[PATCH] nvme-pci: enhance timeout kernel log

[Keith Busch]

On Thu, Dec 07, 2023 at 01:38:04PM -0700, Jens Axboe wrote:
> On 12/7/23 11:32 AM, Keith Busch wrote:
> > From: Keith Busch <kbusch at kernel.org>
> > 
> > Kernel configs don't necessarily have opcode decoding, and some opcodes
> > are not even decodable. It is still interesting for debugging SSD issues
> > to know what opcode is timing out, what request type it came from, and
> > the data size (if applicable).
> > 
> > Signed-off-by: Keith Busch <kbusch at kernel.org>
> > ---
> >  drivers/nvme/host/pci.c | 9 +++++----
> >  1 file changed, 5 insertions(+), 4 deletions(-)
> > 
> > diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
> > index fad4cccce745c..49771919b01f1 100644
> > --- a/drivers/nvme/host/pci.c
> > +++ b/drivers/nvme/host/pci.c
> > @@ -1284,6 +1284,7 @@ static enum blk_eh_timer_return nvme_timeout(struct request *req)
> >  	struct request *abort_req;
> >  	struct nvme_command cmd = { };
> >  	u32 csts = readl(dev->bar + NVME_REG_CSTS);
> > +	u8 opcode;
> >  
> >  	/* If PCI error recovery process is happening, we cannot reset or
> >  	 * the recovery mechanism will surely fail.
> > @@ -1361,11 +1362,11 @@ static enum blk_eh_timer_return nvme_timeout(struct request *req)
> >  	cmd.abort.cid = nvme_cid(req);
> >  	cmd.abort.sqid = cpu_to_le16(nvmeq->qid);
> >  
> > +	opcode = nvme_req(req)->cmd->common.opcode,
> >  	dev_warn(nvmeq->dev->ctrl.device,
> > -		"I/O %d (%s) QID %d timeout, aborting\n",
> > -		 req->tag,
> > -		 nvme_get_opcode_str(nvme_req(req)->cmd->common.opcode),
> > -		 nvmeq->qid);
> > +		 "I/O %d (%s %d) QID %d timeout, aborting req_op:%u size:%u\n",
> > +		 req->tag, nvme_get_opcode_str(opcode), opcode, nvmeq->qid,
> > +		 req_op(req), blk_rq_bytes(req));
> 
> Your additions look good to me, but I do wish that we'd be equally
> verbose on what the other values are. Ala:
> 
> 	I/O tag %d (opcode: %s %d) ...
> 
> would be a lot more useful, for example. I find myself having to dig
> into the source for a specific kernel sometimes when looking at various
> nvme errors, which is really annoying.

That is annoying. I'll add your suggestion in.