linux/kernel/rcu, branch v3.15

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

2014-03-31T18:21:19Z

Pull scheduler changes from Ingo Molnar: "Bigger changes: - sched/idle restructuring: they are WIP preparation for deeper integration between the scheduler and idle state selection, by Nicolas Pitre. - add NUMA scheduling pseudo-interleaving, by Rik van Riel. - optimize cgroup context switches, by Peter Zijlstra. - RT scheduling enhancements, by Thomas Gleixner. The rest is smaller changes, non-urgnt fixes and cleanups" * 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (68 commits) sched: Clean up the task_hot() function sched: Remove double calculation in fix_small_imbalance() sched: Fix broken setscheduler() sparc64, sched: Remove unused sparc64_multi_core sched: Remove unused mc_capable() and smt_capable() sched/numa: Move task_numa_free() to __put_task_struct() sched/fair: Fix endless loop in idle_balance() sched/core: Fix endless loop in pick_next_task() sched/fair: Push down check for high priority class task into idle_balance() sched/rt: Fix picking RT and DL tasks from empty queue trace: Replace hardcoding of 19 with MAX_NICE sched: Guarantee task priority in pick_next_task() sched/idle: Remove stale old file sched: Put rq's sched_avg under CONFIG_FAIR_GROUP_SCHED cpuidle/arm64: Remove redundant cpuidle_idle_call() cpuidle/powernv: Remove redundant cpuidle_idle_call() sched, nohz: Exclude isolated cores from load balancing sched: Fix select_task_rq_fair() description comments workqueue: Replace hardcoding of -20 and 19 with MIN_NICE and MAX_NICE sys: Replace hardcoding of -20 and 19 with MIN_NICE and MAX_NICE ...

rcu: Provide grace-period piggybacking API

2014-03-21T00:12:25Z

The following pattern is currently not well supported by RCU: 1. Make data element inaccessible to RCU readers. 2. Do work that probably lasts for more than one grace period. 3. Do something to make sure RCU readers in flight before #1 above have completed. Here are some things that could currently be done: a. Do a synchronize_rcu() unconditionally at either #1 or #3 above. This works, but imposes needless work and latency. b. Post an RCU callback at #1 above that does a wakeup, then wait for the wakeup at #3. This works well, but likely results in an extra unneeded grace period. Open-coding this is also a bit more semi-tricky code than would be good. This commit therefore adds get_state_synchronize_rcu() and cond_synchronize_rcu() APIs. Call get_state_synchronize_rcu() at #1 above and pass its return value to cond_synchronize_rcu() at #3 above. This results in a call to synchronize_rcu() if no grace period has elapsed between #1 and #3, but requires only a load, comparison, and memory barrier if a full grace period did elapse. Requested-by: Peter Zijlstra Signed-off-by: Paul E. McKenney Acked-by: Peter Zijlstra

Merge branch 'torture.2014.02.23a' into HEAD

2014-02-26T14:38:59Z

torture.2014.02.23a: locktorture addition and rcutorture changes

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

2014-02-26T14:36:09Z

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

rcu: Ensure kernel/rcu/rcu.h can be sourced/used stand-alone

2014-02-26T14:35:18Z

The kbuild test bot uncovered an implicit dependence on the trace header being present before rcu.h in ia64 allmodconfig that looks like this: In file included from kernel/ksysfs.c:22:0: kernel/rcu/rcu.h: In function '__rcu_reclaim': kernel/rcu/rcu.h:107:3: error: implicit declaration of function 'trace_rcu_invoke_kfree_callback' [-Werror=implicit-function-declaration] kernel/rcu/rcu.h:112:3: error: implicit declaration of function 'trace_rcu_invoke_callback' [-Werror=implicit-function-declaration] cc1: some warnings being treated as errors Looking at other rcu.h users, we can find that they all were sourcing the trace header in advance of rcu.h itself, as seen in the context of this diff. There were also some inconsistencies as to whether it was or wasn't sourced based on the parent tracing Kconfig. Rather than "fix" it at each use site, and have inconsistent use based on whether "#ifdef CONFIG_RCU_TRACE" was used or not, lets just source the trace header just once, in the actual consumer of it, which is rcu.h itself. We include it unconditionally, as build testing shows us that is a hard requirement for some files. Reported-by: kbuild test robot Signed-off-by: Paul Gortmaker Signed-off-by: Paul E. McKenney

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

2014-02-26T14:35:16Z

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

rcutorture: Add an rcu_busted to test the test

2014-02-23T17:04:30Z

This commit adds a deliberately buggy RCU implementation into rcutorture to allow easy checking that rcutorture correctly flags buggy RCU implementations. Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett

rcutorture: Stop generic kthreads in torture_cleanup()

2014-02-23T17:04:27Z

The specific torture modules (like rcutorture) need to call torture_cleanup() in any case, so this commit makes torture_cleanup() deal with torture_shutdown_cleanup() and torture_stutter_cleanup() so that the specific modules don't have to deal with these details. Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett

rcutorture: Abstract torture_stop_kthread()

2014-02-23T17:04:25Z

Stopping of kthreads is not RCU-specific, so this commit abstracts out torture_stop_kthread(), saving a few lines of code in the process. Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett

rcutorture: Abstract torture_create_kthread()

2014-02-23T17:03:24Z

Creation of kthreads is not RCU-specific, so this commit abstracts out torture_create_kthread(), saving a few tens of lines of code in the process. This change requires modifying VERBOSE_TOROUT_ERRSTRING() to take a non-const string, so that _torture_create_kthread() can avoid an open-coded substitute. Signed-off-by: Paul E. McKenney Reviewed-by: Josh Triplett