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Commit 1e10486f authored by Namhyung Kim's avatar Namhyung Kim Committed by Steven Rostedt (VMware)
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ftrace: Add 'function-fork' trace option 

The function-fork option is same as event-fork that it tracks task
fork/exit and set the pid filter properly.  This can be useful if user
wants to trace selected tasks including their children only.

Link: http://lkml.kernel.org/r/20170417024430.21194-3-namhyung@kernel.org



Signed-off-by: default avatarNamhyung Kim <namhyung@kernel.org>
Signed-off-by: default avatarSteven Rostedt (VMware) <rostedt@goodmis.org>
parent b980b117

kernel/trace/ftrace.c

+37 −0
Original line number Diff line number Diff line
@@ -5600,6 +5600,43 @@ ftrace_filter_pid_sched_switch_probe(void *data, bool preempt, 
		       trace_ignore_this_task(pid_list, next));

}



static void

ftrace_pid_follow_sched_process_fork(void *data,

				     struct task_struct *self,

				     struct task_struct *task)

{

	struct trace_pid_list *pid_list;

	struct trace_array *tr = data;



	pid_list = rcu_dereference_sched(tr->function_pids);

	trace_filter_add_remove_task(pid_list, self, task);

}



static void

ftrace_pid_follow_sched_process_exit(void *data, struct task_struct *task)

{

	struct trace_pid_list *pid_list;

	struct trace_array *tr = data;



	pid_list = rcu_dereference_sched(tr->function_pids);

	trace_filter_add_remove_task(pid_list, NULL, task);

}



void ftrace_pid_follow_fork(struct trace_array *tr, bool enable)

{

	if (enable) {

		register_trace_sched_process_fork(ftrace_pid_follow_sched_process_fork,

						  tr);

		register_trace_sched_process_exit(ftrace_pid_follow_sched_process_exit,

						  tr);

	} else {

		unregister_trace_sched_process_fork(ftrace_pid_follow_sched_process_fork,

						    tr);

		unregister_trace_sched_process_exit(ftrace_pid_follow_sched_process_exit,

						    tr);

	}

}



static void clear_ftrace_pids(struct trace_array *tr)

{

	struct trace_pid_list *pid_list;

kernel/trace/trace.c

+4 −1
Original line number Diff line number Diff line
@@ -257,7 +257,7 @@ unsigned long long ns2usecs(u64 nsec) 


/* trace_flags that are default zero for instances */

#define ZEROED_TRACE_FLAGS \

	TRACE_ITER_EVENT_FORK

	(TRACE_ITER_EVENT_FORK | TRACE_ITER_FUNC_FORK)



/*

 * The global_trace is the descriptor that holds the top-level tracing
@@ -4205,6 +4205,9 @@ int set_tracer_flag(struct trace_array *tr, unsigned int mask, int enabled) 
	if (mask == TRACE_ITER_EVENT_FORK)

		trace_event_follow_fork(tr, enabled);



	if (mask == TRACE_ITER_FUNC_FORK)

		ftrace_pid_follow_fork(tr, enabled);



	if (mask == TRACE_ITER_OVERWRITE) {

		ring_buffer_change_overwrite(tr->trace_buffer.buffer, enabled);

#ifdef CONFIG_TRACER_MAX_TRACE

kernel/trace/trace.h

+5 −1
Original line number Diff line number Diff line
@@ -897,6 +897,7 @@ void ftrace_init_tracefs(struct trace_array *tr, struct dentry *d_tracer); 
void ftrace_init_tracefs_toplevel(struct trace_array *tr,

				  struct dentry *d_tracer);

int init_function_trace(void);

void ftrace_pid_follow_fork(struct trace_array *tr, bool enable);

#else

static inline int ftrace_trace_task(struct trace_array *tr)

{
@@ -916,6 +917,7 @@ static inline void ftrace_reset_array_ops(struct trace_array *tr) { } 
static inline void ftrace_init_tracefs(struct trace_array *tr, struct dentry *d) { }

static inline void ftrace_init_tracefs_toplevel(struct trace_array *tr, struct dentry *d) { }

static inline int init_function_trace(void) { return 0; }

static inline void ftrace_pid_follow_fork(struct trace_array *tr, bool enable) { }

/* ftace_func_t type is not defined, use macro instead of static inline */

#define ftrace_init_array_ops(tr, func) do { } while (0)

#endif /* CONFIG_FUNCTION_TRACER */
@@ -989,11 +991,13 @@ extern int trace_get_user(struct trace_parser *parser, const char __user *ubuf, 


#ifdef CONFIG_FUNCTION_TRACER

# define FUNCTION_FLAGS						\

		C(FUNCTION,		"function-trace"),

		C(FUNCTION,		"function-trace"),	\

		C(FUNC_FORK,		"function-fork"),

# define FUNCTION_DEFAULT_FLAGS		TRACE_ITER_FUNCTION

#else

# define FUNCTION_FLAGS

# define FUNCTION_DEFAULT_FLAGS		0UL

# define TRACE_ITER_FUNC_FORK		0UL

#endif



#ifdef CONFIG_STACKTRACE