[PATCH] nvme-pci: allocate tagset on reset if necessary

[PATCH] nvme-pci: allocate tagset on reset if necessary

[Keith Busch]

From: Keith Busch <kbusch@kernel.org>

If a drive is unable to create IO queues on the initial probe, a
subsequent reset will need to allocate the tagset if IO queue creation
is successful.

Signed-off-by: Keith Busch <kbusch@kernel.org>
---
 drivers/nvme/host/pci.c | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index 6cd9395ba9ec3..8e280e13cf10d 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -2508,9 +2508,14 @@ static unsigned int nvme_pci_nr_maps(struct nvme_dev *dev)
 
 static void nvme_pci_update_nr_queues(struct nvme_dev *dev)
 {
-	blk_mq_update_nr_hw_queues(&dev->tagset, dev->online_queues - 1);
-	/* free previously allocated queues that are no longer usable */
-	nvme_free_queues(dev, dev->online_queues);
+	if (!dev->ctrl.tagset) {
+		nvme_alloc_io_tag_set(&dev->ctrl, &dev->tagset, &nvme_mq_ops,
+				nvme_pci_nr_maps(dev), sizeof(struct nvme_iod));
+	} else {
+		blk_mq_update_nr_hw_queues(&dev->tagset, dev->online_queues - 1);
+		/* free previously allocated queues that are no longer usable */
+		nvme_free_queues(dev, dev->online_queues);
+	}
 }
 
 static int nvme_pci_enable(struct nvme_dev *dev)
-- 
2.43.5

Re: [PATCH] nvme-pci: allocate tagset on reset if necessary

[Christoph Hellwig]

On Mon, Aug 26, 2024 at 11:27:19AM -0700, Keith Busch wrote:
> +	if (!dev->ctrl.tagset) {
> +		nvme_alloc_io_tag_set(&dev->ctrl, &dev->tagset, &nvme_mq_ops,
> +				nvme_pci_nr_maps(dev), sizeof(struct nvme_iod));
> +	} else {
> +		blk_mq_update_nr_hw_queues(&dev->tagset, dev->online_queues - 1);

Overly long line here.  Maybe just return early after the allocation
above?

Otherwise looks good:

Reviewed-by: Christoph Hellwig <hch@lst.de>

Re: [PATCH] nvme-pci: allocate tagset on reset if necessary

[Keith Busch]

On Tue, Aug 27, 2024 at 07:49:23AM +0200, Christoph Hellwig wrote:
> On Mon, Aug 26, 2024 at 11:27:19AM -0700, Keith Busch wrote:
> > +	if (!dev->ctrl.tagset) {
> > +		nvme_alloc_io_tag_set(&dev->ctrl, &dev->tagset, &nvme_mq_ops,
> > +				nvme_pci_nr_maps(dev), sizeof(struct nvme_iod));
> > +	} else {
> > +		blk_mq_update_nr_hw_queues(&dev->tagset, dev->online_queues - 1);
> 
> Overly long line here.  Maybe just return early after the allocation
> above?

Done.

I think I should also add more details to the change log because this
bug does cause a kernel crash. I think this is the first commit that
removed tagset allocation from reset_work:

Fixes: eac3ef262941f62 ("nvme-pci: split the initial probe from the rest path")
> 

Re: [PATCH] nvme-pci: allocate tagset on reset if necessary

[Sagi Grimberg]

Reviewed-by: Sagi Grimberg <sagi@grimberg.me>