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ftrace: force recording

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Signed-off-by: Ingo Molnar <mingo@elte.hu>
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
This commit is contained in:
Steven Rostedt 2008-05-12 21:20:44 +02:00 committed by Thomas Gleixner
parent 57f50be14d
commit e1c08bdd9f
2 changed files with 55 additions and 0 deletions
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4
include/linux/ftrace.h
View file

@ -54,6 +54,8 @@ struct dyn_ftrace {
unsigned long flags;
};
int ftrace_force_update(void);
/* defined in arch */
extern int ftrace_ip_converted(unsigned long ip);
extern unsigned char *ftrace_nop_replace(void);
@ -66,6 +68,8 @@ extern int ftrace_update_ftrace_func(ftrace_func_t func);
extern void ftrace_caller(void);
extern void ftrace_call(void);
extern void mcount_call(void);
#else
# define ftrace_force_update() do { } while (0)
#endif
static inline void tracer_disable(void)

51
kernel/trace/ftrace.c
View file

@ -146,6 +146,10 @@ static int notrace __unregister_ftrace_function(struct ftrace_ops *ops)
#ifdef CONFIG_DYNAMIC_FTRACE
static struct task_struct *ftraced_task;
static DECLARE_WAIT_QUEUE_HEAD(ftraced_waiters);
static unsigned long ftraced_iteration_counter;
enum {
FTRACE_ENABLE_CALLS = (1 << 0),
FTRACE_DISABLE_CALLS = (1 << 1),
@ -590,9 +594,12 @@ static int notrace ftraced(void *ignore)
ftraced_trigger = 0;
ftrace_record_suspend--;
}
ftraced_iteration_counter++;
mutex_unlock(&ftraced_lock);
mutex_unlock(&ftrace_sysctl_lock);
wake_up_interruptible(&ftraced_waiters);
ftrace_shutdown_replenish();
set_current_state(TASK_INTERRUPTIBLE);
@ -1050,6 +1057,49 @@ static struct file_operations ftrace_filter_fops = {
.release = ftrace_filter_release,
};
/**
* ftrace_force_update - force an update to all recording ftrace functions
*
* The ftrace dynamic update daemon only wakes up once a second.
* There may be cases where an update needs to be done immediately
* for tests or internal kernel tracing to begin. This function
* wakes the daemon to do an update and will not return until the
* update is complete.
*/
int ftrace_force_update(void)
{
unsigned long last_counter;
DECLARE_WAITQUEUE(wait, current);
int ret = 0;
if (!ftraced_task)
return -ENODEV;
mutex_lock(&ftraced_lock);
last_counter = ftraced_iteration_counter;
set_current_state(TASK_INTERRUPTIBLE);
add_wait_queue(&ftraced_waiters, &wait);
do {
mutex_unlock(&ftraced_lock);
wake_up_process(ftraced_task);
schedule();
mutex_lock(&ftraced_lock);
if (signal_pending(current)) {
ret = -EINTR;
break;
}
set_current_state(TASK_INTERRUPTIBLE);
} while (last_counter == ftraced_iteration_counter);
mutex_unlock(&ftraced_lock);
remove_wait_queue(&ftraced_waiters, &wait);
set_current_state(TASK_RUNNING);
return ret;
}
static __init int ftrace_init_debugfs(void)
{
struct dentry *d_tracer;
@ -1095,6 +1145,7 @@ static int __init notrace ftrace_dynamic_init(void)
return -1;
last_ftrace_enabled = ftrace_enabled = 1;
ftraced_task = p;
return 0;
}