From 646017a612e72f19bd9f991fe25287a149c5f627 Mon Sep 17 00:00:00 2001 From: Keith Busch Date: Wed, 24 Feb 2016 09:15:54 -0700 Subject: NVMe: Fix namespace removal deadlock This patch makes nvme namespace removal lockless. It is up to the caller to ensure no active namespace scanning is occuring. To ensure no scan work occurs, the nvme pci driver adds a removing state to the controller device to avoid queueing scan work during removal. The work is flushed after setting the state, so no new scan work can be queued. The lockless removal allows the driver to cleanup a namespace request_queue if the controller fails during removal. Previously this could deadlock trying to acquire the namespace mutex in order to handle such events. Signed-off-by: Keith Busch Reviewed-by: Johannes Thumshirn Reviewed-by: Christoph Hellwig Signed-off-by: Jens Axboe --- drivers/nvme/host/core.c | 12 +++++++----- drivers/nvme/host/nvme.h | 4 ++++ drivers/nvme/host/pci.c | 17 +++++++++++++++-- 3 files changed, 26 insertions(+), 7 deletions(-) (limited to 'drivers/nvme') diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c index 6c39dbf0290f..8c2ddd5025ab 100644 --- a/drivers/nvme/host/core.c +++ b/drivers/nvme/host/core.c @@ -1186,11 +1186,13 @@ static void nvme_alloc_ns(struct nvme_ctrl *ctrl, unsigned nsid) static void nvme_ns_remove(struct nvme_ns *ns) { - bool kill = nvme_io_incapable(ns->ctrl) && - !blk_queue_dying(ns->queue); + bool kill; - lockdep_assert_held(&ns->ctrl->namespaces_mutex); + if (test_and_set_bit(NVME_NS_REMOVING, &ns->flags)) + return; + kill = nvme_io_incapable(ns->ctrl) && + !blk_queue_dying(ns->queue); if (kill) { blk_set_queue_dying(ns->queue); @@ -1213,7 +1215,9 @@ 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); } @@ -1307,10 +1311,8 @@ 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); } static DEFINE_IDA(nvme_instance_ida); diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h index 9407f2fa4487..4075fa9e0c34 100644 --- a/drivers/nvme/host/nvme.h +++ b/drivers/nvme/host/nvme.h @@ -114,6 +114,10 @@ struct nvme_ns { bool ext; u8 pi_type; int type; + unsigned long flags; + +#define NVME_NS_REMOVING 0 + u64 mode_select_num_blocks; u32 mode_select_block_len; }; diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c index 2ea3e398536c..122f803f0efb 100644 --- a/drivers/nvme/host/pci.c +++ b/drivers/nvme/host/pci.c @@ -120,6 +120,7 @@ struct nvme_dev { unsigned long flags; #define NVME_CTRL_RESETTING 0 +#define NVME_CTRL_REMOVING 1 struct nvme_ctrl ctrl; struct completion ioq_wait; @@ -286,6 +287,17 @@ static int nvme_init_request(void *data, struct request *req, return 0; } +static void nvme_queue_scan(struct nvme_dev *dev) +{ + /* + * Do not queue new scan work when a controller is reset during + * removal. + */ + if (test_bit(NVME_CTRL_REMOVING, &dev->flags)) + return; + queue_work(nvme_workq, &dev->scan_work); +} + static void nvme_complete_async_event(struct nvme_dev *dev, struct nvme_completion *cqe) { @@ -300,7 +312,7 @@ static void nvme_complete_async_event(struct nvme_dev *dev, switch (result & 0xff07) { case NVME_AER_NOTICE_NS_CHANGED: dev_info(dev->dev, "rescanning\n"); - queue_work(nvme_workq, &dev->scan_work); + nvme_queue_scan(dev); default: dev_warn(dev->dev, "async event result %08x\n", result); } @@ -1690,7 +1702,7 @@ static int nvme_dev_add(struct nvme_dev *dev) return 0; dev->ctrl.tagset = &dev->tagset; } - queue_work(nvme_workq, &dev->scan_work); + nvme_queue_scan(dev); return 0; } @@ -2128,6 +2140,7 @@ static void nvme_remove(struct pci_dev *pdev) { struct nvme_dev *dev = pci_get_drvdata(pdev); + set_bit(NVME_CTRL_REMOVING, &dev->flags); pci_set_drvdata(pdev, NULL); flush_work(&dev->scan_work); nvme_remove_namespaces(&dev->ctrl); -- cgit v1.2.3