Messages in this thread Patch in this message | | | Date | Wed, 19 Oct 2022 15:15:09 +0530 | From | "Naveen N. Rao" <> | Subject | Re: [PATCH] selftests/ftrace: Limit number of lines processed in 'trace' |
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Steven Rostedt wrote: > On Wed, 19 Oct 2022 00:19:49 +0900 > Masami Hiramatsu (Google) <mhiramat@kernel.org> wrote: > >> > You need to make sure that the "pause-on-trace" option is set or tracing_on >> > is set to 0 (disabled). Otherwise, if the tracing is still active, then the >> > reading of the trace file could potentially never end. >> >> initialize_ftrace() does this setting. So it must be set. >> If you run the ftracetest on old kernel, this feature is not there and >> it may cause a trouble. Naveen, can you clarify it?
Yes, the change to not pause on opening the trace file looks to be the problem.
> > But for old kernels that do not have "pause-on-trace" it should be the > default. The "pause-on-trace" was added when the default was changed to not > pause the trace while reading it.
It looks like the kernel patch was picked up, but Masami's patch for the selftest wasn't backported. I have requested a test with that applied.
Separately, before I saw your response, I came up with the below patch to update the selftests to disable tracing before reading the trace file. I have also requested this to be tested.
- Naveen
--- .../selftests/ftrace/test.d/ftrace/fgraph-filter-stack.tc | 4 +++- tools/testing/selftests/ftrace/test.d/ftrace/fgraph-filter.tc | 2 ++ .../selftests/ftrace/test.d/ftrace/func-filter-notrace-pid.tc | 3 ++- .../testing/selftests/ftrace/test.d/ftrace/func-filter-pid.tc | 3 ++- 4 files changed, 9 insertions(+), 3 deletions(-)
diff --git a/tools/testing/selftests/ftrace/test.d/ftrace/fgraph-filter-stack.tc b/tools/testing/selftests/ftrace/test.d/ftrace/fgraph-filter-stack.tc index cf3ea42b12b09f..7e74df1ef928f9 100644 --- a/tools/testing/selftests/ftrace/test.d/ftrace/fgraph-filter-stack.tc +++ b/tools/testing/selftests/ftrace/test.d/ftrace/fgraph-filter-stack.tc @@ -39,6 +39,7 @@ disable_tracing clear_trace enable_tracing sleep 1 +disable_tracing count=`cat trace | grep '()' | grep -v schedule | wc -l` @@ -54,8 +55,9 @@ fi echo 0 > /proc/sys/kernel/stack_tracer_enabled clear_trace +enable_tracing sleep 1 - +disable_tracing count=`cat trace | grep '()' | grep -v schedule | wc -l` diff --git a/tools/testing/selftests/ftrace/test.d/ftrace/fgraph-filter.tc b/tools/testing/selftests/ftrace/test.d/ftrace/fgraph-filter.tc index b3ccdaec2a61ba..7e65a115054127 100644 --- a/tools/testing/selftests/ftrace/test.d/ftrace/fgraph-filter.tc +++ b/tools/testing/selftests/ftrace/test.d/ftrace/fgraph-filter.tc @@ -24,6 +24,8 @@ fi echo function_graph > current_tracer enable_tracing sleep 1 +disable_tracing + # search for functions (has "()" on the line), and make sure # that only the schedule function was found count=`cat trace | grep '()' | grep -v schedule | wc -l` diff --git a/tools/testing/selftests/ftrace/test.d/ftrace/func-filter-notrace-pid.tc b/tools/testing/selftests/ftrace/test.d/ftrace/func-filter-notrace-pid.tc index 80541964b9270b..9fb0511b5d2eeb 100644 --- a/tools/testing/selftests/ftrace/test.d/ftrace/func-filter-notrace-pid.tc +++ b/tools/testing/selftests/ftrace/test.d/ftrace/func-filter-notrace-pid.tc @@ -51,6 +51,7 @@ do_test() { enable_tracing yield + disable_tracing count_pid=`cat trace | grep -v ^# | grep $PID | wc -l` count_other=`cat trace | grep -v ^# | grep -v $PID | wc -l` @@ -60,7 +61,6 @@ do_test() { fail "PID filtering not working? traced task = $count_pid; other tasks = $count_other " fi - disable_tracing clear_trace if [ $do_function_fork -eq 0 ]; then @@ -77,6 +77,7 @@ do_test() { enable_tracing yield + disable_tracing count_pid=`cat trace | grep -v ^# | grep $PID | wc -l` count_other=`cat trace | grep -v ^# | grep -v $PID | wc -l` diff --git a/tools/testing/selftests/ftrace/test.d/ftrace/func-filter-pid.tc b/tools/testing/selftests/ftrace/test.d/ftrace/func-filter-pid.tc index 2f7211254529ba..c55bcf2fe1966f 100644 --- a/tools/testing/selftests/ftrace/test.d/ftrace/func-filter-pid.tc +++ b/tools/testing/selftests/ftrace/test.d/ftrace/func-filter-pid.tc @@ -51,6 +51,7 @@ do_test() { enable_tracing yield + disable_tracing count_pid=`cat trace | grep -v ^# | grep $PID | wc -l` count_other=`cat trace | grep -v ^# | grep -v $PID | wc -l` @@ -60,7 +61,6 @@ do_test() { fail "PID filtering not working?" fi - disable_tracing clear_trace if [ $do_function_fork -eq 0 ]; then @@ -72,6 +72,7 @@ do_test() { enable_tracing yield + disable_tracing count_pid=`cat trace | grep -v ^# | grep $PID | wc -l` count_other=`cat trace | grep -v ^# | grep -v $PID | wc -l`
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