Re: [PATCH] RDMA/efa: Fix node guid compiler warning

["Margolin, Michael" <mrgolin@amazon.com>]

On 9/26/2024 3:56 PM, Margolin, Michael wrote:
> On 9/24/2024 9:00 PM, Jason Gunthorpe wrote:
>
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>>
>>
>> On Tue, Sep 24, 2024 at 12:16:03PM +0000, Michael Margolin wrote:
>>> The GUID is received in big-endian so align types accordingly to avoid
>>> compiler warnings.
>>>
>>> Closes: 
>>> https://lore.kernel.org/oe-kbuild-all/202409032113.bvyVfsNp-lkp@intel.com/
>>>
>>> Fixes: 04e36fd27a2a ("RDMA/efa: Add support for node guid")
>>> Reported-by: kernel test robot <lkp@intel.com>
>>> Reviewed-by: Yehuda Yitschak <yehuday@amazon.com>
>>> Reviewed-by: Yonatan Nachum <ynachum@amazon.com>
>>> Signed-off-by: Michael Margolin <mrgolin@amazon.com>
>>> ---
>>>   drivers/infiniband/hw/efa/efa_com_cmd.c | 2 +-
>>>   drivers/infiniband/hw/efa/efa_com_cmd.h | 2 +-
>>>   2 files changed, 2 insertions(+), 2 deletions(-)
>>>
>>> diff --git a/drivers/infiniband/hw/efa/efa_com_cmd.c 
>>> b/drivers/infiniband/hw/efa/efa_com_cmd.c
>>> index 5a774925cdea..5754da4e6ff8 100644
>>> --- a/drivers/infiniband/hw/efa/efa_com_cmd.c
>>> +++ b/drivers/infiniband/hw/efa/efa_com_cmd.c
>>> @@ -465,7 +465,7 @@ int efa_com_get_device_attr(struct efa_com_dev 
>>> *edev,
>>>        result->db_bar = resp.u.device_attr.db_bar;
>>>        result->max_rdma_size = resp.u.device_attr.max_rdma_size;
>>>        result->device_caps = resp.u.device_attr.device_caps;
>>> -     result->guid = resp.u.device_attr.guid;
>>> +     result->guid = (__force __be64)resp.u.device_attr.guid;
>> That can't be right, use the proper conversion function, or the proper
>> type..
>>
>> Jason
> The current assumption in the driver is that data from the device 
> arrives in a correct byte order for the CPU, while the guid field is 
> in reversed order.
>
> Would you suggest doing something like:
>
>> -     result->guid = resp.u.device_attr.guid;
>> +     result->guid = __cpu_to_be64(__swab64(resp.u.device_attr.guid));
>
> Michael
>
Actually that's wrong, the device always sets guid in BE order so no 
swap is needed in the driver in any case.