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nvme: fix nvme_ns_remove() deadlock 

On receipt of a namespace attribute changed AER, we acquire the
namespace mutex lock before proceeding to scan and validate the
namespace list. In case of namespace detach/delete command,
nvme_ns_remove function deadlocks trying to acquire the already held
lock.

All callers, except nvme_remove_namespaces(), of nvme_ns_remove()
already held namespaces_mutex. So we can simply fix the deadlock by
not acquiring the mutex in nvme_ns_remove() and acquiring it in
nvme_remove_namespaces().

Reported-by: Sunad Bhandary S <sunad.s@samsung.com>
Signed-off-by: Ming Lin <ming.l@ssi.samsung.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Keith Busch <keith.busch@intel.com>
Reviewed-by: Sagi Grimerg <sagi@grimberg.me>
Signed-off-by: Jens Axboe <axboe@fb.com>
This commit is contained in:
Ming Lin 2016-04-25 14:20:19 -07:00 committed by Jens Axboe
parent 0bf77e9dbb
commit b7b9c22787
1 changed files with 4 additions and 2 deletions
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6
drivers/nvme/host/core.c
View File

@ -1452,6 +1452,8 @@ static void nvme_alloc_ns(struct nvme_ctrl *ctrl, unsigned nsid)
static void nvme_ns_remove(struct nvme_ns *ns)
{
lockdep_assert_held(&ns->ctrl->namespaces_mutex);
if (test_and_set_bit(NVME_NS_REMOVING, &ns->flags))
return;
@ -1464,9 +1466,7 @@ static void nvme_ns_remove(struct nvme_ns *ns)
blk_mq_abort_requeue_list(ns->queue);
blk_cleanup_queue(ns->queue);
}
mutex_lock(&ns->ctrl->namespaces_mutex);
list_del_init(&ns->list);
mutex_unlock(&ns->ctrl->namespaces_mutex);
synchronize_rcu();
nvme_put_ns(ns);
}
@ -1580,8 +1580,10 @@ void nvme_remove_namespaces(struct nvme_ctrl *ctrl)
{
struct nvme_ns *ns, *next;
mutex_lock(&ctrl->namespaces_mutex);
list_for_each_entry_safe(ns, next, &ctrl->namespaces, list)
nvme_ns_remove(ns);
mutex_unlock(&ctrl->namespaces_mutex);
}
EXPORT_SYMBOL_GPL(nvme_remove_namespaces);