[PATCH] selftests: ublk: fix unused_result error

[Dirk Gouders <dirk@gouders.net>]

Commit 166b476b8dee (selftests/ublk: add shared memory zero-copy
support in kublk, 2026-03-31) introduced a write(2), ignoring its
return value and thus causing an error, when building.

Fix this by using the common workaround "(void)!" to trick the
compiler the result is being used.

Signed-off-by: Dirk Gouders <dirk@gouders.net>
---
 tools/testing/selftests/ublk/kublk.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/tools/testing/selftests/ublk/kublk.c b/tools/testing/selftests/ublk/kublk.c
index 2400b4615766..5b19bfcfa8d7 100644
--- a/tools/testing/selftests/ublk/kublk.c
+++ b/tools/testing/selftests/ublk/kublk.c
@@ -1589,7 +1589,7 @@ static int ublk_start_daemon(const struct dev_ctx *ctx, struct ublk_dev *dev)
 
 	/* Signal listener thread to stop and wait for it */
 	if (linfo.stop_efd >= 0) {
-		write(linfo.stop_efd, &stop_val, sizeof(stop_val));
+		(void)!write(linfo.stop_efd, &stop_val, sizeof(stop_val));
 		pthread_join(listener, NULL);
 		close(linfo.stop_efd);
 		ublk_shmem_sock_destroy(dinfo->dev_id, linfo.sock_fd);
-- 
2.55.0