On Wed, 21 Aug 2024 21:54:42 -0600 Shuah Khan skhan@linuxfoundation.org wrote:
On 8/21/24 13:09, Steven Rostedt wrote:
From: Steven Rostedt rostedt@goodmis.org
Masami reported a bug when running function graph tracing then the function profiler. The following commands would cause a kernel crash:
# cd /sys/kernel/tracing/ # echo function_graph > current_tracer # echo 1 > function_profile_enabled
In that order. Create a test to test this two to make sure this does not come back as a regression.
Link: https://lore.kernel.org/172398528350.293426.8347220120333730248.stgit@devnot...
Signed-off-by: Steven Rostedt (Google) rostedt@goodmis.org
.../ftrace/test.d/ftrace/fgraph-profiler.tc | 30 +++++++++++++++++++ 1 file changed, 30 insertions(+) create mode 100644 tools/testing/selftests/ftrace/test.d/ftrace/fgraph-profiler.tc
diff --git a/tools/testing/selftests/ftrace/test.d/ftrace/fgraph-profiler.tc b/tools/testing/selftests/ftrace/test.d/ftrace/fgraph-profiler.tc new file mode 100644 index 000000000000..62d44a1395da --- /dev/null +++ b/tools/testing/selftests/ftrace/test.d/ftrace/fgraph-profiler.tc @@ -0,0 +1,30 @@ +#!/bin/sh +# SPDX-License-Identifier: GPL-2.0 +# description: ftrace - function profiler with function graph tracing +# requires: function_profile_enabled set_ftrace_filter function_graph:tracer
+# The function graph tracer can now be run along side of the function +# profiler. But there was a bug that caused the combination of the two +# to crash. It also required the function graph tracer to be started +# first. +# +# This test triggers that bug +# +# We need function_graph and profiling to to run this test
+fail() { # mesg
- echo $1
- exit_fail
+}
+echo "Enabling function graph tracer:" +echo function_graph > current_tracer +echo "enable profiler"
+# Older kernels do not allow function_profile to be enabled with +# function graph tracer. If the below fails, mark it as unsupported +echo 1 > function_profile_enabled || exit_unsupported
+sleep 1
Any specific reason for this sleep 1 - can you add a comment on top?
We add sleep 1 in several locations of the ftrace selftests to let the tracing run for a bit just to see if it triggers anything. Otherwise the clean up can happen before anything gets traced. Although, it's highly unlikely in this case, but still.
I could add a comment if you want of just:
# let it run for a bit sleep 1
+exit 0
Reviewed-by: Shuah Khan skhan@linuxfoundation.org
Let me know if you would like v2 for this to be taken through my tree.
I'll make a v2 if you want me to.
-- Steve