Merge 'Linux v3.0' into Litmus

Some notes:
* Litmus^RT scheduling class is the topmost scheduling class
  (above stop_sched_class).
* scheduler_ipi() function (e.g., in smp_reschedule_interrupt())
  may increase IPI latencies.
* Added path into schedule() to quickly re-evaluate scheduling
  decision without becoming preemptive again. This used to be
  a standard path before the removal of BKL.

Conflicts:
	Makefile
	arch/arm/kernel/calls.S
	arch/arm/kernel/smp.c
	arch/x86/include/asm/unistd_32.h
	arch/x86/kernel/smp.c
	arch/x86/kernel/syscall_table_32.S
	include/linux/hrtimer.h
	kernel/printk.c
	kernel/sched.c
	kernel/sched_fair.c

1 files changed, 30 insertions, 9 deletions

diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c
index 48b2761b5668..c7218d132738 100644
--- a/kernel/time/tick-broadcast.c
+++ b/kernel/time/tick-broadcast.c
@@ -18,7 +18,6 @@
 #include <linux/percpu.h>
 #include <linux/profile.h>
 #include <linux/sched.h>
-#include <linux/tick.h>
 
 #include "tick-internal.h"
 
@@ -457,23 +456,27 @@ void tick_broadcast_oneshot_control(unsigned long reason)
         unsigned long flags;
         int cpu;
 
-        raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
-
         /*
          * Periodic mode does not care about the enter/exit of power
          * states
          */
         if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
-                goto out;
+                return;
 
-        bc = tick_broadcast_device.evtdev;
+        /*
+         * We are called with preemtion disabled from the depth of the
+         * idle code, so we can't be moved away.
+         */
         cpu = smp_processor_id();
         td = &per_cpu(tick_cpu_device, cpu);
         dev = td->evtdev;
 
         if (!(dev->features & CLOCK_EVT_FEAT_C3STOP))
-                goto out;
+                return;
+
+        bc = tick_broadcast_device.evtdev;
 
+        raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
         if (reason == CLOCK_EVT_NOTIFY_BROADCAST_ENTER) {
                 if (!cpumask_test_cpu(cpu, tick_get_broadcast_oneshot_mask())) {
                         cpumask_set_cpu(cpu, tick_get_broadcast_oneshot_mask());
@@ -490,8 +493,6 @@ void tick_broadcast_oneshot_control(unsigned long reason)
                                 tick_program_event(dev->next_event, 1);
                 }
         }
-
-out:
         raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags);
 }
 
@@ -523,10 +524,11 @@ static void tick_broadcast_init_next_event(struct cpumask *mask,
  */
 void tick_broadcast_setup_oneshot(struct clock_event_device *bc)
 {
+        int cpu = smp_processor_id();
+
         /* Set it up only once ! */
         if (bc->event_handler != tick_handle_oneshot_broadcast) {
                 int was_periodic = bc->mode == CLOCK_EVT_MODE_PERIODIC;
-                int cpu = smp_processor_id();
 
                 bc->event_handler = tick_handle_oneshot_broadcast;
                 clockevents_set_mode(bc, CLOCK_EVT_MODE_ONESHOT);
@@ -552,6 +554,15 @@ void tick_broadcast_setup_oneshot(struct clock_event_device *bc)
                         tick_broadcast_set_event(tick_next_period, 1);
                 } else
                         bc->next_event.tv64 = KTIME_MAX;
+        } else {
+                /*
+                 * The first cpu which switches to oneshot mode sets
+                 * the bit for all other cpus which are in the general
+                 * (periodic) broadcast mask. So the bit is set and
+                 * would prevent the first broadcast enter after this
+                 * to program the bc device.
+                 */
+                tick_broadcast_clear_oneshot(cpu);
         }
 }
 
@@ -600,4 +611,14 @@ int tick_broadcast_oneshot_active(void)
         return tick_broadcast_device.mode == TICKDEV_MODE_ONESHOT;
 }
 
+/*
+ * Check whether the broadcast device supports oneshot.
+ */
+bool tick_broadcast_oneshot_available(void)
+{
+        struct clock_event_device *bc = tick_broadcast_device.evtdev;
+
+        return bc ? bc->features & CLOCK_EVT_FEAT_ONESHOT : false;
+}
+
 #endif