Commit c7a60a73 authored by Steven Rostedt's avatar Steven Rostedt Committed by Steven Rostedt (Google)
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ftrace: Have funcgraph-args take affect during tracing 

Currently, when function_graph is started, it looks at the option
funcgraph-args, and if it is set, it will enable tracing of the arguments.

But if tracing is already running, and the user enables funcgraph-args, it
will have no effect. Instead, it should enable argument tracing when it is
enabled, even if it means disabling the function graph tracing for a short
time in order to do the transition.

Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Sven Schnelle <svens@linux.ibm.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Palmer Dabbelt <palmer@dabbelt.com>
Cc: Albert Ou <aou@eecs.berkeley.edu>
Cc: Guo Ren <guoren@kernel.org>
Cc: Donglin Peng <dolinux.peng@gmail.com>
Cc: Zheng Yejian <zhengyejian@huaweicloud.com>
Link: https://lore.kernel.org/20250227185822.978998710@goodmis.org


Acked-by: default avatarMasami Hiramatsu (Google) <mhiramat@kernel.org>
Signed-off-by: default avatarSteven Rostedt (Google) <rostedt@goodmis.org>
parent ff5c9c57

kernel/trace/trace_functions_graph.c

+26 −1
Original line number Diff line number Diff line
@@ -464,7 +464,7 @@ static int graph_trace_init(struct trace_array *tr) 
	else

		tr->gops->retfunc = trace_graph_return;



	/* Make gops functions are visible before we start tracing */

	/* Make gops functions visible before we start tracing */

	smp_mb();



	ret = register_ftrace_graph(tr->gops);
@@ -475,6 +475,28 @@ static int graph_trace_init(struct trace_array *tr) 
	return 0;

}



static int ftrace_graph_trace_args(struct trace_array *tr, int set)

{

	trace_func_graph_ent_t entry;



	if (set)

		entry = trace_graph_entry_args;

	else

		entry = trace_graph_entry;



	/* See if there's any changes */

	if (tr->gops->entryfunc == entry)

		return 0;



	unregister_ftrace_graph(tr->gops);



	tr->gops->entryfunc = entry;



	/* Make gops functions visible before we start tracing */

	smp_mb();

	return register_ftrace_graph(tr->gops);

}



static void graph_trace_reset(struct trace_array *tr)

{

	tracing_stop_cmdline_record();
@@ -1607,6 +1629,9 @@ func_graph_set_flag(struct trace_array *tr, u32 old_flags, u32 bit, int set) 
	if (bit == TRACE_GRAPH_GRAPH_TIME)

		ftrace_graph_graph_time_control(set);



	if (bit == TRACE_GRAPH_ARGS)

		return ftrace_graph_trace_args(tr, set);



	return 0;

}