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Commit 978f3a45 authored by Steven Rostedt's avatar Steven Rostedt Committed by Ingo Molnar
Browse files

ftrace: use struct pid 



Impact: clean up, extend PID filtering to PID namespaces

Eric Biederman suggested using the struct pid for filtering on
pids in the kernel. This patch is based off of a demonstration
of an implementation that Eric sent me in an email.

Signed-off-by: default avatarSteven Rostedt <srostedt@redhat.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 5ef64761

kernel/trace/ftrace.c

+44 −32
Original line number Diff line number Diff line
@@ -48,7 +48,7 @@ int ftrace_enabled __read_mostly; 
static int last_ftrace_enabled;



/* set when tracing only a pid */

int ftrace_pid_trace = -1;

struct pid *ftrace_pid_trace;



/* Quick disabling of function tracer. */

int function_trace_stop;
@@ -153,7 +153,7 @@ static int __register_ftrace_function(struct ftrace_ops *ops) 
		else

			func = ftrace_list_func;



		if (ftrace_pid_trace >= 0) {

		if (ftrace_pid_trace) {

			set_ftrace_pid_function(func);

			func = ftrace_pid_func;

		}
@@ -209,7 +209,7 @@ 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 >= 0) {

			if (ftrace_pid_trace) {

				set_ftrace_pid_function(func);

				func = ftrace_pid_func;

			}
@@ -239,7 +239,7 @@ static void ftrace_update_pid_func(void) 


	func = ftrace_trace_function;



	if (ftrace_pid_trace >= 0) {

	if (ftrace_pid_trace) {

		set_ftrace_pid_function(func);

		func = ftrace_pid_func;

	} else {
@@ -1678,18 +1678,40 @@ ftrace_pid_read(struct file *file, char __user *ubuf, 
	char buf[64];

	int r;



	if (ftrace_pid_trace >= 0)

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

	if (ftrace_pid_trace)

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

	else

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



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

}



static void clear_ftrace_pid_task(struct pid **pid)

{

	struct task_struct *p;



	do_each_pid_task(*pid, PIDTYPE_PID, p) {

		clear_tsk_trace_trace(p);

	} while_each_pid_task(*pid, PIDTYPE_PID, p);

	put_pid(*pid);



	*pid = NULL;

}



static void set_ftrace_pid_task(struct pid *pid)

{

	struct task_struct *p;



	do_each_pid_task(pid, PIDTYPE_PID, p) {

		set_tsk_trace_trace(p);

	} while_each_pid_task(pid, PIDTYPE_PID, p);

}



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;
@@ -1707,40 +1729,30 @@ ftrace_pid_write(struct file *filp, const char __user *ubuf, 
		return ret;



	mutex_lock(&ftrace_start_lock);

	if (ret < 0) {

	if (val < 0) {

		/* disable pid tracing */

		if (ftrace_pid_trace < 0)

		if (!ftrace_pid_trace)

			goto out;

		ftrace_pid_trace = -1;



		clear_ftrace_pid_task(&ftrace_pid_trace);



	} else {

		struct task_struct *p;

		int found = 0;

		pid = find_get_pid(val);



		if (ftrace_pid_trace == val)

		if (pid == ftrace_pid_trace) {

			put_pid(pid);

			goto out;



		/*

		 * Find the task that matches this pid.

		 * TODO: use pid namespaces instead.

		 */

		rcu_read_lock();

		for_each_process(p) {

			if (p->pid == val) {

				found = 1;

				set_tsk_trace_trace(p);

			} else if (test_tsk_trace_trace(p))

				clear_tsk_trace_trace(p);

		}

		rcu_read_unlock();



		if (found)

			ftrace_pid_trace = val;

		else {

			if (ftrace_pid_trace < 0)

		if (ftrace_pid_trace)

			clear_ftrace_pid_task(&ftrace_pid_trace);



		if (!pid)

			goto out;

			ftrace_pid_trace = -1;

		}



		ftrace_pid_trace = pid;



		set_ftrace_pid_task(ftrace_pid_trace);

	}



	/* update the function call */

kernel/trace/trace.h

+2 −2
Original line number Diff line number Diff line
@@ -541,11 +541,11 @@ print_graph_function(struct trace_iterator *iter) 
}

#endif /* CONFIG_FUNCTION_GRAPH_TRACER */



extern int ftrace_pid_trace;

extern struct pid *ftrace_pid_trace;



static inline int ftrace_trace_task(struct task_struct *task)

{

	if (ftrace_pid_trace < 0)

	if (ftrace_pid_trace)

		return 1;



	return test_tsk_trace_trace(task);