Re: [PATCH for-next 1/2] RDMA/efa: Move host info set to first ucontext allocation

[Gal Pressman <galpress@amazon.com>]

On 05/01/2021 13:21, Leon Romanovsky wrote:
> On Tue, Jan 05, 2021 at 12:43:25PM +0200, Gal Pressman wrote:
>> Downstream patch will require the userspace version which is passed as
>> part of ucontext allocation. Move the host info set there and make sure
>> it's only called once (on the first allocation).
>>
>> Reviewed-by: Firas JahJah <firasj@amazon.com>
>> Reviewed-by: Leonid Feschuk <lfesch@amazon.com>
>> Signed-off-by: Gal Pressman <galpress@amazon.com>
>> ---
>>  drivers/infiniband/hw/efa/efa.h       | 7 +++++++
>>  drivers/infiniband/hw/efa/efa_main.c  | 4 +---
>>  drivers/infiniband/hw/efa/efa_verbs.c | 3 +++
>>  3 files changed, 11 insertions(+), 3 deletions(-)
>>
>> diff --git a/drivers/infiniband/hw/efa/efa.h b/drivers/infiniband/hw/efa/efa.h
>> index e5d9712e98c4..9c9cd5867489 100644
>> --- a/drivers/infiniband/hw/efa/efa.h
>> +++ b/drivers/infiniband/hw/efa/efa.h
>> @@ -45,6 +45,11 @@ struct efa_stats {
>>       atomic64_t keep_alive_rcvd;
>>  };
>>
>> +enum {
>> +     EFA_FLAGS_HOST_INFO_SET_BIT,
>> +     EFA_FLAGS_NUM,
>> +};
>> +
>>  struct efa_dev {
>>       struct ib_device ibdev;
>>       struct efa_com_dev edev;
>> @@ -62,6 +67,7 @@ struct efa_dev {
>>       struct efa_irq admin_irq;
>>
>>       struct efa_stats stats;
>> +     DECLARE_BITMAP(flags, EFA_FLAGS_NUM);
>>  };
> 
> Why do you need such over-engineering?
> What is wrong with old school "u8 flag"?

The main reason is for the atomic test_and_set_bit() usage, otherwise it would
be an atomic flag, not u8 flag.