[Users] RDMA issues in ib_qib [was:IPoIB on CentOS 6.5]

[Foraker, Jim]

On 3/23/15, 2:24 AM, "Peter Kjellström" <cap at nsc.liu.se> wrote:

>On Thu, 19 Mar 2015 16:17:09 +0000
>"Foraker, Jim" <foraker1 at llnl.gov> wrote:
>
>> Peter,
>>      Thanks.  I¹ve told our RedHat folks that the IPoIB issue is a
>> high priority for us.  Our bug for the qib kernel RDMA issue is
>> 1188417, which was closed as a duplicate of
>> https://bugzilla.redhat.com/show_bug.cgi?id=1171803.
>
>And (no surprise) both those are non-public. Can you give a short
>summary (root cause, work-around, fix planned for, ..)?
     Sorry, I prodded one of our RH folks to make our BZ public again.  It
should be visible now.  In case it¹s not, the problem boils down to to a
snippet of qib_mag_sg() in qib_dma.c:

#ifdef CONFIG_NEED_SG_DMA_LENGTH
		sg->dma_length = sg->length
#endif

     CONFIG_NEED_SG_DMA_LENGTH is a config option from more recent kernels
not present in RHEL6.  It appears to have been inadvertently brought in
while backporting an upstream patch.  (struct scatterlist).dma_length
should be getting set in RHEL6, but because of the ifdef, it¹s not.
Remove the ifdef and kernel RDMA works fine again.

     Jim  

>
>Tia,
> Peter
> 
>>      Jim
>