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authorIngo Molnar <mingo@elte.hu>2009-03-04 17:49:19 (GMT)
committerIngo Molnar <mingo@elte.hu>2009-03-04 17:49:19 (GMT)
commit28b1bd1cbc33cae95a309691d814399a69cf3070 (patch)
tree6474d10332662f5302be0df8527c9e9e31e32a95 /kernel/sched.c
parent2602c3ba4508f528db024c1d209256513ea05de6 (diff)
parent1075414b06109a99b0e87601e84c74a95bd45681 (diff)
downloadlinux-fsl-qoriq-28b1bd1cbc33cae95a309691d814399a69cf3070.tar.xz
Merge branch 'core/locking' into tracing/ftrace
Diffstat (limited to 'kernel/sched.c')
-rw-r--r--kernel/sched.c71
1 files changed, 68 insertions, 3 deletions
diff --git a/kernel/sched.c b/kernel/sched.c
index 328f9c7..e1f676e 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -4543,15 +4543,13 @@ pick_next_task(struct rq *rq, struct task_struct *prev)
/*
* schedule() is the main scheduler function.
*/
-asmlinkage void __sched schedule(void)
+asmlinkage void __sched __schedule(void)
{
struct task_struct *prev, *next;
unsigned long *switch_count;
struct rq *rq;
int cpu;
-need_resched:
- preempt_disable();
cpu = smp_processor_id();
rq = cpu_rq(cpu);
rcu_qsctr_inc(cpu);
@@ -4608,13 +4606,80 @@ need_resched_nonpreemptible:
if (unlikely(reacquire_kernel_lock(current) < 0))
goto need_resched_nonpreemptible;
+}
+asmlinkage void __sched schedule(void)
+{
+need_resched:
+ preempt_disable();
+ __schedule();
preempt_enable_no_resched();
if (unlikely(test_thread_flag(TIF_NEED_RESCHED)))
goto need_resched;
}
EXPORT_SYMBOL(schedule);
+#ifdef CONFIG_SMP
+/*
+ * Look out! "owner" is an entirely speculative pointer
+ * access and not reliable.
+ */
+int mutex_spin_on_owner(struct mutex *lock, struct thread_info *owner)
+{
+ unsigned int cpu;
+ struct rq *rq;
+
+ if (!sched_feat(OWNER_SPIN))
+ return 0;
+
+#ifdef CONFIG_DEBUG_PAGEALLOC
+ /*
+ * Need to access the cpu field knowing that
+ * DEBUG_PAGEALLOC could have unmapped it if
+ * the mutex owner just released it and exited.
+ */
+ if (probe_kernel_address(&owner->cpu, cpu))
+ goto out;
+#else
+ cpu = owner->cpu;
+#endif
+
+ /*
+ * Even if the access succeeded (likely case),
+ * the cpu field may no longer be valid.
+ */
+ if (cpu >= nr_cpumask_bits)
+ goto out;
+
+ /*
+ * We need to validate that we can do a
+ * get_cpu() and that we have the percpu area.
+ */
+ if (!cpu_online(cpu))
+ goto out;
+
+ rq = cpu_rq(cpu);
+
+ for (;;) {
+ /*
+ * Owner changed, break to re-assess state.
+ */
+ if (lock->owner != owner)
+ break;
+
+ /*
+ * Is that owner really running on that cpu?
+ */
+ if (task_thread_info(rq->curr) != owner || need_resched())
+ return 0;
+
+ cpu_relax();
+ }
+out:
+ return 1;
+}
+#endif
+
#ifdef CONFIG_PREEMPT
/*
* this is the entry point to schedule() from in-kernel preemption