From 765cc031cddde40bdc279e8e2697571c7956c54e Mon Sep 17 00:00:00 2001 From: Jianchao Wang Date: Mon, 12 Feb 2018 20:54:46 +0800 Subject: nvme: change namespaces_mutext to namespaces_rwsem namespaces_mutext is used to synchronize the operations on ctrl namespaces list. Most of the time, it is a read operation. On the other hand, there are many interfaces in nvme core that need this lock, such as nvme_wait_freeze, and even more interfaces will be added. If we use mutex here, circular dependency could be introduced easily. For example: context A context B nvme_xxx nvme_xxx hold namespaces_mutext require namespaces_mutext sync context B So it is better to change it from mutex to rwsem. Reviewed-by: Keith Busch Signed-off-by: Jianchao Wang Signed-off-by: Sagi Grimberg Signed-off-by: Jens Axboe --- drivers/nvme/host/core.c | 64 +++++++++++++++++++++---------------------- drivers/nvme/host/multipath.c | 4 +-- drivers/nvme/host/nvme.h | 2 +- 3 files changed, 35 insertions(+), 35 deletions(-) (limited to 'drivers/nvme') diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c index 31f20f4643cf..ea99265565ae 100644 --- a/drivers/nvme/host/core.c +++ b/drivers/nvme/host/core.c @@ -1125,13 +1125,13 @@ static void nvme_update_formats(struct nvme_ctrl *ctrl) struct nvme_ns *ns, *next; LIST_HEAD(rm_list); - mutex_lock(&ctrl->namespaces_mutex); + down_write(&ctrl->namespaces_rwsem); list_for_each_entry(ns, &ctrl->namespaces, list) { if (ns->disk && nvme_revalidate_disk(ns->disk)) { list_move_tail(&ns->list, &rm_list); } } - mutex_unlock(&ctrl->namespaces_mutex); + up_write(&ctrl->namespaces_rwsem); list_for_each_entry_safe(ns, next, &rm_list, list) nvme_ns_remove(ns); @@ -2441,7 +2441,7 @@ static int nvme_dev_user_cmd(struct nvme_ctrl *ctrl, void __user *argp) struct nvme_ns *ns; int ret; - mutex_lock(&ctrl->namespaces_mutex); + down_read(&ctrl->namespaces_rwsem); if (list_empty(&ctrl->namespaces)) { ret = -ENOTTY; goto out_unlock; @@ -2458,14 +2458,14 @@ static int nvme_dev_user_cmd(struct nvme_ctrl *ctrl, void __user *argp) dev_warn(ctrl->device, "using deprecated NVME_IOCTL_IO_CMD ioctl on the char device!\n"); kref_get(&ns->kref); - mutex_unlock(&ctrl->namespaces_mutex); + up_read(&ctrl->namespaces_rwsem); ret = nvme_user_cmd(ctrl, ns, argp); nvme_put_ns(ns); return ret; out_unlock: - mutex_unlock(&ctrl->namespaces_mutex); + up_read(&ctrl->namespaces_rwsem); return ret; } @@ -2894,7 +2894,7 @@ static struct nvme_ns *nvme_find_get_ns(struct nvme_ctrl *ctrl, unsigned nsid) { struct nvme_ns *ns, *ret = NULL; - mutex_lock(&ctrl->namespaces_mutex); + down_read(&ctrl->namespaces_rwsem); list_for_each_entry(ns, &ctrl->namespaces, list) { if (ns->head->ns_id == nsid) { if (!kref_get_unless_zero(&ns->kref)) @@ -2905,7 +2905,7 @@ static struct nvme_ns *nvme_find_get_ns(struct nvme_ctrl *ctrl, unsigned nsid) if (ns->head->ns_id > nsid) break; } - mutex_unlock(&ctrl->namespaces_mutex); + up_read(&ctrl->namespaces_rwsem); return ret; } @@ -3016,9 +3016,9 @@ static void nvme_alloc_ns(struct nvme_ctrl *ctrl, unsigned