From mboxrd@z Thu Jan 1 00:00:00 1970 From: mlin@kernel.org (Ming Lin) Date: Mon, 18 Apr 2016 11:21:43 -0700 Subject: [PATCH] nvme: fix nvme_ns_remove() deadlock Message-ID: <1461003703-18950-1-git-send-email-mlin@kernel.org> From: Ming Lin 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 Signed-off-by: Ming Lin --- drivers/nvme/host/core.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c index 7dd9905..ab00f3d 100644 --- a/drivers/nvme/host/core.c +++ b/drivers/nvme/host/core.c @@ -1410,6 +1410,8 @@ 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; @@ -1422,9 +1424,7 @@ 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); nvme_put_ns(ns); } @@ -1519,8 +1519,10 @@ 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); -- 1.9.1