linux-stable.git/include/linux/rcupdate.h, branch v3.15.4

Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

2014-03-31T18:05:24+00:00

Pull RCU updates from Ingo Molnar:
 "Main changes:

   - Torture-test changes, including refactoring of rcutorture and
     introduction of a vestigial locktorture.

   - Real-time latency fixes.

   - Documentation updates.

   - Miscellaneous fixes"

* 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (77 commits)
  rcu: Provide grace-period piggybacking API
  rcu: Ensure kernel/rcu/rcu.h can be sourced/used stand-alone
  rcu: Fix sparse warning for rcu_expedited from kernel/ksysfs.c
  notifier: Substitute rcu_access_pointer() for rcu_dereference_raw()
  Documentation/memory-barriers.txt: Clarify release/acquire ordering
  rcutorture: Save kvm.sh output to log
  rcutorture: Add a lock_busted to test the test
  rcutorture: Place kvm-test-1-run.sh output into res directory
  rcutorture: Rename TREE_RCU-Kconfig.txt
  locktorture: Add kvm-recheck.sh plug-in for locktorture
  rcutorture: Gracefully handle NULL cleanup hooks
  locktorture: Add vestigial locktorture configuration
  rcutorture: Introduce "rcu" directory level underneath configs
  rcutorture: Rename kvm-test-1-rcu.sh
  rcutorture: Remove RCU dependencies from ver_functions.sh API
  rcutorture: Create CFcommon file for common Kconfig parameters
  rcutorture: Create config files for scripted test-the-test testing
  rcutorture: Add an rcu_busted to test the test
  locktorture: Add a lock-torture kernel module
  rcutorture: Abstract kvm-recheck.sh
  ...

Merge branches 'doc.2014.02.24a', 'fixes.2014.02.26a' and 'rt.2014.02.17b' into HEAD

2014-02-26T14:36:09+00:00

doc.2014.02.24a: Documentation changes
fixes.2014.02.26a: Miscellaneous fixes
rt.2014.02.17b: Response-time-related changes

rcu: Fix sparse warning for rcu_expedited from kernel/ksysfs.c

2014-02-26T14:35:16+00:00

This commit fixes the follwoing warning:

kernel/ksysfs.c:143:5: warning: symbol 'rcu_expedited' was not declared. Should it be static?

Signed-off-by: Paul Gortmaker 
[ paulmck: Moved the declaration to include/linux/rcupdate.h to avoid
	   including the RCU-internal rcu.h file outside of RCU. ]
Signed-off-by: Paul E. McKenney 
Reviewed-by: Josh Triplett

rcu: Optimize rcu_needs_cpu() for RCU_NOCB_CPU_ALL

2014-02-18T00:03:09+00:00

If CONFIG_RCU_NOCB_CPU_ALL=y, then rcu_needs_cpu() will always
return false, however, the current version nevertheless checks
for RCU callbacks.  This commit therefore creates a static inline
implementation of rcu_needs_cpu() that unconditionally returns false
when CONFIG_RCU_NOCB_CPU_ALL=y.

Signed-off-by: Paul E. McKenney 
Reviewed-by: Josh Triplett

rcu: Optimize rcu_is_nocb_cpu() for RCU_NOCB_CPU_ALL

2014-02-17T23:32:48+00:00

If CONFIG_RCU_NOCB_CPU_ALL=y, then rcu_is_nocb_cpu() will always
return true, however, the current version nevertheless checks
rcu_nocb_mask.  This commit therefore creates a static inline
implementation of rcu_is_nocb_cpu() that unconditionally returns
true when CONFIG_RCU_NOCB_CPU_ALL=y.

Signed-off-by: Paul E. McKenney 
Reviewed-by: Josh Triplett

rcu: Define rcu_assign_pointer() in terms of smp_store_release()

2014-02-17T23:02:00+00:00

The new smp_store_release() function provides better guarantees than did
rcu_assign_pointer(), and potentially less overhead on some architectures.
The guarantee that smp_store_release() provides that rcu_assign_pointer()
does that is obscure, but its lack could cause considerable confusion.
This guarantee is illustrated by the following code fragment:

	struct foo {
		int a;
		int b;
		int c;
		struct foo *next;
	};
	struct foo foo1;
	struct foo foo2;
	struct foo __rcu *foop;

	...

	foo2.a = 1;
	foo2.b = 2;
	BUG_ON(foo2.c);
	rcu_assign_pointer(foop, &foo);

	...

	fp = rcu_dereference(foop);
	fp.c = 3;

The current rcu_assign_pointer() semantics permit the BUG_ON() to
trigger because rcu_assign_pointer()'s smp_wmb() is not guaranteed to
order prior reads against later writes.  This commit therefore upgrades
rcu_assign_pointer() from smp_wmb() to smp_store_release() to avoid this
counter-intuitive outcome.

Signed-off-by: Paul E. McKenney 
Reviewed-by: Josh Triplett

rcu: Indentation and spacing fixes.

2014-02-17T23:01:52+00:00

This commit outdents expression-statement macros, thus repairing a few
line-length complaints.  Also fix some spacing errors called out by
checkpatch.pl.

Signed-off-by: Joe Perches 
Signed-off-by: Paul E. McKenney 
Reviewed-by: Josh Triplett

rcu: Glue ASCII strings together

2014-02-17T23:01:47+00:00

Split strings make it difficult to find the code that resulted in a
given console message, so this commit glues split strings back together
despite the resulting long lines.

Signed-off-by: Joe Perches 
Signed-off-by: Paul E. McKenney 
Reviewed-by: Josh Triplett

rcu: Stop tracking FSF's postal address

2014-02-17T23:01:37+00:00

All of the RCU source files have the usual GPL header, which contains a
long-obsolete postal address for FSF.  To avoid the need to track the
FSF office's movements, this commit substitutes the URL where GPL may
be found.

Reported-by: Greg KH 
Reported-by: Steven Rostedt 
Signed-off-by: Paul E. McKenney 
Reviewed-by: Josh Triplett

lockdep: Make held_lock->check and "int check" argument bool

2014-02-09T20:18:54+00:00

The "int check" argument of lock_acquire() and held_lock->check are
misleading. This is actually a boolean: 2 means "true", everything
else is "false".

And there is no need to pass 1 or 0 to lock_acquire() depending on
CONFIG_PROVE_LOCKING, __lock_acquire() checks prove_locking at the
start and clears "check" if !CONFIG_PROVE_LOCKING.

Note: probably we can simply kill this member/arg. The only explicit
user of check => 0 is rcu_lock_acquire(), perhaps we can change it to
use lock_acquire(trylock =>, read => 2). __lockdep_no_validate means
check => 0 implicitly, but we can change validate_chain() to check
hlock->instance->key instead. Not to mention it would be nice to get
rid of lockdep_set_novalidate_class().

Signed-off-by: Oleg Nesterov 
Cc: Dave Jones 
Cc: Greg Kroah-Hartman 
Cc: Linus Torvalds 
Cc: Paul McKenney 
Cc: Steven Rostedt 
Cc: Alan Stern 
Cc: Sasha Levin 
Signed-off-by: Peter Zijlstra 
Link: http://lkml.kernel.org/r/20140120182006.GA26495@redhat.com
Signed-off-by: Ingo Molnar