[PATCH] nvme/pci: Check segement valid for SGL use

[PATCH] nvme/pci: Check segement valid for SGL use

[Keith Busch]

The driver needs to verify there is a payload with a command before
seeing if it should use SGLs to map it.

Fixes: 955b1b5a00ba ("nvme-pci: move use_sgl initialization to nvme_init_iod()")

Reported-by: Paul Menzel <pmenzel+linux-nvme at molgen.mpg.de>
Signed-off-by: Keith Busch <keith.busch at intel.com>
---
 drivers/nvme/host/pci.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index d53550e612bc..a7e94cc3c70e 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -451,10 +451,13 @@ static void **nvme_pci_iod_list(struct request *req)
 static inline bool nvme_pci_use_sgls(struct nvme_dev *dev, struct request *req)
 {
 	struct nvme_iod *iod = blk_mq_rq_to_pdu(req);
+	int nseg = blk_rq_nr_phys_segments(req);
 	unsigned int avg_seg_size;
 
-	avg_seg_size = DIV_ROUND_UP(blk_rq_payload_bytes(req),
-			blk_rq_nr_phys_segments(req));
+	if (nseg == 0)
+		return false;
+
+	avg_seg_size = DIV_ROUND_UP(blk_rq_payload_bytes(req), nseg);
 
 	if (!(dev->ctrl.sgls & ((1 << 0) | (1 << 1))))
 		return false;
-- 
2.13.6

[PATCH] nvme/pci: Check segement valid for SGL use

[Paul Menzel]

Dear Keith,


On 01/15/18 14:07, Keith Busch wrote:
> The driver needs to verify there is a payload with a command before
> seeing if it should use SGLs to map it.
> 
> Fixes: 955b1b5a00ba ("nvme-pci: move use_sgl initialization to nvme_init_iod()")
> 
> Reported-by: Paul Menzel <pmenzel+linux-nvme at molgen.mpg.de>
> Signed-off-by: Keith Busch <keith.busch at intel.com>
> ---
>   drivers/nvme/host/pci.c | 7 +++++--
>   1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
> index d53550e612bc..a7e94cc3c70e 100644
> --- a/drivers/nvme/host/pci.c
> +++ b/drivers/nvme/host/pci.c
> @@ -451,10 +451,13 @@ static void **nvme_pci_iod_list(struct request *req)
>   static inline bool nvme_pci_use_sgls(struct nvme_dev *dev, struct request *req)
>   {
>   	struct nvme_iod *iod = blk_mq_rq_to_pdu(req);
> +	int nseg = blk_rq_nr_phys_segments(req);
>   	unsigned int avg_seg_size;
>   
> -	avg_seg_size = DIV_ROUND_UP(blk_rq_payload_bytes(req),
> -			blk_rq_nr_phys_segments(req));
> +	if (nseg == 0)
> +		return false;
> +
> +	avg_seg_size = DIV_ROUND_UP(blk_rq_payload_bytes(req), nseg);
>   
>   	if (!(dev->ctrl.sgls & ((1 << 0) | (1 << 1))))
>   		return false;
> 

Thank you for the quick reaction.

Reviewed-by: Paul Menzel <pmenzel+linux-nvme at molgen.mpg.de>


Kind regards,

Paul

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[PATCH] nvme/pci: Check segement valid for SGL use

[Christoph Hellwig]

Thanks, applied.  I'll rebase the changes to take the mapped
scatterlist length on top of this.

[PATCH] nvme/pci: Check segement valid for SGL use

[Christoph Hellwig]

Actually this needs to go into nvme-4.15.  The offending commit is
only in 4.15-rc, and not in nvme-4.16 or Jens' for-4.16 tree.

[PATCH] nvme/pci: Check segement valid for SGL use

[Jens Axboe]

On 1/15/18 9:01 AM, Christoph Hellwig wrote:
> Actually this needs to go into nvme-4.15.  The offending commit is
> only in 4.15-rc, and not in nvme-4.16 or Jens' for-4.16 tree.

I can queue it up for 4.15, there's already been one report of
this...

-- 
Jens Axboe

[PATCH] nvme/pci: Check segement valid for SGL use

[Christoph Hellwig]

On Mon, Jan 15, 2018@09:20:40AM -0700, Jens Axboe wrote:
> On 1/15/18 9:01 AM, Christoph Hellwig wrote:
> > Actually this needs to go into nvme-4.15.  The offending commit is
> > only in 4.15-rc, and not in nvme-4.16 or Jens' for-4.16 tree.
> 
> I can queue it up for 4.15, there's already been one report of
> this...

I think we'll need at least another related fix as well.  I'll
send you a pull request by tomorrow or so.

[PATCH] nvme/pci: Check segement valid for SGL use

[Jens Axboe]

On 1/15/18 10:22 AM, Christoph Hellwig wrote:
> On Mon, Jan 15, 2018@09:20:40AM -0700, Jens Axboe wrote:
>> On 1/15/18 9:01 AM, Christoph Hellwig wrote:
>>> Actually this needs to go into nvme-4.15.  The offending commit is
>>> only in 4.15-rc, and not in nvme-4.16 or Jens' for-4.16 tree.
>>
>> I can queue it up for 4.15, there's already been one report of
>> this...
> 
> I think we'll need at least another related fix as well.  I'll
> send you a pull request by tomorrow or so.

Sounds good, thanks.

-- 
Jens Axboe