nvmet-loop: Flush nvme_delete_wq when removing the port

nvmet-loop: Flush nvme_delete_wq when removing the port

[ Upstream commit 86b9a63e595ff03f9d0a7b92b6acc231fecefc29 ]

After calling nvme_loop_delete_ctrl(), the controllers will not
yet be deleted because nvme_delete_ctrl() only schedules work
to do the delete.

This means a race can occur if a port is removed but there
are still active controllers trying to access that memory.

To fix this, flush the nvme_delete_wq before returning from
nvme_loop_remove_port() so that any controllers that might
be in the process of being deleted won't access a freed port.

Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Max Gurtovoy <maxg@mellanox.com>
Reviewed-by : Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Sasha Levin <sashal@kernel.org>