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author | Steven Rostedt <rostedt@goodmis.org> | 2016-04-13 16:59:18 -0400 |
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committer | Steven Rostedt <rostedt@goodmis.org> | 2016-04-19 10:28:28 -0400 |
commit | c37775d57830a36382a9774bb84eca4ce3d019cc (patch) | |
tree | 460e9b501ee496689da8ecb84290b7f2d32c91e6 /kernel/trace/trace_events.c | |
parent | f4d34a87e9c10f0ffd03d3548db6bfb200d06cdf (diff) | |
download | linux-c37775d57830a36382a9774bb84eca4ce3d019cc.tar.gz linux-c37775d57830a36382a9774bb84eca4ce3d019cc.tar.bz2 linux-c37775d57830a36382a9774bb84eca4ce3d019cc.zip |
tracing: Add infrastructure to allow set_event_pid to follow children
Add the infrastructure needed to have the PIDs in set_event_pid to
automatically add PIDs of the children of the tasks that have their PIDs in
set_event_pid. This will also remove PIDs from set_event_pid when a task
exits
This is implemented by adding hooks into the fork and exit tracepoints. On
fork, the PIDs are added to the list, and on exit, they are removed.
Add a new option called event_fork that when set, PIDs in set_event_pid will
automatically get their children PIDs added when they fork, as well as any
task that exits will have its PID removed from set_event_pid.
This works for instances as well.
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Diffstat (limited to 'kernel/trace/trace_events.c')
-rw-r--r-- | kernel/trace/trace_events.c | 84 |
1 files changed, 74 insertions, 10 deletions
diff --git a/kernel/trace/trace_events.c b/kernel/trace/trace_events.c index 45f7cc72bf25..add81dff7520 100644 --- a/kernel/trace/trace_events.c +++ b/kernel/trace/trace_events.c @@ -474,11 +474,23 @@ static void ftrace_clear_events(struct trace_array *tr) /* Shouldn't this be in a header? */ extern int pid_max; +/* Returns true if found in filter */ static bool -ignore_this_task(struct trace_pid_list *filtered_pids, struct task_struct *task) +find_filtered_pid(struct trace_pid_list *filtered_pids, pid_t search_pid) { - pid_t pid; + /* + * If pid_max changed after filtered_pids was created, we + * by default ignore all pids greater than the previous pid_max. + */ + if (search_pid >= filtered_pids->pid_max) + return false; + + return test_bit(search_pid, filtered_pids->pids); +} +static bool +ignore_this_task(struct trace_pid_list *filtered_pids, struct task_struct *task) +{ /* * Return false, because if filtered_pids does not exist, * all pids are good to trace. @@ -486,16 +498,68 @@ ignore_this_task(struct trace_pid_list *filtered_pids, struct task_struct *task) if (!filtered_pids) return false; - pid = task->pid; + return !find_filtered_pid(filtered_pids, task->pid); +} - /* - * If pid_max changed after filtered_pids was created, we - * by default ignore all pids greater than the previous pid_max. - */ - if (task->pid >= filtered_pids->pid_max) - return true; +static void filter_add_remove_task(struct trace_pid_list *pid_list, + struct task_struct *self, + struct task_struct *task) +{ + if (!pid_list) + return; + + /* For forks, we only add if the forking task is listed */ + if (self) { + if (!find_filtered_pid(pid_list, self->pid)) + return; + } + + /* Sorry, but we don't support pid_max changing after setting */ + if (task->pid >= pid_list->pid_max) + return; + + /* "self" is set for forks, and NULL for exits */ + if (self) + set_bit(task->pid, pid_list->pids); + else + clear_bit(task->pid, pid_list->pids); +} + +static void +event_filter_pid_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->filtered_pids); + filter_add_remove_task(pid_list, NULL, task); +} - return !test_bit(task->pid, filtered_pids->pids); +static void +event_filter_pid_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->filtered_pids); + filter_add_remove_task(pid_list, self, task); +} + +void trace_event_follow_fork(struct trace_array *tr, bool enable) +{ + if (enable) { + register_trace_prio_sched_process_fork(event_filter_pid_sched_process_fork, + tr, INT_MIN); + register_trace_prio_sched_process_exit(event_filter_pid_sched_process_exit, + tr, INT_MAX); + } else { + unregister_trace_sched_process_fork(event_filter_pid_sched_process_fork, + tr); + unregister_trace_sched_process_exit(event_filter_pid_sched_process_exit, + tr); + } } static void |