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

…git/paulmck/linux-rcu into core/rcu

Pull RCU updates from Paul E. McKenney:

" 1.      Update RCU documentation.  These were posted to LKML at
          https://lkml.org/lkml/2014/4/28/634.

  2.      Miscellaneous fixes.  These were posted to LKML at
          https://lkml.org/lkml/2014/4/28/645.

  3.      Torture-test changes.  These were posted to LKML at
          https://lkml.org/lkml/2014/4/28/667.

  4.      Variable-name renaming cleanup, sent separately due to conflicts.
          This was posted to LKML at https://lkml.org/lkml/2014/5/13/854.

  5.      Patch to suppress RCU stall warnings while sysrq requests are
          being processed.  This patch is the RCU portions of the patch
          that Rik posted to LKML at https://lkml.org/lkml/2014/4/29/457.
          The reason for pushing this patch ahead instead of waiting until
          3.17 is that the NMI-based stack traces are messing up sysrq
          output, and in some cases also messing up the system as well."

Signed-off-by: Ingo Molnar <[email protected]>

Documentation/RCU/00-INDEX

@@ -12,6 +12,8 @@ lockdep-splat.txt
 	- RCU Lockdep splats explained.
 NMI-RCU.txt
 	- Using RCU to Protect Dynamic NMI Handlers
+rcu_dereference.txt
+	- Proper care and feeding of return values from rcu_dereference()
 rcubarrier.txt
 	- RCU and Unloadable Modules
 rculist_nulls.txt

Documentation/RCU/checklist.txt

@@ -114,12 +114,16 @@ over a rather long period of time, but improvements are always welcome!
 			http://www.openvms.compaq.com/wizard/wiz_2637.html
 
 		The rcu_dereference() primitive is also an excellent
-		documentation aid, letting the person reading the code
-		know exactly which pointers are protected by RCU.
+		documentation aid, letting the person reading the
+		code know exactly which pointers are protected by RCU.
 		Please note that compilers can also reorder code, and
 		they are becoming increasingly aggressive about doing
-		just that.  The rcu_dereference() primitive therefore
-		also prevents destructive compiler optimizations.
+		just that.  The rcu_dereference() primitive therefore also
+		prevents destructive compiler optimizations.  However,
+		with a bit of devious creativity, it is possible to
+		mishandle the return value from rcu_dereference().
+		Please see rcu_dereference.txt in this directory for
+		more information.
 
 		The rcu_dereference() primitive is used by the
 		various "_rcu()" list-traversal primitives, such