Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 81adbdc0 authored by Steven Rostedt's avatar Steven Rostedt Committed by Ingo Molnar
Browse files

ftrace: only have ftrace_kill atomic 



When an anomaly is detected, we need a way to completely disable
ftrace. Right now we have two functions: ftrace_kill and ftrace_kill_atomic.
The ftrace_kill tries to do it in a "nice" way by converting everything
back to a nop.

The "nice" way is dangerous itself, so this patch removes it and only
has the "atomic" version, which is all that is needed.

Signed-off-by: default avatarSteven Rostedt <srostedt@redhat.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent ab9a0918

include/linux/ftrace.h

+1 −2
Original line number Diff line number Diff line
@@ -40,7 +40,7 @@ extern void ftrace_stub(unsigned long a0, unsigned long a1); 
# define register_ftrace_function(ops) do { } while (0)

# define unregister_ftrace_function(ops) do { } while (0)

# define clear_ftrace_function(ops) do { } while (0)

static inline void ftrace_kill_atomic(void) { }

static inline void ftrace_kill(void) { }

#endif /* CONFIG_FUNCTION_TRACER */



#ifdef CONFIG_DYNAMIC_FTRACE
@@ -117,7 +117,6 @@ static inline void ftrace_release(void *start, unsigned long size) { } 


/* totally disable ftrace - can not re-enable after this */

void ftrace_kill(void);

void ftrace_kill_atomic(void);



static inline void tracer_disable(void)

{

kernel/trace/ftrace.c

+2 −40
Original line number Diff line number Diff line
@@ -1549,22 +1549,6 @@ int ftrace_force_update(void) 
	return ret;

}



static void ftrace_force_shutdown(void)

{

	struct task_struct *task;

	int command = FTRACE_DISABLE_CALLS | FTRACE_UPDATE_TRACE_FUNC;



	mutex_lock(&ftraced_lock);

	task = ftraced_task;

	ftraced_task = NULL;

	ftraced_suspend = -1;

	ftrace_run_update_code(command);

	mutex_unlock(&ftraced_lock);



	if (task)

		kthread_stop(task);

}



static __init int ftrace_init_debugfs(void)

{

	struct dentry *d_tracer;
@@ -1795,17 +1779,16 @@ core_initcall(ftrace_dynamic_init); 
# define ftrace_shutdown()		do { } while (0)

# define ftrace_startup_sysctl()	do { } while (0)

# define ftrace_shutdown_sysctl()	do { } while (0)

# define ftrace_force_shutdown()	do { } while (0)

#endif /* CONFIG_DYNAMIC_FTRACE */



/**

 * ftrace_kill_atomic - kill ftrace from critical sections

 * ftrace_kill - kill ftrace

 *

 * This function should be used by panic code. It stops ftrace

 * but in a not so nice way. If you need to simply kill ftrace

 * from a non-atomic section, use ftrace_kill.

 */

void ftrace_kill_atomic(void)

void ftrace_kill(void)

{

	ftrace_disabled = 1;

	ftrace_enabled = 0;
@@ -1815,27 +1798,6 @@ void ftrace_kill_atomic(void) 
	clear_ftrace_function();

}



/**

 * ftrace_kill - totally shutdown ftrace

 *

 * This is a safety measure. If something was detected that seems

 * wrong, calling this function will keep ftrace from doing

 * any more modifications, and updates.

 * used when something went wrong.

 */

void ftrace_kill(void)

{

	mutex_lock(&ftrace_sysctl_lock);

	ftrace_disabled = 1;

	ftrace_enabled = 0;



	clear_ftrace_function();

	mutex_unlock(&ftrace_sysctl_lock);



	/* Try to totally disable ftrace */

	ftrace_force_shutdown();

}



/**

 * register_ftrace_function - register a function for profiling

 * @ops - ops structure that holds the function for profiling.

kernel/trace/trace.c

+1 −1
Original line number Diff line number Diff line
@@ -3097,7 +3097,7 @@ void ftrace_dump(void) 
	dump_ran = 1;



	/* No turning back! */

	ftrace_kill_atomic();

	ftrace_kill();



	for_each_tracing_cpu(cpu) {

		atomic_inc(&global_trace.data[cpu]->disabled);