On 3/15/2018 8:01 AM, Hal Rosenstock wrote:
> On 3/15/2018 5:02 AM, Honggang LI wrote:
>> From: Honggang Li <ho...@redhat.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 <ho...@redhat.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;

?

> -- Hal
> 
>> +                    width = 1; /* default to 1X for invalid widths */
>> +            else
>> +                    return -EINVAL;
>> +    }
>> +
>> +    rate *= width;
>>  
>>      return sprintf(buf, "%d%s Gb/sec (%dX%s)\n",
>>                     rate / 10, rate % 10 ? ".5" : "",
>> -                   ib_width_enum_to_int(attr.active_width), speed);
>> +                   width, speed);
>>  }
>>  
>>  static ssize_t phys_state_show(struct ib_port *p, struct port_attribute 
>> *unused,
>>

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