nvme-pci: avoid dereference of symbol from unloaded module
authorMing Lei <ming.lei@redhat.com>
Thu, 9 Nov 2017 11:32:07 +0000 (19:32 +0800)
committerJens Axboe <axboe@kernel.dk>
Sat, 11 Nov 2017 02:53:25 +0000 (19:53 -0700)
commit03e0f3a65e4da497c3b7b213c68943cbc73a2e34
tree0eff01e06d1998f467cfff23abaebba9316b77c6
parente3d7874dcf175cca2dca7795d6453f637ad8ba9b
nvme-pci: avoid dereference of symbol from unloaded module

The 'remove_work' may be scheduled to run after nvme_remove()
returns since we can't simply cancel it in nvme_remove() for
avoiding deadlock. Once nvme_remove() returns, this module(nvme)
can be unloaded.

On the other hand, nvme_put_ctrl() calls ctr->ops->free_ctrl
which may point to nvme_pci_free_ctrl() in unloaded module.

This patch avoids this issue by queuing 'remove_work' via 'nvme_wq',
and flush this worqueue in nvme_exit() as suggested by Sagi.

Suggested-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Keith Busch <keith.busch@intel.com>
Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
drivers/nvme/host/pci.c