[PATCH v3] rcutorture: Copy out ftrace into its own console file

[Joel Fernandes (Google)]

When debugging, it can be difficult to quickly find the ftrace dump
within the console log, which in turn makes it difficult to process it
independent of the result of the console output.  This commit therefore
copies the contents of the buffers into its own file to make it easier
to locate and process the ftrace dump. The original ftrace dump is still
available in the console log in cases where it is more convenient to
process it there, for example, when you have a script that processes
console output as well as ftrace-dump data.

Also handle the case of multiple ftrace dumps potentially showing up in the
log. Example for a file like [1], it will extract as [2].

[1]:
foo
foo
Dumping ftrace buffer:
---------------------------------
blah
blah
---------------------------------
more
bar
baz
Dumping ftrace buffer:
---------------------------------
blah2
blah2
---------------------------------
bleh
bleh

[2]:

Ftrace dump 1:
blah
blah

Ftrace dump 2:
blah2
blah2


Signed-off-by: Joel Fernandes (Google) <joel@xxxxxxxxxxxxxxxxx>
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxx>
---
v2->v3: Updates from Paul. Also handle multiple ftrace dumps.

 .../selftests/rcutorture/bin/functions.sh     | 24 +++++++++++++++++++
 .../selftests/rcutorture/bin/parse-console.sh |  7 ++++++
 2 files changed, 31 insertions(+)
 mode change 100644 => 100755 tools/testing/selftests/rcutorture/bin/functions.sh

diff --git a/tools/testing/selftests/rcutorture/bin/functions.sh b/tools/testing/selftests/rcutorture/bin/functions.sh
old mode 100644
new mode 100755
index b8e2ea23cb3f..a5c74e508e41
--- a/tools/testing/selftests/rcutorture/bin/functions.sh
+++ b/tools/testing/selftests/rcutorture/bin/functions.sh
@@ -331,3 +331,30 @@ specify_qemu_net () {
 		echo $1 -net none
 	fi
 }
+
+# Extract the ftrace output from the console log output
+# The ftrace output in the original logs look like:
+# Dumping ftrace buffer:
+# ---------------------------------
+# [...]
+# ---------------------------------
+extract_ftrace_from_console() {
+        awk '
+        /Dumping ftrace buffer:/ {
+        buffer_count++
+        print "Ftrace dump " buffer_count ":"
+        capture = 1
+        next
+    }
+    /---------------------------------/ {
+        if(capture == 1) {
+            capture = 2
+            next
+        } else if(capture == 2) {
+            capture = 0
+            print ""
+        }
+    }
+    capture == 2
+    ' "$1";
+}
diff --git a/tools/testing/selftests/rcutorture/bin/parse-console.sh b/tools/testing/selftests/rcutorture/bin/parse-console.sh
index 9ab0f6bc172c..e3d2f69ec0fb 100755
--- a/tools/testing/selftests/rcutorture/bin/parse-console.sh
+++ b/tools/testing/selftests/rcutorture/bin/parse-console.sh
@@ -182,3 +182,10 @@ if ! test -s $file.diags
 then
 	rm -f $file.diags
 fi
+
+# Call extract_ftrace_from_console function, if the output is empty,
+# don't create $file.ftrace. Otherwise output the results to $file.ftrace
+extract_ftrace_from_console $file > $file.ftrace
+if [ ! -s $file.ftrace ]; then
+	rm -f $file.ftrace
+fi
-- 
2.41.0.694.ge786442a9b-goog