user/sven/linux.git/kernel/rcu, branch v4.9.5

Merge tag 'gcc-plugins-v4.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

2016-10-15T17:03:15Z

Pull gcc plugins update from Kees Cook: "This adds a new gcc plugin named "latent_entropy". It is designed to extract as much possible uncertainty from a running system at boot time as possible, hoping to capitalize on any possible variation in CPU operation (due to runtime data differences, hardware differences, SMP ordering, thermal timing variation, cache behavior, etc). At the very least, this plugin is a much more comprehensive example for how to manipulate kernel code using the gcc plugin internals" * tag 'gcc-plugins-v4.9-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: latent_entropy: Mark functions with __latent_entropy gcc-plugins: Add latent_entropy plugin

latent_entropy: Mark functions with __latent_entropy

2016-10-10T21:51:45Z

The __latent_entropy gcc attribute can be used only on functions and variables. If it is on a function then the plugin will instrument it for gathering control-flow entropy. If the attribute is on a variable then the plugin will initialize it with random contents. The variable must be an integer, an integer array type or a structure with integer fields. These specific functions have been selected because they are init functions (to help gather boot-time entropy), are called at unpredictable times, or they have variable loops, each of which provide some level of latent entropy. Signed-off-by: Emese Revfy [kees: expanded commit message] Signed-off-by: Kees Cook

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

2016-10-03T19:15:00Z

Pull locking updates from Ingo Molnar: "The main changes in this cycle were: - rwsem micro-optimizations (Davidlohr Bueso) - Improve the implementation and optimize the performance of percpu-rwsems. (Peter Zijlstra.) - Convert all lglock users to better facilities such as percpu-rwsems or percpu-spinlocks and remove lglocks. (Peter Zijlstra) - Remove the ticket (spin)lock implementation. (Peter Zijlstra) - Korean translation of memory-barriers.txt and related fixes to the English document. (SeongJae Park) - misc fixes and cleanups" * 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (24 commits) x86/cmpxchg, locking/atomics: Remove superfluous definitions x86, locking/spinlocks: Remove ticket (spin)lock implementation locking/lglock: Remove lglock implementation stop_machine: Remove stop_cpus_lock and lg_double_lock/unlock() fs/locks: Use percpu_down_read_preempt_disable() locking/percpu-rwsem: Add down_read_preempt_disable() fs/locks: Replace lg_local with a per-cpu spinlock fs/locks: Replace lg_global with a percpu-rwsem locking/percpu-rwsem: Add DEFINE_STATIC_PERCPU_RWSEMand percpu_rwsem_assert_held() locking/pv-qspinlock: Use cmpxchg_release() in __pv_queued_spin_unlock() locking/rwsem, x86: Drop a bogus cc clobber futex: Add some more function commentry locking/hung_task: Show all locks locking/rwsem: Scan the wait_list for readers only once locking/rwsem: Remove a few useless comments locking/rwsem: Return void in __rwsem_mark_wake() locking, rcu, cgroup: Avoid synchronize_sched() in __cgroup_procs_write() locking/Documentation: Add Korean translation locking/Documentation: Fix a typo of example result locking/Documentation: Fix wrong section reference ...

Merge branches 'doc.2016.08.22c', 'exp.2016.08.22c', 'fixes.2016.09.14a', 'hotplug.2016.08.22c' and 'torture.2016.08.22c' into HEAD

2016-09-14T19:58:49Z

doc.2016.08.22c: Documentation updates exp.2016.08.22c: Expedited grace-period updates fixes.2016.09.14a: Miscellaneous fixes hotplug.2016.08.22c: CPU-hotplug changes torture.2016.08.22c: Torture-test changes

rcuperf: Consistently insert space between flag and message

2016-08-22T17:06:16Z

A few rcuperf dmesg output messages have no space between the flag and the start of the message. In contrast, every other messages consistently supplies a single space. This difference makes rcuperf dmesg output hard to read and to mechanically parse. This commit therefore fixes this problem by modifying a pr_alert() call and PERFOUT_STRING() macro function to provide that single space. Signed-off-by: SeongJae Park Signed-off-by: Paul E. McKenney

rcutorture: Print out barrier error as document says

2016-08-22T17:03:37Z

Tests for rcu_barrier() were introduced by commit fae4b54f28f0 ("rcu: Introduce rcutorture testing for rcu_barrier()"). This commit updated the documentation to say that the "rtbe" field in rcutorture's dmesg output indicates test failure. However, the code was not updated, only the documentation. This commit therefore updates the code to match the updated documentation. Signed-off-by: SeongJae Park Signed-off-by: Paul E. McKenney

torture: Add task state to writer-task stall printk()s

2016-08-22T17:02:59Z

This commit adds a dump of the scheduler state for stalled rcutorture writer tasks. This addition provides yet more debug for the intermittent "failures to proceed", where grace periods move ahead but the rcutorture writer tasks fail to do so. Signed-off-by: Paul E. McKenney

rcutorture: Convert to hotplug state machine

2016-08-22T16:52:12Z

Install the callbacks via the state machine and let the core invoke the callbacks on the already online CPUs. Cc: Josh Triplett Cc: "Paul E. McKenney" Cc: Steven Rostedt Cc: Mathieu Desnoyers Cc: Lai Jiangshan Signed-off-by: Sebastian Andrzej Siewior Signed-off-by: Paul E. McKenney

rcu: Provide exact CPU-online tracking for RCU

2016-08-22T16:36:57Z

Up to now, RCU has assumed that the CPU-online process makes it from CPU_UP_PREPARE to set_cpu_online() within one jiffy. Given the recent rise of virtualized environments, this assumption is very clearly obsolete. Failing to meet this deadline can result in RCU paying attention to an incoming CPU for one jiffy, then ignoring it until the grace period following the one in which that CPU sets itself online. This situation might prove to be fatally disappointing to any RCU read-side critical sections that had the misfortune to execute during the time in which RCU was ignoring the slow-to-come-online CPU. This commit therefore updates RCU's internal CPU state-tracking information at notify_cpu_starting() time, thus providing RCU with an exact transition of the CPU's state from offline to online. Note that this means that incoming CPUs must not use RCU read-side critical section (other than those of SRCU) until notify_cpu_starting() time. Note also that the CPU_STARTING notifiers -are- allowed to use RCU read-side critical sections. (Of course, CPU-hotplug notifiers are rapidly becoming obsolete, so you need to act fast!) If a given architecture or CPU family needs to use RCU read-side critical sections earlier, the call to rcu_cpu_starting() from notify_cpu_starting() will need to be architecture-specific, with architectures that need early use being required to hand-place the call to rcu_cpu_starting() at some point preceding the call to notify_cpu_starting(). Signed-off-by: Paul E. McKenney

rcu: Avoid redundant quiescent-state chasing

2016-08-22T16:35:57Z

Currently, __note_gp_changes() checks to see if the CPU has slept through multiple grace periods. If it has, it resynchronizes that CPU's view of the grace-period state, which includes whether or not the current grace period needs a quiescent state from this CPU. The fact of this need (or lack thereof) needs to be in two places, rdp->cpu_no_qs.b.norm and rdp->core_needs_qs. The former tells RCU's context-switch code to go get a quiescent state and the latter says that it needs to be reported. The current code unconditionally sets the former to true, but correctly sets the latter. This does not result in failures, but it does unnecessarily increase the amount of work done on average at context-switch time. This commit therefore correctly sets both fields. Signed-off-by: Paul E. McKenney