ftrace: Fix ftrace_trace_task return value (c58b6b03) · Commits · 戴 / test

I was attempting to use pid filtering with function_graph, but it wasn't allowing anything to make it through. Turns out ftrace_trace_task returns false if ftrace_ignore_pid is not-empty, which isn't correct anymore. We're now setting it to FTRACE_PID_IGNORE if we need to ignore that pid, otherwise it's set to the pid (which is weird considering the name) or to FTRACE_PID_TRACE. Fix the check to check for != FTRACE_PID_IGNORE. With this we can now use function_graph with pid filtering. Link: https://lkml.kernel.org/r/20200725005048.1790-1-josef@toxicpanda.com Fixes: ("ftrace: Make function trace pid filtering a bit more exact") Signed-off-by:

Josef Bacik <josef@toxicpanda.com> Signed-off-by:

Steven Rostedt (VMware) <rostedt@goodmis.org>

kernel/trace/ftrace.c

+0 −3

Original line number	Diff line number	Diff line
		@@ -139,9 +139,6 @@ static inline void ftrace_ops_init(struct ftrace_ops *ops)
		#endif
		}

		#define FTRACE_PID_IGNORE -1
		#define FTRACE_PID_TRACE -2

		static void ftrace_pid_func(unsigned long ip, unsigned long parent_ip,
		struct ftrace_ops op, struct pt_regs regs)
		{

kernel/trace/trace.h

+6 −1

Original line number	Diff line number	Diff line
		@@ -1103,6 +1103,10 @@ print_graph_function_flags(struct trace_iterator *iter, u32 flags)
		extern struct list_head ftrace_pids;

		#ifdef CONFIG_FUNCTION_TRACER

		#define FTRACE_PID_IGNORE -1
		#define FTRACE_PID_TRACE -2

		struct ftrace_func_command {
		struct list_head list;
		char *name;
		@@ -1114,7 +1118,8 @@ struct ftrace_func_command {
		extern bool ftrace_filter_param __initdata;
		static inline int ftrace_trace_task(struct trace_array *tr)
		{
		return !this_cpu_read(tr->array_buffer.data->ftrace_ignore_pid);
		return this_cpu_read(tr->array_buffer.data->ftrace_ignore_pid) !=
		FTRACE_PID_IGNORE;
		}
		extern int ftrace_is_dead(void);
		int ftrace_create_function_files(struct trace_array *tr,

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