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ftrace: Add 'function-fork' trace option

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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: Namhyung Kim <namhyung@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
This commit is contained in:
Namhyung Kim 2017-04-17 11:44:28 +09:00 committed by Steven Rostedt (VMware)
parent b980b117c9
commit 1e10486ffe
3 changed files with 46 additions and 2 deletions
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37
kernel/trace/ftrace.c
View File

@ -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;

5
kernel/trace/trace.c
View File

@ -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

6
kernel/trace/trace.h
View File

@ -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