linux-toradex.git/kernel/rcupdate.c, branch v2.6.38.6

Merge branch 'rcu/urgent' of git://git.kernel.org/pub/scm/linux/kernel/git/paulmck/linux-2.6-rcu into core/rcu

2010-10-07T07:43:11+00:00

rcu: move check from rcu_dereference_bh to rcu_read_lock_bh_held

2010-10-05T21:03:02+00:00

As suggested by Linus, push the irqs_disabled() down to the
rcu_read_lock_bh_held() level so that all callers get the benefit
of the correct check.

Signed-off-by: Paul E. McKenney

rcu: define __rcu address space modifier for sparse

2010-08-20T00:17:59+00:00

This commit provides definitions for the __rcu annotation defined earlier.
This annotation permits sparse to check for correct use of RCU-protected
pointers.  If a pointer that is annotated with __rcu is accessed
directly (as opposed to via rcu_dereference(), rcu_assign_pointer(),
or one of their variants), sparse can be made to complain.  To enable
such complaints, use the new default-disabled CONFIG_SPARSE_RCU_POINTER
kernel configuration option.  Please note that these sparse complaints are
intended to be a debugging aid, -not- a code-style-enforcement mechanism.

There are special rcu_dereference_protected() and rcu_access_pointer()
accessors for use when RCU read-side protection is not required, for
example, when no other CPU has access to the data structure in question
or while the current CPU hold the update-side lock.

This patch also updates a number of docbook comments that were showing
their age.

Signed-off-by: Arnd Bergmann 
Signed-off-by: Paul E. McKenney 
Cc: Christopher Li 
Reviewed-by: Josh Triplett

tree/tiny rcu: Add debug RCU head objects

2010-06-14T23:37:26+00:00

Helps finding racy users of call_rcu(), which results in hangs because list
entries are overwritten and/or skipped.

Changelog since v4:
- Bissectability is now OK
- Now generate a WARN_ON_ONCE() for non-initialized rcu_head passed to
  call_rcu(). Statically initialized objects are detected with
  object_is_static().
- Rename rcu_head_init_on_stack to init_rcu_head_on_stack.
- Remove init_rcu_head() completely.

Changelog since v3:
- Include comments from Lai Jiangshan

This new patch version is based on the debugobjects with the newly introduced
"active state" tracker.

Non-initialized entries are all considered as "statically initialized". An
activation fixup (triggered by call_rcu()) takes care of performing the debug
object initialization without issuing any warning. Since we cannot increase the
size of struct rcu_head, I don't see much room to put an identifier for
statically initialized rcu_head structures. So for now, we have to live without
"activation without explicit init" detection. But the main purpose of this debug
option is to detect double-activations (double call_rcu() use of a rcu_head
before the callback is executed), which is correctly addressed here.

This also detects potential internal RCU callback corruption, which would cause
the callbacks to be executed twice.

Signed-off-by: Mathieu Desnoyers 
CC: David S. Miller 
CC: "Paul E. McKenney" 
CC: akpm@linux-foundation.org
CC: mingo@elte.hu
CC: laijs@cn.fujitsu.com
CC: dipankar@in.ibm.com
CC: josh@joshtriplett.org
CC: dvhltc@us.ibm.com
CC: niv@us.ibm.com
CC: tglx@linutronix.de
CC: peterz@infradead.org
CC: rostedt@goodmis.org
CC: Valdis.Kletnieks@vt.edu
CC: dhowells@redhat.com
CC: eric.dumazet@gmail.com
CC: Alexey Dobriyan 
Signed-off-by: Paul E. McKenney 
Reviewed-by: Lai Jiangshan

rcu: slim down rcutiny by removing rcu_scheduler_active and friends

2010-05-10T18:08:34+00:00

TINY_RCU does not need rcu_scheduler_active unless CONFIG_DEBUG_LOCK_ALLOC.
So conditionally compile rcu_scheduler_active in order to slim down
rcutiny a bit more.  Also gets rid of an EXPORT_SYMBOL_GPL, which is
responsible for most of the slimming.

Signed-off-by: Paul E. McKenney

rcu: create rcu_my_thread_group_empty() wrapper

2010-05-06T16:28:41+00:00

Some RCU-lockdep splat repairs need to know whether they are running
in a single-threaded process.  Unfortunately, the thread_group_empty()
primitive is defined in sched.h, and can induce #include hell.  This
commit therefore introduces a rcu_my_thread_group_empty() wrapper that
is defined in rcupdate.c, thus avoiding the need to include sched.h
everywhere.

Signed-off-by: "Paul E. McKenney"

rcu: Make RCU lockdep check the lockdep_recursion variable

2010-04-19T06:37:19+00:00

The lockdep facility temporarily disables lockdep checking by
incrementing the current->lockdep_recursion variable.  Such
disabling happens in NMIs and in other situations where lockdep
might expect to recurse on itself.

This patch therefore checks current->lockdep_recursion, disabling RCU
lockdep splats when this variable is non-zero.  In addition, this patch
removes the "likely()", as suggested by Lai Jiangshan.

Reported-by: Frederic Weisbecker 
Reported-by: David Miller 
Tested-by: Frederic Weisbecker 
Signed-off-by: Paul E. McKenney 
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: josh@joshtriplett.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
Cc: eric.dumazet@gmail.com
LKML-Reference: <20100415195039.GA22623@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar

rcu: Make rcu_read_lock_bh_held() allow for disabled BH

2010-03-16T08:57:49+00:00

Disabling BH can stand in for rcu_read_lock_bh(), and this patch
updates rcu_read_lock_bh_held() to allow for this.  In order to
avoid include-file hell, this function is moved out of line to
kernel/rcupdate.c.

This fixes a false positive RCU warning.

Reported-by: Arnd Bergmann 
Reported-by: Eric Dumazet 
Signed-off-by: Paul E. McKenney 
Acked-by: Lai Jiangshan 
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: josh@joshtriplett.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
LKML-Reference: <20100316000343.GA25857@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar

rcu: Export rcu_scheduler_active

2010-02-26T07:20:46+00:00

Kernel modules using rcu_read_lock_sched_held() must now have
access to rcu_scheduler_active, so it must be exported.

This should fix the fix for the boot-time RCU-lockdep splat.

Signed-off-by: Paul E. McKenney 
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: josh@joshtriplett.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
LKML-Reference: <20100226030230.GA7743@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar

rcu: Make rcu_read_lock_sched_held() take boot time into account

2010-02-26T07:20:46+00:00

Before the scheduler starts, all tasks are non-preemptible by
definition. So, during that time, rcu_read_lock_sched_held()
needs to always return "true".  This patch makes that be so.

Signed-off-by: Paul E. McKenney 
Cc: laijs@cn.fujitsu.com
Cc: dipankar@in.ibm.com
Cc: mathieu.desnoyers@polymtl.ca
Cc: josh@joshtriplett.org
Cc: dvhltc@us.ibm.com
Cc: niv@us.ibm.com
Cc: peterz@infradead.org
Cc: rostedt@goodmis.org
Cc: Valdis.Kletnieks@vt.edu
Cc: dhowells@redhat.com
LKML-Reference: <1267135607-7056-2-git-send-email-paulmck@linux.vnet.ibm.com>
Signed-off-by: Ingo Molnar