[PATCH] selftests/ftrace: Fix reading enabled_functions in add_remove_fprobe_module test
From: Steven Rostedt <rostedt@goodmis.org>
Date: 2026-07-08 19:32:44
Also in:
linux-kselftest, lkml
Subsystem:
kernel selftest framework, the rest, tracing · Maintainers:
Shuah Khan, Linus Torvalds, Steven Rostedt, Masami Hiramatsu
From: Steven Rostedt <rostedt@goodmis.org> The add_remove_fprobe_module test checks the number of functions added to the enabled_functions file to make sure that the functions added or removed is as expected. The issue is that it expects this file to be empty on start up. Now that systemd uses BPF that attaches to functions via ftrace, this file is not empty in several systems: # cat /sys/kernel/tracing/enabled_functions bpf_lsm_file_open (1) R D M tramp: ftrace_regs_caller+0x0/0x61 (call_direct_funcs+0x0/0x50) direct(jmp)-->bpf_trampoline_6442529439+0x0/0xe9 Change the test to read the number of lines in enabled_functions at the start of the test and subtract that from the value of the count for the checks within the test. Signed-off-by: Steven Rostedt <rostedt@goodmis.org> --- .../dynevent/add_remove_fprobe_module.tc | 27 ++++++++++++------- 1 file changed, 18 insertions(+), 9 deletions(-)
diff --git a/tools/testing/selftests/ftrace/test.d/dynevent/add_remove_fprobe_module.tc b/tools/testing/selftests/ftrace/test.d/dynevent/add_remove_fprobe_module.tc
index 2915206777b6..89660a9adf44 100644
--- a/tools/testing/selftests/ftrace/test.d/dynevent/add_remove_fprobe_module.tc
+++ b/tools/testing/selftests/ftrace/test.d/dynevent/add_remove_fprobe_module.tc@@ -16,23 +16,32 @@ echo > dynamic_events FUNC1='foo_bar*' FUNC2='vfs_read' +:;: "Save enabled functions count" ;: +ecount=`cat enabled_functions | wc -l` + +count_enabled_functions() { + count=`cat enabled_functions | wc -l` + count=$(($count-$ecount)) + echo $count +} + :;: "Add an event on the test module" ;: echo "f:test1 $FUNC1" >> dynamic_events echo 1 > events/fprobes/test1/enable :;: "Ensure it is enabled" ;: -funcs=`cat enabled_functions | wc -l` +funcs=`count_enabled_functions` test $funcs -ne 0 :;: "Check the enabled_functions is cleared on unloading" ;: rmmod trace-events-sample -funcs=`cat enabled_functions | wc -l` +funcs=`count_enabled_functions` test $funcs -eq 0 :;: "Check it is kept clean" ;: modprobe trace-events-sample echo 1 > events/fprobes/test1/enable || echo "OK" -funcs=`cat enabled_functions | wc -l` +funcs=`count_enabled_functions` test $funcs -eq 0 :;: "Add another event not on the test module" ;:
@@ -40,19 +49,19 @@ echo "f:test2 $FUNC2" >> dynamic_events echo 1 > events/fprobes/test2/enable :;: "Ensure it is enabled" ;: -ofuncs=`cat enabled_functions | wc -l` +ofuncs=`count_enabled_functions` test $ofuncs -ne 0 :;: "Disable and remove the first event" echo 0 > events/fprobes/test1/enable echo "-:fprobes/test1" >> dynamic_events -funcs=`cat enabled_functions | wc -l` +funcs=`count_enabled_functions` test $ofuncs -eq $funcs :;: "Disable and remove other events" ;: echo 0 > events/fprobes/enable echo > dynamic_events -funcs=`cat enabled_functions | wc -l` +funcs=`count_enabled_functions` test $funcs -eq 0 rmmod trace-events-sample
@@ -63,12 +72,12 @@ echo "f:test1 $FUNC1" >> dynamic_events echo 1 > events/fprobes/test1/enable echo "f:test2 $FUNC2" >> dynamic_events echo 1 > events/fprobes/test2/enable -ofuncs=`cat enabled_functions | wc -l` +ofuncs=`count_enabled_functions` test $ofuncs -ne 0 :;: "Unload module (ftrace entry should be removed)" ;: rmmod trace-events-sample -funcs=`cat enabled_functions | wc -l` +funcs=`count_enabled_functions` test $funcs -ne 0 test $ofuncs -ne $funcs
@@ -77,7 +86,7 @@ echo 0 > events/fprobes/test2/enable echo "-:fprobes/test2" >> dynamic_events :;: "Ensure ftrace is disabled." ;: -funcs=`cat enabled_functions | wc -l` +funcs=`count_enabled_functions` test $funcs -eq 0 echo 0 > events/fprobes/enable
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2.53.0