On Fri, Jan 19, 2018 at 04:14:02PM +0800, jianchao.wang wrote:
> On 01/19/2018 04:01 PM, Keith Busch wrote:
> > The nvme_dev_disable routine makes forward progress without depending on
> > timeout handling to complete expired commands. Once controller disabling
> > completes, there can't possibly be any started requests that can expire.
> > So we don't need nvme_timeout to do anything for requests above the
> > boundary.
> >
> Yes, once controller disabling completes, any started requests will be
> handled and cannot expire.
> But before the _boundary_, there could be a nvme_timeout context runs with
> nvme_dev_disable in parallel.
> If a timeout path grabs a request, then nvme_dev_disable cannot get and
> cancel it.
> So even though the nvme_dev_disable completes, there still could be a request
> in nvme_timeout context.
>
> The worst case is :
> nvme_timeout nvme_reset_work
> if (ctrl->state == RESETTING ) nvme_dev_disable
> nvme_dev_disable initializing procedure
>
> the nvme_dev_disable run with reinit procedure in nvme_reset_work in parallel.
Okay, I see what you're saying. That's a pretty obscure case, as normally
we enter nvme_reset_work with the queues already disabled, but there
are a few cases where we need nvme_reset_work to handle that.
But if we are in that case, I think we really just want to sync the
queues. What do you think of this?
---
diff --git a/drivers/nvme/host/core.c b/drivers/nvme/host/core.c
index fde6fd2e7eef..516383193416 100644
--- a/drivers/nvme/host/core.c
+++ b/drivers/nvme/host/core.c
@@ -3520,6 +3520,17 @@ void nvme_stop_queues(struct nvme_ctrl *ctrl)
}
EXPORT_SYMBOL_GPL(nvme_stop_queues);
+void nvme_sync_queues(struct nvme_ctrl *ctrl)
+{
+ struct nvme_ns *ns;
+
+ mutex_lock(&ctrl->namespaces_mutex);
+ list_for_each_entry(ns, &ctrl->namespaces, list)
+ blk_sync_queue(ns->queue);
+ mutex_unlock(&ctrl->namespaces_mutex);
+}
+EXPORT_SYMBOL_GPL(nvme_sync_queues);
+
void nvme_start_queues(struct nvme_ctrl *ctrl)
{
struct nvme_ns *ns;
diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index 8e7fc1b041b7..45b1b8ceddb6 100644
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -374,6 +374,7 @@ void nvme_complete_async_event(struct nvme_ctrl *ctrl,
__le16 status,
void nvme_stop_queues(struct nvme_ctrl *ctrl);
void nvme_start_queues(struct nvme_ctrl *ctrl);
+void nvme_sync_queues(struct nvme_ctrl *ctrl)
void nvme_kill_queues(struct nvme_ctrl *ctrl);
void nvme_unfreeze(struct nvme_ctrl *ctrl);
void nvme_wait_freeze(struct nvme_ctrl *ctrl);
diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index a2ffb557b616..1fe00be22ad1 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -2289,8 +2289,10 @@ static void nvme_reset_work(struct work_struct *work)
* If we're called to reset a live controller first shut it down before
* moving on.
*/
- if (dev->ctrl.ctrl_config & NVME_CC_ENABLE)
+ if (dev->ctrl.ctrl_config & NVME_CC_ENABLE) {
nvme_dev_disable(dev, false);
+ nvme_sync_queues(&dev->ctrl);
+ }
result = nvme_pci_enable(dev);
if (result)
--
