diff mbox series

fgraph: Fix set_graph_notrace with setting TRACE_GRAPH_NOTRACE_BIT

Message ID 20250208001511.535be150@batman.local.home (mailing list archive)
State Accepted
Commit c8c9b1d2d5b4377c72a979f5a26e842a869aefc9
Headers show
Series fgraph: Fix set_graph_notrace with setting TRACE_GRAPH_NOTRACE_BIT | expand

Commit Message

Steven Rostedt Feb. 8, 2025, 5:15 a.m. UTC 
From: Steven Rostedt <rostedt@goodmis.org>

The code was restructured where the function graph notrace code, that
would not trace a function and all its children is done by setting a
NOTRACE flag when the function that is not to be traced is hit.

There's a TRACE_GRAPH_NOTRACE_BIT which defines the bit in the flags and a
TRACE_GRAPH_NOTRACE which is the mask with that bit set. But the
restructuring used TRACE_GRAPH_NOTRACE_BIT when it should have used
TRACE_GRAPH_NOTRACE.

For example:

 # cd /sys/kernel/tracing
 # echo set_track_prepare stack_trace_save  > set_graph_notrace
 # echo function_graph > current_tracer
 # cat trace
[..]
 0)               |                          __slab_free() {
 0)               |                            free_to_partial_list() {
 0)               |                                  arch_stack_walk() {
 0)               |                                    __unwind_start() {
 0)   0.501 us    |                                      get_stack_info();

Where a non filter trace looks like:

 # echo > set_graph_notrace
 # cat trace
 0)               |                            free_to_partial_list() {
 0)               |                              set_track_prepare() {
 0)               |                                stack_trace_save() {
 0)               |                                  arch_stack_walk() {
 0)               |                                    __unwind_start() {

Where the filter should look like:

 # cat trace
 0)               |                            free_to_partial_list() {
 0)               |                              _raw_spin_lock_irqsave() {
 0)   0.350 us    |                                preempt_count_add();
 0)   0.351 us    |                                do_raw_spin_lock();
 0)   2.440 us    |                              }

Fixes: b84214890a9bc ("function_graph: Move graph notrace bit to shadow stack global var")
Signed-off-by: Steven Rostedt (Google) <rostedt@goodmis.org>
---
 kernel/trace/trace_functions_graph.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
diff mbox series

Patch

diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index 54d850997c0a..136c750b0b4d 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -198,7 +198,7 @@  int trace_graph_entry(struct ftrace_graph_ent *trace,
 	 * returning from the function.
 	 */
 	if (ftrace_graph_notrace_addr(trace->func)) {
-		*task_var |= TRACE_GRAPH_NOTRACE_BIT;
+		*task_var |= TRACE_GRAPH_NOTRACE;
 		/*
 		 * Need to return 1 to have the return called
 		 * that will clear the NOTRACE bit.