[PATCH v2 1/2] nvme: switch to RCU freeing the namespace
Keith Busch
keith.busch at intel.com
Tue May 17 08:23:59 PDT 2016
On Tue, May 17, 2016 at 11:05:11AM -0400, Keith Busch wrote:
> Today, though, the driver has newer checks so it doesn't crash when
> blk-mq submits a command the driver can't handle. If we change the nvme
> pci driver's nvme_queue_rq to stop hw queues before returning
> BLK_MQ_RQ_QUEUE_BUSY (scsi_queue_rq() in scsi_lib.c might be a good
> example), we could skip cancelling requeue work in "nvme_stop_queues()"
> if we're sure it won't race with the reset work's nvme_start_queues().
Untested patch below:
---
diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index 643f457..13d3cf9 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -1552,7 +1552,6 @@ void nvme_stop_queues(struct nvme_ctrl *ctrl)
queue_flag_set(QUEUE_FLAG_STOPPED, ns->queue);
spin_unlock_irq(ns->queue->queue_lock);
- blk_mq_cancel_requeue_work(ns->queue);
blk_mq_stop_hw_queues(ns->queue);
}
mutex_unlock(&ctrl->namespaces_mutex);
@@ -1565,7 +1564,10 @@ void nvme_start_queues(struct nvme_ctrl *ctrl)
mutex_lock(&ctrl->namespaces_mutex);
list_for_each_entry(ns, &ctrl->namespaces, list) {
- queue_flag_clear_unlocked(QUEUE_FLAG_STOPPED, ns->queue);
+ spin_lock_irq(ns->queue->queue_lock);
+ queue_flag_clear(QUEUE_FLAG_STOPPED, ns->queue);
+ spin_unlock_irq(ns->queue->queue_lock);
+
blk_mq_start_stopped_hw_queues(ns->queue, true);
blk_mq_kick_requeue_list(ns->queue);
}
diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index 4fd733f..b65d7d6 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -690,6 +690,12 @@ static int nvme_queue_rq(struct blk_mq_hw_ctx *hctx,
spin_unlock_irq(&nvmeq->q_lock);
return BLK_MQ_RQ_QUEUE_OK;
out:
+ if (ret == BLK_MQ_RQ_QUEUE_BUSY) {
+ spin_lock_irq(ns->queue->queue_lock);
+ if (!blk_queue_stopped(req->q))
+ blk_mq_stop_hw_queues(ns->queue);
+ spin_unlock_irq(ns->queue->queue_lock);
+ }
nvme_free_iod(dev, req);
return ret;
}
--
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