[PATCH 6.18 126/227] selftests/ublk: fix garbage output in foreground mode

Greg Kroah-Hartman
2026-01-28T15:57:11Z

From: Ming Lei <ming.lei@redhat.com>

[ Upstream commit e7e1cc18f120a415646be12470169a978a1adcd9 ]

Initialize _evtfd to -1 in struct dev_ctx to prevent garbage output
when running kublk in foreground mode. Without this, _evtfd is
zero-initialized to 0 (stdin), and ublk_send_dev_event() writes
binary data to stdin which appears as garbage on the terminal.

Also fix debug message format string.

Fixes: 6aecda00b7d1 ("selftests: ublk: add kernel selftests for ublk")
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Caleb Sander Mateos <csander@purestorage.com>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
tools/testing/selftests/ublk/kublk.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/tools/testing/selftests/ublk/kublk.c b/tools/testing/selftests/ublk/kublk.c
index 9c05f046ad5ee..cbd23444c8a98 100644
--- a/tools/testing/selftests/ublk/kublk.c
+++ b/tools/testing/selftests/ublk/kublk.c
@@ -1221,7 +1221,7 @@ static int __cmd_dev_add(const struct dev_ctx *ctx)
}

ret = ublk_start_daemon(ctx, dev);
- ublk_dbg(UBLK_DBG_DEV, "%s: daemon exit %d\b", ret);
+ ublk_dbg(UBLK_DBG_DEV, "%s: daemon exit %d\n", __func__, ret);
if (ret < 0)
ublk_ctrl_del_dev(dev);

@@ -1566,6 +1566,7 @@ int main(int argc, char *argv[])
int option_idx, opt;
const char *cmd = argv[1];
struct dev_ctx ctx = {
+ ._evtfd = -1,
.queue_depth = 128,
.nr_hw_queues = 2,
.dev_id = -1,
--
2.51.0