On 8/22/24 07:19, Steven Rostedt wrote:
On Wed, 21 Aug 2024 21:54:42 -0600
Shuah Khan <skhan@xxxxxxxxxxxxxxxxxxx> wrote:
On 8/21/24 13:09, Steven Rostedt wrote:
From: Steven Rostedt <rostedt@xxxxxxxxxxx>
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@devnote2
Signed-off-by: Steven Rostedt (Google) <rostedt@xxxxxxxxxxx>
---
.../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@xxxxxxxxxxxxxxxxxxx>
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.
No need for a v2
thanks,
-- Shuah
