function_graph: Add pid tracing back to function graph tracer

Now that the function_graph has a main callback that handles the function
graph subops tracing, it no longer honors the pid filtering of ftrace. Add
back this logic in the function_graph code to update the gops callback for
the entry function to test if it should trace the current task or not.

Link: https://lore.kernel.org/linux-trace-kernel/20240603190822.991720703@goodmis.org

Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Alexei Starovoitov <alexei.starovoitov@gmail.com>
Cc: Florent Revest <revest@chromium.org>
Cc: Martin KaFai Lau <martin.lau@linux.dev>
Cc: bpf <bpf@vger.kernel.org>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Alexei Starovoitov <ast@kernel.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Arnaldo Carvalho de Melo <acme@kernel.org>
Cc: Daniel Borkmann <daniel@iogearbox.net>
Cc: Alan Maguire <alan.maguire@oracle.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Guo Ren <guoren@kernel.org>
Reviewed-by: Masami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

1 files changed, 3 insertions, 2 deletions

diff --git a/kernel/trace/ftrace.c b/kernel/trace/ftrace.c
index 58e0f4bc0241..da7e6abf48b4 100644
--- a/kernel/trace/ftrace.c
+++ b/kernel/trace/ftrace.c
@@ -100,7 +100,7 @@ struct ftrace_ops *function_trace_op __read_mostly = &ftrace_list_end;
 /* What to set function_trace_op to */
 static struct ftrace_ops *set_function_trace_op;
 
-static bool ftrace_pids_enabled(struct ftrace_ops *ops)
+bool ftrace_pids_enabled(struct ftrace_ops *ops)
 {
 	struct trace_array *tr;
 
@@ -402,10 +402,11 @@ static void ftrace_update_pid_func(void)
 		if (op->flags & FTRACE_OPS_FL_PID) {
 			op->func = ftrace_pids_enabled(op) ?
 				ftrace_pid_func : op->saved_func;
-			ftrace_update_trampoline(op);
 		}
 	} while_for_each_ftrace_op(op);
 
+	fgraph_update_pid_func();
+
 	update_ftrace_function();
 }