Commit 756d17ee authored by jolsa@redhat.com's avatar jolsa@redhat.com Committed by Ingo Molnar
Browse files

tracing: Support multiple pids in set_pid_ftrace file 



Adding the possibility to set more than 1 pid in the set_pid_ftrace
file, thus allowing to trace more than 1 independent processes.

Usage:

 sh-4.0# echo 284 > ./set_ftrace_pid
 sh-4.0# cat ./set_ftrace_pid
 284
 sh-4.0# echo 1 >> ./set_ftrace_pid
 sh-4.0# echo 0 >> ./set_ftrace_pid
 sh-4.0# cat ./set_ftrace_pid
 swapper tasks
 1
 284
 sh-4.0# echo 4 > ./set_ftrace_pid
 sh-4.0# cat ./set_ftrace_pid
 4
 sh-4.0# echo > ./set_ftrace_pid
 sh-4.0# cat ./set_ftrace_pid
 no pid
 sh-4.0#

Signed-off-by: default avatarJiri Olsa <jolsa@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <20091013203425.565454612@goodmis.org>
Signed-off-by: default avatarSteven Rostedt <rostedt@goodmis.org>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 194ec341

kernel/trace/ftrace.c

+165 −69
Original line number Diff line number Diff line
@@ -60,6 +60,13 @@ static int last_ftrace_enabled; 
/* Quick disabling of function tracer. */

int function_trace_stop;



/* List for set_ftrace_pid's pids. */

LIST_HEAD(ftrace_pids);

struct ftrace_pid {

	struct list_head list;

	struct pid *pid;

};



/*

 * ftrace_disabled is set when an anomaly is discovered.

 * ftrace_disabled is much stronger than ftrace_enabled.
@@ -159,7 +166,7 @@ static int __register_ftrace_function(struct ftrace_ops *ops) 
		else

			func = ftrace_list_func;



		if (ftrace_pid_trace) {

		if (!list_empty(&ftrace_pids)) {

			set_ftrace_pid_function(func);

			func = ftrace_pid_func;

		}
@@ -207,7 +214,7 @@ static int __unregister_ftrace_function(struct ftrace_ops *ops) 
		if (ftrace_list->next == &ftrace_list_end) {

			ftrace_func_t func = ftrace_list->func;



			if (ftrace_pid_trace) {

			if (!list_empty(&ftrace_pids)) {

				set_ftrace_pid_function(func);

				func = ftrace_pid_func;

			}
@@ -235,7 +242,7 @@ static void ftrace_update_pid_func(void) 
	func = __ftrace_trace_function;

#endif



	if (ftrace_pid_trace) {

	if (!list_empty(&ftrace_pids)) {

		set_ftrace_pid_function(func);

		func = ftrace_pid_func;

	} else {
@@ -825,8 +832,6 @@ static __init void ftrace_profile_debugfs(struct dentry *d_tracer) 
}

#endif /* CONFIG_FUNCTION_PROFILER */



/* set when tracing only a pid */

struct pid *ftrace_pid_trace;

static struct pid * const ftrace_swapper_pid = &init_struct_pid;



#ifdef CONFIG_DYNAMIC_FTRACE
@@ -2758,23 +2763,6 @@ static inline void ftrace_startup_enable(int command) { } 
# define ftrace_shutdown_sysctl()	do { } while (0)

#endif /* CONFIG_DYNAMIC_FTRACE */



static ssize_t

ftrace_pid_read(struct file *file, char __user *ubuf,

		       size_t cnt, loff_t *ppos)

{

	char buf[64];

	int r;



	if (ftrace_pid_trace == ftrace_swapper_pid)

		r = sprintf(buf, "swapper tasks\n");

	else if (ftrace_pid_trace)

		r = sprintf(buf, "%u\n", pid_vnr(ftrace_pid_trace));

	else

		r = sprintf(buf, "no pid\n");



	return simple_read_from_buffer(ubuf, cnt, ppos, buf, r);

}



static void clear_ftrace_swapper(void)

{

	struct task_struct *p;
@@ -2825,14 +2813,12 @@ static void set_ftrace_pid(struct pid *pid) 
	rcu_read_unlock();

}



static void clear_ftrace_pid_task(struct pid **pid)

static void clear_ftrace_pid_task(struct pid *pid)

{

	if (*pid == ftrace_swapper_pid)

	if (pid == ftrace_swapper_pid)

		clear_ftrace_swapper();

	else

		clear_ftrace_pid(*pid);



	*pid = NULL;

		clear_ftrace_pid(pid);

}



static void set_ftrace_pid_task(struct pid *pid)
@@ -2843,11 +2829,140 @@ static void set_ftrace_pid_task(struct pid *pid) 
		set_ftrace_pid(pid);

}



static int ftrace_pid_add(int p)

{

	struct pid *pid;

	struct ftrace_pid *fpid;

	int ret = -EINVAL;



	mutex_lock(&ftrace_lock);



	if (!p)

		pid = ftrace_swapper_pid;

	else

		pid = find_get_pid(p);



	if (!pid)

		goto out;



	ret = 0;



	list_for_each_entry(fpid, &ftrace_pids, list)

		if (fpid->pid == pid)

			goto out_put;



	ret = -ENOMEM;



	fpid = kmalloc(sizeof(*fpid), GFP_KERNEL);

	if (!fpid)

		goto out_put;



	list_add(&fpid->list, &ftrace_pids);

	fpid->pid = pid;



	set_ftrace_pid_task(pid);



	ftrace_update_pid_func();

	ftrace_startup_enable(0);



	mutex_unlock(&ftrace_lock);

	return 0;



out_put:

	if (pid != ftrace_swapper_pid)

		put_pid(pid);



out:

	mutex_unlock(&ftrace_lock);

	return ret;