nsid) __nvme_revalidate_disk(disk, id); - mutex_lock(&ctrl->namespaces_mutex); + down_write(&ctrl->namespaces_rwsem); list_add_tail(&ns->list, &ctrl->namespaces); - mutex_unlock(&ctrl->namespaces_mutex); + up_write(&ctrl->namespaces_rwsem); nvme_get_ctrl(ctrl); @@ -3072,9 +3072,9 @@ static void nvme_ns_remove(struct nvme_ns *ns) list_del_rcu(&ns->siblings); mutex_unlock(&ns->ctrl->subsys->lock); - mutex_lock(&ns->ctrl->namespaces_mutex); + down_write(&ns->ctrl->namespaces_rwsem); list_del_init(&ns->list); - mutex_unlock(&ns->ctrl->namespaces_mutex); + up_write(&ns->ctrl->namespaces_rwsem); synchronize_srcu(&ns->head->srcu); nvme_mpath_check_last_path(ns); @@ -3100,12 +3100,12 @@ static void nvme_remove_invalid_namespaces(struct nvme_ctrl *ctrl, struct nvme_ns *ns, *next; LIST_HEAD(rm_list); - mutex_lock(&ctrl->namespaces_mutex); + down_write(&ctrl->namespaces_rwsem); list_for_each_entry_safe(ns, next, &ctrl->namespaces, list) { if (ns->head->ns_id > nsid) list_move_tail(&ns->list, &rm_list); } - mutex_unlock(&ctrl->namespaces_mutex); + up_write(&ctrl->namespaces_rwsem); list_for_each_entry_safe(ns, next, &rm_list, list) nvme_ns_remove(ns); @@ -3185,9 +3185,9 @@ static void nvme_scan_work(struct work_struct *work) } nvme_scan_ns_sequential(ctrl, nn); done: - mutex_lock(&ctrl->namespaces_mutex); + down_write(&ctrl->namespaces_rwsem); list_sort(NULL, &ctrl->namespaces, ns_cmp); - mutex_unlock(&ctrl->namespaces_mutex); + up_write(&ctrl->namespaces_rwsem); kfree(id); } @@ -3220,9 +3220,9 @@ void nvme_remove_namespaces(struct nvme_ctrl *ctrl) if (ctrl->state == NVME_CTRL_DEAD) nvme_kill_queues(ctrl); - mutex_lock(&ctrl->namespaces_mutex); + down_write(&ctrl->namespaces_rwsem); list_splice_init(&ctrl->namespaces, &ns_list); - mutex_unlock(&ctrl->namespaces_mutex); + up_write(&ctrl->namespaces_rwsem); list_for_each_entry_safe(ns, next, &ns_list, list) nvme_ns_remove(ns); @@ -3411,7 +3411,7 @@ int nvme_init_ctrl(struct nvme_ctrl *ctrl, struct device *dev, ctrl->state = NVME_CTRL_NEW; spin_lock_init(&ctrl->lock); INIT_LIST_HEAD(&ctrl->namespaces); - mutex_init(&ctrl->namespaces_mutex); + init_rwsem(&ctrl->namespaces_rwsem); ctrl->dev = dev; ctrl->ops = ops; ctrl->quirks = quirks; @@ -3472,7 +3472,7 @@ void nvme_kill_queues(struct nvme_ctrl *ctrl) { struct nvme_ns *ns; - mutex_lock(&ctrl->namespaces_mutex); + down_read(&ctrl->namespaces_rwsem); /* Forcibly unquiesce queues to avoid blocking dispatch */ if (ctrl->admin_q) @@ -3491,7 +3491,7 @@ void nvme_kill_queues(struct nvme_ctrl *ctrl) /* Forcibly unquiesce queues to avoid blocking dispatch */ blk_mq_unquiesce_queue(ns->queue); } - mutex_unlock(&ctrl->namespaces_mutex); + up_read(&ctrl->namespaces_rwsem); } EXPORT_SYMBOL_GPL(nvme_kill_queues); @@ -3499,10 +3499,10 @@ void nvme_unfreeze(struct nvme_ctrl *ctrl) { struct nvme_ns *ns; - mutex_lock(&ctrl->namespaces_mutex); + down_read(&ctrl->namespaces_rwsem); list_for_each_entry(ns, &ctrl->namespaces, list) blk_mq_unfreeze_queue(ns->queue); - mutex_unlock(&ctrl->namespaces_mutex); + up_read(&ctrl->namespaces_rwsem); } EXPORT_SYMBOL_GPL(nvme_unfreeze); @@ -3510,13 +3510,13 @@ void nvme_wait_freeze_timeout(struct nvme_ctrl *ctrl, long timeout) { struct nvme_ns *ns; - mutex_lock(&ctrl->namespaces_mutex); + down_read(&ctrl->namespaces_rwsem); list_for_each_entry(ns, &ctrl->namespaces, list) { timeout = blk_mq_freeze_queue_wait_timeout(ns->queue, timeout); if (timeout <= 0) break; } - mutex_unlock(&ctrl->namespaces_mutex); + up_read(&ctrl->namespaces_rwsem); } EXPORT_SYMBOL_GPL(nvme_wait_freeze_timeout); @@ -3524,10 +3524,10 @@ void nvme_wait_freeze(struct nvme_ctrl *ctrl) { struct nvme_ns *ns; - mutex_lock(&ctrl->namespaces_mutex); + down_read(&ctrl->namespaces_rwsem); list_for_each_entry(ns, &ctrl->namespaces, list) blk_mq_freeze_queue_wait(ns->queue); - mutex_unlock(&ctrl->namespaces_mutex); + up_read(&ctrl->namespaces_rwsem); } EXPORT_SYMBOL_GPL(nvme_wait_freeze); @@ -3535,10 +3535,10 @@ void nvme_start_freeze(struct nvme_ctrl *ctrl) { struct nvme_ns *ns; - mutex_lock(&ctrl->namespaces_mutex); + down_read(&ctrl->namespaces_rwsem); list_for_each_entry(ns, &ctrl->namespaces, list) blk_freeze_queue_start(ns->queue); - mutex_unlock(&ctrl->namespaces_mutex); + up_read(&ctrl->namespaces_rwsem); } EXPORT_SYMBOL_GPL(nvme_start_freeze); @@ -3546,10 +3546,10 @@ void nvme_stop_queues(struct nvme_ctrl *ctrl) { struct nvme_ns *ns; - mutex_lock(&ctrl->namespaces_mutex); + down_read(&ctrl->namespaces_rwsem); list_for_each_entry(ns, &ctrl->namespaces, list) blk_mq_quiesce_queue(ns->queue); - mutex_unlock(&ctrl->namespaces_mutex); + up_read(&ctrl->namespaces_rwsem); } EXPORT_SYMBOL_GPL(nvme_stop_queues); @@ -3557,10 +3557,10 @@ void nvme_start_queues(struct nvme_ctrl *ctrl) { struct nvme_ns *ns; - mutex_lock(&ctrl->namespaces_mutex); + down_read(&ctrl->namespaces_rwsem); list_for_each_entry(ns, &ctrl->namespaces, list) blk_mq_unquiesce_queue(ns->queue); - mutex_unlock(&ctrl->namespaces_mutex); + up_read(&ctrl->namespaces_rwsem); } EXPORT_SYMBOL_GPL(nvme_start_queues); diff --git a/drivers/nvme/host/multipath.c b/drivers/nvme/host/multipath.c index 7283d7149baf..affd67021b6f 100644 --- a/drivers/nvme/host/multipath.c +++ b/drivers/nvme/host/multipath.c @@ -44,12 +44,12 @@ void nvme_kick_requeue_lists(struct nvme_ctrl *ctrl) { struct nvme_ns *ns; - mutex_lock(&ctrl->namespaces_mutex); + down_read(&ctrl->namespaces_rwsem); list_for_each_entry(ns, &ctrl->namespaces, list) { if (ns->head->disk) kblockd_schedule_work(&ns->head->requeue_work); } - mutex_unlock(&ctrl->namespaces_mutex); + up_read(&ctrl->namespaces_rwsem); } static struct nvme_ns *__nvme_find_path(struct nvme_ns_head *head) diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h index 9a3d3540aa6a..29942b1892f7 100644 --- a/drivers/nvme/host/nvme.h +++ b/drivers/nvme/host/nvme.h @@ -141,7 +141,7 @@ struct nvme_ctrl { struct blk_mq_tag_set *tagset; struct blk_mq_tag_set *admin_tagset; struct list_head namespaces; - struct mutex namespaces_mutex; + struct rw_semaphore namespaces_rwsem; struct device ctrl_device; struct device *device; /* char device */ struct cdev cdev; -- cgit v1.2.3