[PATCH] mm/damon/sysfs: do not ignore callback's return value in damon_sysfs_damon_call()

[Akinobu Mita <akinobu.mita@gmail.com>]

The callback return value is ignored in damon_sysfs_damon_call(), which
means that it is not possible to detect invalid user input when writing
commands such as 'commit' to /sys/kernel/mm/damon/admin/kdamonds/<K>/state.
Fix it.

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
---
 mm/damon/sysfs.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/mm/damon/sysfs.c b/mm/damon/sysfs.c
index fe4e73d0ebbb..97e16f00f23e 100644
--- a/mm/damon/sysfs.c
+++ b/mm/damon/sysfs.c
@@ -1627,12 +1627,15 @@ static int damon_sysfs_damon_call(int (*fn)(void *data),
 		struct damon_sysfs_kdamond *kdamond)
 {
 	struct damon_call_control call_control = {};
+	int err;
 
 	if (!kdamond->damon_ctx)
 		return -EINVAL;
 	call_control.fn = fn;
 	call_control.data = kdamond;
-	return damon_call(kdamond->damon_ctx, &call_control);
+	err = damon_call(kdamond->damon_ctx, &call_control);
+
+	return err ? err : call_control.return_code;
 }
 
 struct damon_sysfs_schemes_walk_data {
-- 
2.43.0