}



static void ftrace_pid_reset(void)

{

	struct ftrace_pid *fpid, *safe;



	mutex_lock(&ftrace_lock);

	list_for_each_entry_safe(fpid, safe, &ftrace_pids, list) {

		struct pid *pid = fpid->pid;



		clear_ftrace_pid_task(pid);



		list_del(&fpid->list);

		kfree(fpid);

	}



	ftrace_update_pid_func();

	ftrace_startup_enable(0);



	mutex_unlock(&ftrace_lock);

}



static void *fpid_start(struct seq_file *m, loff_t *pos)

{

	mutex_lock(&ftrace_lock);



	if (list_empty(&ftrace_pids) && (!*pos))

		return (void *) 1;



	return seq_list_start(&ftrace_pids, *pos);

}



static void *fpid_next(struct seq_file *m, void *v, loff_t *pos)

{

	if (v == (void *)1)

		return NULL;



	return seq_list_next(v, &ftrace_pids, pos);

}



static void fpid_stop(struct seq_file *m, void *p)

{

	mutex_unlock(&ftrace_lock);

}



static int fpid_show(struct seq_file *m, void *v)

{

	const struct ftrace_pid *fpid = list_entry(v, struct ftrace_pid, list);



	if (v == (void *)1) {

		seq_printf(m, "no pid\n");

		return 0;

	}



	if (fpid->pid == ftrace_swapper_pid)

		seq_printf(m, "swapper tasks\n");

	else

		seq_printf(m, "%u\n", pid_vnr(fpid->pid));



	return 0;

}



static const struct seq_operations ftrace_pid_sops = {

	.start = fpid_start,

	.next = fpid_next,

	.stop = fpid_stop,

	.show = fpid_show,

};



static int

ftrace_pid_open(struct inode *inode, struct file *file)

{

	int ret = 0;



	if ((file->f_mode & FMODE_WRITE) &&

	    (file->f_flags & O_TRUNC))

		ftrace_pid_reset();



	if (file->f_mode & FMODE_READ)

		ret = seq_open(file, &ftrace_pid_sops);



	return ret;

}



static ssize_t

ftrace_pid_write(struct file *filp, const char __user *ubuf,

		   size_t cnt, loff_t *ppos)

{

	struct pid *pid;

	char buf[64];

	long val;

	int ret;
@@ -2860,57 +2975,38 @@ ftrace_pid_write(struct file *filp, const char __user *ubuf, 


	buf[cnt] = 0;



	/*

	 * Allow "echo > set_ftrace_pid" or "echo -n '' > set_ftrace_pid"

	 * to clean the filter quietly.

	 */

	strstrip(buf);

	if (strlen(buf) == 0)

		return 1;



	ret = strict_strtol(buf, 10, &val);

	if (ret < 0)

		return ret;



	mutex_lock(&ftrace_lock);

	if (val < 0) {

		/* disable pid tracing */

		if (!ftrace_pid_trace)

			goto out;



		clear_ftrace_pid_task(&ftrace_pid_trace);



	} else {

		/* swapper task is special */

		if (!val) {

			pid = ftrace_swapper_pid;

			if (pid == ftrace_pid_trace)

				goto out;

		} else {

			pid = find_get_pid(val);



			if (pid == ftrace_pid_trace) {

				put_pid(pid);

				goto out;

			}

		}



		if (ftrace_pid_trace)

			clear_ftrace_pid_task(&ftrace_pid_trace);

	ret = ftrace_pid_add(val);



		if (!pid)

			goto out;



		ftrace_pid_trace = pid;



		set_ftrace_pid_task(ftrace_pid_trace);

	return ret ? ret : cnt;

}



	/* update the function call */

	ftrace_update_pid_func();

	ftrace_startup_enable(0);



 out:

	mutex_unlock(&ftrace_lock);

static int

ftrace_pid_release(struct inode *inode, struct file *file)

{

	if (file->f_mode & FMODE_READ)

		seq_release(inode, file);



	return cnt;

	return 0;

}



static const struct file_operations ftrace_pid_fops = {

	.read = ftrace_pid_read,

	.open		= ftrace_pid_open,

	.write		= ftrace_pid_write,

	.read		= seq_read,

	.llseek		= seq_lseek,

	.release	= ftrace_pid_release,

};



static __init int ftrace_init_debugfs(void)

kernel/trace/trace.h

+2 −2
Original line number Diff line number Diff line
@@ -496,12 +496,12 @@ print_graph_function(struct trace_iterator *iter) 
}

#endif /* CONFIG_FUNCTION_GRAPH_TRACER */



extern struct pid *ftrace_pid_trace;

extern struct list_head ftrace_pids;



#ifdef CONFIG_FUNCTION_TRACER

static inline int ftrace_trace_task(struct task_struct *task)

{

	if (!ftrace_pid_trace)

	if (list_empty(&ftrace_pids))

		return 1;



	return test_tsk_trace_trace(task);

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