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: Steven Rostedt
---
include/linux/ftrace.h | 3 +--
kernel/trace/ftrace.c | 42 ++----------------------------------------
kernel/trace/trace.c | 2 +-
3 files changed, 4 insertions(+), 43 deletions(-)

Index: linux-compile.git/include/linux/ftrace.h
================================================== =================
--- linux-compile.git.orig/include/linux/ftrace.h 2008-10-22 15:57:31.000000000 -0400
+++ linux-compile.git/include/linux/ftrace.h 2008-10-22 15:58:35.000000000 -0400
@@ -40,7 +40,7 @@ extern void ftrace_stub(unsigned long a0
# 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_FTRACE */

#ifdef CONFIG_DYNAMIC_FTRACE
@@ -117,7 +117,6 @@ static inline void ftrace_release(void *

/* totally disable ftrace - can not re-enable after this */
void ftrace_kill(void);
-void ftrace_kill_atomic(void);

static inline void tracer_disable(void)
{
Index: linux-compile.git/kernel/trace/ftrace.c
================================================== =================
--- linux-compile.git.orig/kernel/trace/ftrace.c 2008-10-22 15:49:49.000000000 -0400
+++ linux-compile.git/kernel/trace/ftrace.c 2008-10-22 15:58:35.000000000 -0400
@@ -1544,22 +1544,6 @@ 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;
@@ -1752,17 +1736,16 @@ 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;
@@ -1773,27 +1756,6 @@ void ftrace_kill_atomic(void)
}

/**
- * 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.
*
Index: linux-compile.git/kernel/trace/trace.c
================================================== =================
--- linux-compile.git.orig/kernel/trace/trace.c 2008-10-22 15:09:04.000000000 -0400
+++ linux-compile.git/kernel/trace/trace.c 2008-10-22 15:58:35.000000000 -0400
@@ -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);

--
--
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