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-rw-r--r--include/linux/ftrace.h2
-rw-r--r--kernel/sched.c2
-rw-r--r--kernel/trace/ftrace.c52
3 files changed, 48 insertions, 8 deletions
diff --git a/include/linux/ftrace.h b/include/linux/ftrace.h
index dcd6a7c3a435..ca29e03c1fac 100644
--- a/include/linux/ftrace.h
+++ b/include/linux/ftrace.h
@@ -428,6 +428,7 @@ extern void unregister_ftrace_graph(void);
extern void ftrace_graph_init_task(struct task_struct *t);
extern void ftrace_graph_exit_task(struct task_struct *t);
+extern void ftrace_graph_init_idle_task(struct task_struct *t, int cpu);
static inline int task_curr_ret_stack(struct task_struct *t)
{
@@ -451,6 +452,7 @@ static inline void unpause_graph_tracing(void)
static inline void ftrace_graph_init_task(struct task_struct *t) { }
static inline void ftrace_graph_exit_task(struct task_struct *t) { }
+static inline void ftrace_graph_init_idle_task(struct task_struct *t, int cpu) { }
static inline int register_ftrace_graph(trace_func_graph_ret_t retfunc,
trace_func_graph_ent_t entryfunc)
diff --git a/kernel/sched.c b/kernel/sched.c
index 18d38e4ec7ba..fbe86cb04b61 100644
--- a/kernel/sched.c
+++ b/kernel/sched.c
@@ -5571,7 +5571,7 @@ void __cpuinit init_idle(struct task_struct *idle, int cpu)
* The idle tasks have their own, simple scheduling class:
*/
idle->sched_class = &idle_sched_class;
- ftrace_graph_init_task(idle);
+ ftrace_graph_init_idle_task(idle, cpu);
}
/*
diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index f3dadae83883..888b611897d3 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -3328,7 +3328,7 @@ static int start_graph_tracing(void)
/* The cpu_boot init_task->ret_stack will never be freed */
for_each_online_cpu(cpu) {
if (!idle_task(cpu)->ret_stack)
- ftrace_graph_init_task(idle_task(cpu));
+ ftrace_graph_init_idle_task(idle_task(cpu), cpu);
}
do {
@@ -3418,6 +3418,49 @@ void unregister_ftrace_graph(void)
mutex_unlock(&ftrace_lock);
}
+static DEFINE_PER_CPU(struct ftrace_ret_stack *, idle_ret_stack);
+
+static void
+graph_init_task(struct task_struct *t, struct ftrace_ret_stack *ret_stack)
+{
+ atomic_set(&t->tracing_graph_pause, 0);
+ atomic_set(&t->trace_overrun, 0);
+ t->ftrace_timestamp = 0;
+ /* make curr_ret_stack visable before we add the ret_stack */
+ smp_wmb();
+ t->ret_stack = ret_stack;
+}
+
+/*
+ * Allocate a return stack for the idle task. May be the first
+ * time through, or it may be done by CPU hotplug online.
+ */
+void ftrace_graph_init_idle_task(struct task_struct *t, int cpu)
+{
+ t->curr_ret_stack = -1;
+ /*
+ * The idle task has no parent, it either has its own
+ * stack or no stack at all.
+ */
+ if (t->ret_stack)
+ WARN_ON(t->ret_stack != per_cpu(idle_ret_stack, cpu));
+
+ if (ftrace_graph_active) {
+ struct ftrace_ret_stack *ret_stack;
+
+ ret_stack = per_cpu(idle_ret_stack, cpu);
+ if (!ret_stack) {
+ ret_stack = kmalloc(FTRACE_RETFUNC_DEPTH
+ * sizeof(struct ftrace_ret_stack),
+ GFP_KERNEL);
+ if (!ret_stack)
+ return;
+ per_cpu(idle_ret_stack, cpu) = ret_stack;
+ }
+ graph_init_task(t, ret_stack);
+ }
+}
+
/* Allocate a return stack for newly created task */
void ftrace_graph_init_task(struct task_struct *t)
{
@@ -3433,12 +3476,7 @@ void ftrace_graph_init_task(struct task_struct *t)
GFP_KERNEL);
if (!ret_stack)
return;
- atomic_set(&t->tracing_graph_pause, 0);
- atomic_set(&t->trace_overrun, 0);
- t->ftrace_timestamp = 0;
- /* make curr_ret_stack visable before we add the ret_stack */
- smp_wmb();
- t->ret_stack = ret_stack;
+ graph_init_task(t, ret_stack);
}
}