_lock_trace()
+		and rcu_read_unlock_trace().
+
+	c.	If an updater uses call_rcu_tasks_rude() or
+		synchronize_rcu_tasks_rude(), then the corresponding
+		readers must use anything that disables preemption,
+		for example, preempt_disable() and preempt_enable().
 
 	Mixing things up will result in confusion and broken kernels, and
 	has even resulted in an exploitable security issue.  Therefore,

Documentation/RCU/Design/Memory-Ordering/TreeRCU-gp.svg

@@ -8,6 +8,15 @@ One of the most common uses of RCU is protecting read-mostly linked lists
 that all of the required memory ordering is provided by the list macros.
 This document describes several list-based RCU use cases.
 
+When iterating a list while holding the rcu_read_lock(), writers may
+modify the list.  The reader is guaranteed to see all of the elements
+which were added to the list before they acquired the rcu_read_lock()
+and are still on the list when they drop the rcu_read_unlock().
+Elements which are added to, or removed from the list may or may not
+be seen.  If the writer calls list_replace_rcu(), the reader may see
+either the old element or the new element; they will not see both,
+nor will they see neither.
+
 
 Example 1: Read-mostly list: Deferred Destruction
 -------------------------------------------------

Documentation/RCU/Design/Memory-Ordering/TreeRCU-hotplug.svg

@@ -185,7 +185,7 @@ argument.
 Not all changes require that all scenarios be run.  For example, a change
 to Tree SRCU might run only the SRCU-N and SRCU-P scenarios using the
 --configs argument to kvm.sh as follows:  "--configs 'SRCU-N SRCU-P'".
-Large systems can run multiple copies of of the full set of scenarios,
+Large systems can run multiple copies of the full set of scenarios,
 for example, a system with 448 hardware threads can run five instances
 of the full set concurrently.  To make this happen::
 

Documentation/RCU/Design/Requirements/Requirements.rst

@@ -59,8 +59,8 @@ experiment with should focus on Section 2.  People who prefer to start
 with example uses should focus on Sections 3 and 4.  People who need to
 understand the RCU implementation should focus on Section 5, then dive
 into the kernel source code.  People who reason best by analogy should
-focus on Section 6.  Section 7 serves as an index to the docbook API
-documentation, and Section 8 is the traditional answer key.
+focus on Section 6 and 7.  Section 8 serves as an index to the docbook
+API documentation, and Section 9 is the traditional answer key.
 
 So, start with the section that makes the most sense to you and your
 preferred method of learning.  If you need to know everything about