[PATCH] tracing/function-return-tracer: Free the return stack on free_task()

[Frederic Weisbecker]

Impact: avoid loosing some traces when a task is freed

do_exit() is not the last function called when a task finishes.
There are still some functions which are to be called such as free_task().
So we delay the freeing of the return stack to the last moment.

Signed-off-by: Frederic Weisbecker <fweisbec@xxxxxxxxx>

diff --git a/kernel/exit.c b/kernel/exit.c
index c8334ed..cb24037 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -47,7 +47,6 @@
 #include <linux/task_io_accounting_ops.h>
 #include <linux/tracehook.h>
 #include <trace/sched.h>
-#include <linux/ftrace.h>
 
 #include <asm/uaccess.h>
 #include <asm/unistd.h>
@@ -1125,7 +1124,6 @@ NORET_TYPE void do_exit(long code)
 	preempt_disable();
 	/* causes final put_task_struct in finish_task_switch(). */
 	tsk->state = TASK_DEAD;
-	ftrace_retfunc_exit_task(tsk);
 	schedule();
 	BUG();
 	/* Avoid "noreturn function does return".  */
diff --git a/kernel/fork.c b/kernel/fork.c
index 354d3f0..d183739 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -141,6 +141,7 @@ void free_task(struct task_struct *tsk)
 	prop_local_destroy_single(&tsk->dirties);
 	free_thread_info(tsk->stack);
 	rt_mutex_debug_task_free(tsk);
+	ftrace_retfunc_exit_task(tsk);
 	free_task_struct(tsk);
 }
 EXPORT_SYMBOL(free_task);
-- 
1.5.2.5

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