Commit dbc635c4 authored by Ming Lei's avatar Ming Lei Committed by Jens Axboe
Browse files

ublk: move ublk_mark_io_ready() out of __ublk_fetch() 



ublk_batch_prep_io() calls __ublk_fetch() while holding io->lock
spinlock. When the last IO makes the device ready, ublk_mark_io_ready()
tries to acquire ub->cancel_mutex which can sleep, causing a
sleeping-while-atomic bug.

Fix by moving ublk_mark_io_ready() out of __ublk_fetch() and into the
callers (ublk_fetch and ublk_batch_prep_io) after the spinlock is
released.

Reported-by: default avatarJens Axboe <axboe@kernel.dk>
Fixes: b256795b ("ublk: handle UBLK_U_IO_PREP_IO_CMDS")
Signed-off-by: default avatarMing Lei <ming.lei@redhat.com>
Signed-off-by: default avatarJens Axboe <axboe@kernel.dk>
parent e8cd481c

drivers/block/ublk_drv.c

+5 −1
Original line number Diff line number Diff line
@@ -3064,7 +3064,6 @@ static int __ublk_fetch(struct io_uring_cmd *cmd, struct ublk_device *ub, 
		WRITE_ONCE(io->task, NULL);

	else

		WRITE_ONCE(io->task, get_task_struct(current));

	ublk_mark_io_ready(ub, q_id);



	return 0;

}
@@ -3083,6 +3082,8 @@ static int ublk_fetch(struct io_uring_cmd *cmd, struct ublk_device *ub, 
	ret = __ublk_fetch(cmd, ub, io, q_id);

	if (!ret)

		ret = ublk_config_io_buf(ub, io, cmd, buf_addr, NULL);

	if (!ret)

		ublk_mark_io_ready(ub, q_id);

	mutex_unlock(&ub->mutex);

	return ret;

}
@@ -3484,6 +3485,9 @@ static int ublk_batch_prep_io(struct ublk_queue *ubq, 
		io->buf = buf;

	ublk_io_unlock(io);



	if (!ret)

		ublk_mark_io_ready(data->ub, ubq->q_id);



	return ret;

}