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: Jiri Olsa <jolsa@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
LKML-Reference: <20091013203425.565454612@goodmis.org>
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index f22a7ac..acef8b4 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -496,12 +496,12 @@
}
#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);