[PATCH v4 07/18] tracing/remotes: selftests: Add a test for the dmesg tracefs file

[Vincent Donnefort <vdonnefort@google.com>]

Exercise the newly introduced dmesg tracefs file that turns on and off
the dmesg redirection.

Signed-off-by: Vincent Donnefort <vdonnefort@google.com>

diff --git a/tools/testing/selftests/ftrace/test.d/remotes/dmesg.tc b/tools/testing/selftests/ftrace/test.d/remotes/dmesg.tc
new file mode 100644
index 000000000000..aebeea9dbab6
--- /dev/null
+++ b/tools/testing/selftests/ftrace/test.d/remotes/dmesg.tc
@@ -0,0 +1,72 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+# description: Test trace remote dmesg redirection
+# requires: remotes/test
+
+. $TEST_DIR/remotes/functions
+
+test_dmesg()
+{
+    echo 0 > tracing_on
+    assert_unloaded
+
+    #
+    # Test dmesg on/off when tracing is disabled
+    #
+    echo 1 > dmesg
+    test $(cat dmesg) -eq 1
+    assert_loaded
+
+    echo 0 > dmesg
+    test $(cat dmesg) -eq 0
+    assert_unloaded
+
+    #
+    # Test events are logged to dmesg
+    #
+    dmesg -c > /dev/null
+
+    echo 1 > tracing_on
+    assert_loaded
+    echo 1 > dmesg
+    test $(cat dmesg) -eq 1
+
+    nr_events=128
+    for i in $(seq 1 $nr_events); do
+        echo $i > write_event
+    done
+
+    sleep 1
+    output=$(mktemp $TMPDIR/remote_test.XXXXXX)
+    dmesg | grep "selftest id=" | sed 's/^[^]]*] //'> $output
+
+    check_trace 1 $nr_events $output
+
+    rm $output
+
+    #
+    # Disable dmesg and Test events were not consumed by dmesg
+    #
+    echo 0 > dmesg
+    test $(cat dmesg) -eq 0
+
+    start_id=$(($nr_events + 1))
+    end_id=$(($start_id + $nr_events))
+
+    for i in $(seq $start_id $end_id); do
+        echo $i > write_event
+    done
+
+    sleep 1
+
+    output=$(dump_trace_pipe)
+    check_trace $start_id $end_id $output
+    rm $output
+}
+
+if [ -z "$SOURCE_REMOTE_TEST" ]; then
+    set -e
+
+    setup_remote_test
+    test_dmesg
+fi
diff --git a/tools/testing/selftests/ftrace/test.d/remotes/functions b/tools/testing/selftests/ftrace/test.d/remotes/functions
index 05224fac3653..4a14aa72fdf0 100644
--- a/tools/testing/selftests/ftrace/test.d/remotes/functions
+++ b/tools/testing/selftests/ftrace/test.d/remotes/functions
@@ -8,6 +8,7 @@ setup_remote()
 
 	cd remotes/$name/
 	echo 0 > tracing_on
+	echo 0 > dmesg
 	clear_trace
 	echo 7 > buffer_size_kb
 	echo 0 > events/enable
diff --git a/tools/testing/selftests/ftrace/test.d/remotes/hypervisor/dmesg.tc b/tools/testing/selftests/ftrace/test.d/remotes/hypervisor/dmesg.tc
new file mode 100644
index 000000000000..bf4a3c145e7a
--- /dev/null
+++ b/tools/testing/selftests/ftrace/test.d/remotes/hypervisor/dmesg.tc
@@ -0,0 +1,11 @@
+#!/bin/sh
+# SPDX-License-Identifier: GPL-2.0
+# description: Test the hypervisor trace dmesg redirection
+# requires: remotes/hypervisor/write_event
+
+SOURCE_REMOTE_TEST=1
+. $TEST_DIR/remotes/dmesg.tc
+
+set -e
+setup_remote "hypervisor"
+test_dmesg
-- 
2.55.0.571.g244d577d93-goog