selftests/damon/_debugfs_common: hide expected error message from test_write_result()

DAMON debugfs interface selftests use test_write_result() to check if
valid or invalid writes to files of the interface success or fail as
expected.  File write error messages from expected failures are only
making the output noisy.  Hide such expected error messages.

Link: https://lkml.kernel.org/r/20241028233058.283381-4-sj@kernel.org
Fixes: b348eb7abd09 ("mm/damon: add user space selftests")
Signed-off-by: SeongJae Park <sj@kernel.org>
Cc: Andrew Paniakin <apanyaki@amazon.com>
Cc: Brendan Higgins <brendan.higgins@linux.dev>
Cc: David Gow <davidgow@google.com>
Cc: Shuah Khan <shuah@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/tools/testing/selftests/damon/_debugfs_common.sh b/tools/testing/selftests/damon/_debugfs_common.sh
index aa995516870bc8c4e0fe70d5dda6d6257c990470..54d45791b0d9cb8875956bb0aa89471244e40686 100644 (file)
--- a/tools/testing/selftests/damon/_debugfs_common.sh
+++ b/tools/testing/selftests/damon/_debugfs_common.sh
@@ -8,7 +8,12 @@ test_write_result() {
        expect_reason=$4
        expected=$5
 
-       echo "$content" > "$file"
+       if [ "$expected" = "0" ]
+       then
+               echo "$content" > "$file"
+       else
+               echo "$content" > "$file" 2> /dev/null
+       fi
        if [ $? -ne "$expected" ]
        then
                echo "writing $content to $file doesn't return $expected"