linux.git/kernel/rcutree.c, branch v3.10-rc5

Merge commit '8700c95adb03' into timers/nohz

2013-05-02T15:54:19+00:00

The full dynticks tree needs the latest RCU and sched
upstream updates in order to fix some dependencies.

Merge a common upstream merge point that has these
updates.

Conflicts:
	include/linux/perf_event.h
	kernel/rcutree.h
	kernel/rcutree_plugin.h

Signed-off-by: Frederic Weisbecker

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

2013-04-30T14:39:01+00:00

Pull RCU updates from Ingo Molnar:
 "The main changes in this cycle are mostly related to preparatory work
  for the full-dynticks work:

   - Remove restrictions on no-CBs CPUs, make RCU_FAST_NO_HZ take
     advantage of numbered callbacks, do callback accelerations based on
     numbered callbacks.  Posted to LKML at
        https://lkml.org/lkml/2013/3/18/960

   - RCU documentation updates.  Posted to LKML at
        https://lkml.org/lkml/2013/3/18/570

   - Miscellaneous fixes.  Posted to LKML at
        https://lkml.org/lkml/2013/3/18/594"

* 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (24 commits)
  rcu: Make rcu_accelerate_cbs() note need for future grace periods
  rcu: Abstract rcu_start_future_gp() from rcu_nocb_wait_gp()
  rcu: Rename n_nocb_gp_requests to need_future_gp
  rcu: Push lock release to rcu_start_gp()'s callers
  rcu: Repurpose no-CBs event tracing to future-GP events
  rcu: Rearrange locking in rcu_start_gp()
  rcu: Make RCU_FAST_NO_HZ take advantage of numbered callbacks
  rcu: Accelerate RCU callbacks at grace-period end
  rcu: Export RCU_FAST_NO_HZ parameters to sysfs
  rcu: Distinguish "rcuo" kthreads by RCU flavor
  rcu: Add event tracing for no-CBs CPUs' grace periods
  rcu: Add event tracing for no-CBs CPUs' callback registration
  rcu: Introduce proper blocking to no-CBs kthreads GP waits
  rcu: Provide compile-time control for no-CBs CPUs
  rcu: Tone down debugging during boot-up and shutdown.
  rcu: Add softirq-stall indications to stall-warning messages
  rcu: Documentation update
  rcu: Make bugginess of code sample more evident
  rcu: Fix hlist_bl_set_first_rcu() annotation
  rcu: Delete unused rcu_node "wakemask" field
  ...

kernel/: rename random32() to prandom_u32()

2013-04-30T01:28:42+00:00

Use preferable function name which implies using a pseudo-random
number generator.

Signed-off-by: Akinobu Mita 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

nohz: Ensure full dynticks CPUs are RCU nocbs

2013-04-19T11:54:04+00:00

We need full dynticks CPU to also be RCU nocb so
that we don't have to keep the tick to handle RCU
callbacks.

Make sure the range passed to nohz_full= boot
parameter is a subset of rcu_nocbs=

The CPUs that fail to meet this requirement will be
excluded from the nohz_full range. This is checked
early in boot time, before any CPU has the opportunity
to stop its tick.

Suggested-by: Steven Rostedt 
Reviewed-by: Paul E. McKenney 
Signed-off-by: Frederic Weisbecker 
Cc: Andrew Morton 
Cc: Chris Metcalf 
Cc: Christoph Lameter 
Cc: Geoff Levand 
Cc: Gilad Ben Yossef 
Cc: Hakan Akkan 
Cc: Ingo Molnar 
Cc: Kevin Hilman 
Cc: Li Zhong 
Cc: Paul E. McKenney 
Cc: Paul Gortmaker 
Cc: Peter Zijlstra 
Cc: Steven Rostedt 
Cc: Thomas Gleixner

rcu: Kick adaptive-ticks CPUs that are holding up RCU grace periods

2013-04-15T18:18:36+00:00

Adaptive-ticks CPUs inform RCU when they enter kernel mode, but they do
not necessarily turn the scheduler-clock tick back on.  This state of
affairs could result in RCU waiting on an adaptive-ticks CPU running
for an extended period in kernel mode.  Such a CPU will never run the
RCU state machine, and could therefore indefinitely extend the RCU state
machine, sooner or later resulting in an OOM condition.

This patch, inspired by an earlier patch by Frederic Weisbecker, therefore
causes RCU's force-quiescent-state processing to check for this condition
and to send an IPI to CPUs that remain in that state for too long.
"Too long" currently means about three jiffies by default, which is
quite some time for a CPU to remain in the kernel without blocking.
The rcu_tree.jiffies_till_first_fqs and rcutree.jiffies_till_next_fqs
sysfs variables may be used to tune "too long" if needed.

Reported-by: Frederic Weisbecker 
Signed-off-by: Paul E. McKenney 
Reviewed-by: Josh Triplett 
Signed-off-by: Frederic Weisbecker 
Cc: Chris Metcalf 
Cc: Christoph Lameter 
Cc: Geoff Levand 
Cc: Gilad Ben Yossef 
Cc: Hakan Akkan 
Cc: Ingo Molnar 
Cc: Kevin Hilman 
Cc: Li Zhong 
Cc: Paul E. McKenney 
Cc: Paul Gortmaker 
Cc: Peter Zijlstra 
Cc: Steven Rostedt 
Cc: Thomas Gleixner

Merge branches 'doc.2013.03.12a', 'fixes.2013.03.13a' and 'idlenocb.2013.03.26b' into HEAD

2013-03-26T15:07:38+00:00

doc.2013.03.12a: Documentation changes.

fixes.2013.03.13a: Miscellaneous fixes.

idlenocb.2013.03.26b: Remove restrictions on no-CBs CPUs, make
	RCU_FAST_NO_HZ take advantage of numbered callbacks, add
	callback acceleration based on numbered callbacks.

rcu: Make rcu_accelerate_cbs() note need for future grace periods

2013-03-26T15:04:58+00:00

Now that rcu_start_future_gp() has been abstracted from
rcu_nocb_wait_gp(), rcu_accelerate_cbs() can invoke rcu_start_future_gp()
so as to register the need for any future grace periods needed by a
CPU about to enter dyntick-idle mode.  This commit makes this change.
Note that some refactoring of rcu_start_gp() is carried out to avoid
recursion and subsequent self-deadlocks.

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

rcu: Abstract rcu_start_future_gp() from rcu_nocb_wait_gp()

2013-03-26T15:04:57+00:00

CPUs going idle will need to record the need for a future grace
period, but won't actually need to block waiting on it.  This commit
therefore splits rcu_start_future_gp(), which does the recording, from
rcu_nocb_wait_gp(), which now invokes rcu_start_future_gp() to do the
recording, after which rcu_nocb_wait_gp() does the waiting.

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

rcu: Push lock release to rcu_start_gp()'s callers

2013-03-26T15:04:55+00:00

If CPUs are to give prior notice of needed grace periods, it will be
necessary to invoke rcu_start_gp() without dropping the root rcu_node
structure's ->lock.  This commit takes a second step in this direction
by moving the release of this lock to rcu_start_gp()'s callers.

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

rcu: Rearrange locking in rcu_start_gp()

2013-03-26T15:04:52+00:00

If CPUs are to give prior notice of needed grace periods, it will be
necessary to invoke rcu_start_gp() without dropping the root rcu_node
structure's ->lock.  This commit takes a first step in this direction
by moving the release of this lock to the end of rcu_start_gp().

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