1 files changed, 40 insertions, 16 deletions

diff --git a/kernel/sched.c b/kernel/sched.c
index 5e43e9dc65d1..cbb3a0eee58e 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -2573,7 +2573,26 @@ static void ttwu_queue_remote(struct task_struct *p, int cpu)
         if (!next)
                 smp_send_reschedule(cpu);
 }
-#endif
+
+#ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
+static int ttwu_activate_remote(struct task_struct *p, int wake_flags)
+{
+        struct rq *rq;
+        int ret = 0;
+
+        rq = __task_rq_lock(p);
+        if (p->on_cpu) {
+                ttwu_activate(rq, p, ENQUEUE_WAKEUP);
+                ttwu_do_wakeup(rq, p, wake_flags);
+                ret = 1;
+        }
+        __task_rq_unlock(rq);
+
+        return ret;
+
+}
+#endif /* __ARCH_WANT_INTERRUPTS_ON_CTXSW */
+#endif /* CONFIG_SMP */
 
 static void ttwu_queue(struct task_struct *p, int cpu)
 {
@@ -2631,17 +2650,17 @@ try_to_wake_up(struct task_struct *p, unsigned int state, int wake_flags)
         while (p->on_cpu) {
 #ifdef __ARCH_WANT_INTERRUPTS_ON_CTXSW
                 /*
-                 * If called from interrupt context we could have landed in the
-                 * middle of schedule(), in this case we should take care not
-                 * to spin on ->on_cpu if p is current, since that would
-                 * deadlock.
+                 * In case the architecture enables interrupts in
+                 * context_switch(), we cannot busy wait, since that
+                 * would lead to deadlocks when an interrupt hits and
+                 * tries to wake up @prev. So bail and do a complete
+                 * remote wakeup.
                  */
-                if (p == current) {
-                        ttwu_queue(p, cpu);
+                if (ttwu_activate_remote(p, wake_flags))
                         goto stat;
-                }
-#endif
+#else
                 cpu_relax();
+#endif
         }
         /*
          * Pairs with the smp_wmb() in finish_lock_switch().
@@ -5841,7 +5860,7 @@ void __cpuinit init_idle(struct task_struct *idle, int cpu)
         idle->state = TASK_RUNNING;
         idle->se.exec_start = sched_clock();
 
-        cpumask_copy(&idle->cpus_allowed, cpumask_of(cpu));
+        do_set_cpus_allowed(idle, cpumask_of(cpu));
         /*
          * We're having a chicken and egg problem, even though we are
          * holding rq->lock, the cpu isn't yet set to this cpu so the
@@ -5929,6 +5948,16 @@ static inline void sched_init_granularity(void)
 }
 
 #ifdef CONFIG_SMP
+void do_set_cpus_allowed(struct task_struct *p, const struct cpumask *new_mask)
+{
+        if (p->sched_class && p->sched_class->set_cpus_allowed)
+                p->sched_class->set_cpus_allowed(p, new_mask);
+        else {
+                cpumask_copy(&p->cpus_allowed, new_mask);
+                p->rt.nr_cpus_allowed = cpumask_weight(new_mask);
+        }
+}
+
 /*
  * This is how migration works:
  *
@@ -5974,12 +6003,7 @@ int set_cpus_allowed_ptr(struct task_struct *p, const struct cpumask *new_mask)
                 goto out;
         }
 
-        if (p->sched_class->set_cpus_allowed)
-                p->sched_class->set_cpus_allowed(p, new_mask);
-        else {
-                cpumask_copy(&p->cpus_allowed, new_mask);
-                p->rt.nr_cpus_allowed = cpumask_weight(new_mask);
-        }
+        do_set_cpus_allowed(p, new_mask);
 
         /* Can the task run on the task's current CPU? If so, we're done */
         if (cpumask_test_cpu(task_cpu(p), new_mask))