Re: [PATCHv2 RFC] IB: Add rdma_cap_ib_switch helper and use where appropriate

[Hal Rosenstock <hal-LDSdmyG8hGV8YrgS2mwiifqBs+8SCbDb@public.gmane.org>]

On 6/22/2015 4:20 PM, Jason Gunthorpe wrote:
> On Thu, Jun 18, 2015 at 07:25:32PM -0400, Hal Rosenstock wrote:
>> Persuant to Liran's comments on node_type on linux-rdma
>> mailing list:
>>
>> In an effort to reform the RDMA core and ULPs to minimize use of
>> node_type in struct ib_device, an additional bit is added to
>> struct ib_device for is_switch (IB switch). This is needed 
>> to be initialized by any IB switch device driver. This is a 
>> NEW requirement on such device drivers which are all
>> "out of tree".
>>
>> In addition, an ib_switch helper was added to ib_verbs.h
>> based on the is_switch device bit rather than node_type
>> (although those should be consistent).
>>
>> The RDMA core (MAD, SMI, agent, sa_query, multicast, sysfs)
>> as well as (IPoIB and SRP) ULPs are updated where
>> appropriate to use this new helper. In some cases,
>> the helper is now used under the covers of using
>> rdma_[start end]_port rather than the open coding
>> previously used.
>>
>> Signed-off-by: Hal Rosenstock <hal-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
> 
> Looks pretty good now.
> 
> Reviewed-By: Jason Gunthorpe <jgunthorpe-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
> 
> Although a bitfield isn't my preference:
> 
>> index 986fddb..b0f898e 100644
>> +++ b/include/rdma/ib_verbs.h
>> @@ -1745,6 +1745,7 @@ struct ib_device {
>>  	char			     node_desc[64];
>>  	__be64			     node_guid;
>>  	u32			     local_dma_lkey;
>> +	u16                          is_switch:1;
>>  	u8                           node_type;
>>  	u8                           phys_port_cnt;

What would be better/what would be your preference ?

Note that there still remain a couple of node type checks in the kernel
that we may want to remove. There's an IB CA check in cma.c:rdma_notify
as well as in rds/ib.c:rds_ib_add_one and rds_ib_laddr_check and an RNIC
check in rds/iw.c:rds_iw_add_one and rds_iw_laddr_check. Should these be
changed not to use node type ?

-- Hal

> Jason
> 

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