[PATCH v2] 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>
Fixes: f64539dcdb87 ("mm/damon/sysfs: use damon_call() for update_schemes_stats")
Cc: <stable@vger.kernel.org> # v6.14.x
Reviewed-by: SeongJae Park <sj@kernel.org>
---
 mm/damon/sysfs.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/mm/damon/sysfs.c b/mm/damon/sysfs.c
index fe4e73d0ebbb..3ffe3a77b5db 100644
--- a/mm/damon/sysfs.c
+++ b/mm/damon/sysfs.c
@@ -1627,12 +1627,14 @@ 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