linux-kernel - Re: [PATCH 2/2] IB/core: Set width to 1X for invalid active widths when port is down

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Date:   Fri, 16 Mar 2018 10:38:54 +0800
From:   Honggang LI <honli@...hat.com>
To:     Hal Rosenstock <hal@....mellanox.co.il>
Cc:     dledford@...hat.com, jgg@...pe.ca, linux-rdma@...r.kernel.org,
        noaos@...lanox.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2/2] IB/core: Set width to 1X for invalid active widths
 when port is down

On Thu, Mar 15, 2018 at 08:47:44AM -0400, Hal Rosenstock wrote:
> On 3/15/2018 8:43 AM, Honggang LI wrote:
> > On Thu, Mar 15, 2018 at 08:32:02AM -0400, Hal Rosenstock wrote:
> >> On 3/15/2018 8:01 AM, Hal Rosenstock wrote:
> >>> On 3/15/2018 5:02 AM, Honggang LI wrote:
> >>>> From: Honggang Li <honli@...hat.com>
> >>>>
> >>>> commit f1b65df5a232 ("IB/mlx5: Add support for active_width and
> >>>> active_speed in RoCE"). Before this patch applied, the mlx5_ib
> >>>> driver set default active_width and active_speed to IB_WIDTH_4X
> >>>> and IB_SPEED_QDR.
> >>>>
> >>>> When the RoCE port is down, the RoCE port did not negotiate the
> >>>> active width with remote side. The active width is zero. If run
> >>>> ibstat to require the port status, ibstat will panic as it read
> >>>> invalid width from sys file.
> >>>>
> >>>> Signed-off-by: Honggang Li <honli@...hat.com>
> >>>> ---
> >>>>  drivers/infiniband/core/sysfs.c | 15 +++++++++++----
> >>>>  1 file changed, 11 insertions(+), 4 deletions(-)
> >>>>
> >>>> diff --git a/drivers/infiniband/core/sysfs.c b/drivers/infiniband/core/sysfs.c
> >>>> index cf36ff1f0068..722e4571f4d2 100644
> >>>> --- a/drivers/infiniband/core/sysfs.c
> >>>> +++ b/drivers/infiniband/core/sysfs.c
> >>>> @@ -240,6 +240,7 @@ static ssize_t rate_show(struct ib_port *p, struct port_attribute *unused,
> >>>>  	struct ib_port_attr attr;
> >>>>  	char *speed = "";
> >>>>  	int rate;		/* in deci-Gb/sec */
> >>>> +	int width;
> >>>>  	ssize_t ret;
> >>>>  
> >>>>  	ret = ib_query_port(p->ibdev, p->port_num, &attr);
> >>>> @@ -278,13 +279,19 @@ static ssize_t rate_show(struct ib_port *p, struct port_attribute *unused,
> >>>>  		break;
> >>>>  	}
> >>>>  
> >>>> -	rate *= ib_width_enum_to_int(attr.active_width);
> >>>> -	if (rate < 0)
> >>>> -		return -EINVAL;
> >>>> +	width = ib_width_enum_to_int(attr.active_width);
> >>>> +	if (width < 0) {
> >>>> +		if (attr.state != IB_PORT_ACTIVE)
> >>>
> >>> Link width is valid in any PortState other than Down so I think that
> >>> this check should be:
> >>> 		if (attr.state != IB_PORT_DOWN)
> >>>
> >>> However, I don't think overriding width should be needed for this case
> >>> and just returning -EINVAL should be fine regardless of port state.
> >>> AFAIK it's the driver responsibility to populate acceptable defaults for
> >>> such parameters. What driver(s) have this issue ? Shouldn't it be fixed
> >>> there rather than here ?
> >>
> >> I just noticed that you reference commit f1b65df5a232 ("IB/mlx5: Add
> >> support for active_width and active_speed in RoCE"). Before this patch
> >> applied, the mlx5_ib driver set default active_width and active_speed to
> >> IB_WIDTH_4X and IB_SPEED_QDR.
> >>
> >> Should the fix be to hw/mlx5/main.c:translate_eth_proto_oper which now has:
> >>
> >>         switch (eth_proto_oper) {
> >> ...
> >>         default:
> >>                 return -EINVAL;
> >>         }
> >>
> >>         return 0;
> >>
> >> and change default case to:
> >> 		*active_width = IB_WIDTH_1X;
> >>
> >> ?
> > 
> > I suggest to restore previous behavior before apply f1b65df5a232.
> > 
> > diff --git a/drivers/infiniband/hw/mlx5/main.c b/drivers/infiniband/hw/mlx5/main.c
> > index 033b6af90de9..0d73d2772d9b 100644
> > --- a/drivers/infiniband/hw/mlx5/main.c
> > +++ b/drivers/infiniband/hw/mlx5/main.c
> > @@ -388,6 +388,9 @@ static int mlx5_query_port_roce(struct ib_device *device, u8 port_num,
> >  	if (err)
> >  		goto out;
> >  
> > +        props->active_width     = IB_WIDTH_4X;
> > +        props->active_speed     = IB_SPEED_QDR;
> > +
> >  	translate_eth_proto_oper(eth_prot_oper, &props->active_speed,
> >  				 &props->active_width);
> >  
> 
> Sure; makes sense that it should preserve the original behavior for this
> case.

[PATCH] IB/mlx5: Set the default active rate and width to QDR and 4X

This new patch had been sent to upstream mailing list for review.

thanks