fgraph: Remove coarse PID filtering from graph_entry()

With PID filtering working via ftrace_pids_enabled() and fgraph_pid_func,
the coarse-grained ftrace_trace_task() check in graph_entry() is obsolete.

It was only a fallback for uninitialized op->private (now fixed), and its
removal ensures consistent PID filtering with standard function tracing.

Also remove unused ftrace_trace_task() definition from trace.h.

Cc: <wang.yaxin@zte.com.cn>
Cc: <mhiramat@kernel.org>
Cc: <mark.rutland@arm.com>
Cc: <mathieu.desnoyers@efficios.com>
Cc: <zhang.run@zte.com.cn>
Cc: <yang.yang29@zte.com.cn>
Link: https://patch.msgid.link/20251126173552333XoJZN20143fWbsdTEtWoU@zte.com.cn
Signed-off-by: Shengming Hu <hu.shengming@zte.com.cn>
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>

Author: HSM6236

kernel/trace/trace.h

@@ -1154,11 +1154,6 @@ struct ftrace_func_command {
 					char *params, int enable);
 };
 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) !=
-		FTRACE_PID_IGNORE;
-}
 extern int ftrace_is_dead(void);
 int ftrace_create_function_files(struct trace_array *tr,
 				 struct dentry *parent);
@@ -1176,10 +1171,6 @@ void ftrace_clear_pids(struct trace_array *tr);
 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)
-{
-	return 1;
-}
 static inline int ftrace_is_dead(void) { return 0; }
 static inline int
 ftrace_create_function_files(struct trace_array *tr,

kernel/trace/trace_functions_graph.c

@@ -232,9 +232,6 @@ static int graph_entry(struct ftrace_graph_ent *trace,
 		return 1;
 	}
 
-	if (!ftrace_trace_task(tr))
-		return 0;
-
 	if (ftrace_graph_ignore_func(gops, trace))
 		return 0;