Re: [PATCH v1 1/5] IB/uverbs: ex_query_device: answer must not depend on request's comp_mask

[Yann Droneaud <ydroneaud-RlY5vtjFyJ3QT0dZR+AlfA@public.gmane.org>]

Hi,

Le jeudi 29 janvier 2015 à 15:17 -0800, Roland Dreier a écrit :
> On Thu, Jan 29, 2015 at 1:59 PM, Yann Droneaud <ydroneaud-RlY5vtjFyJ3QT0dZR+AlfA@public.gmane.org> wrote:
> >> Roland: I agree with Yann, these patches need to go in, or the ODP
> >> patches reverted.
> 
> > Reverting all On Demand Paging patches seems overkill:
> > if something as to be reverted it should be commit 5a77abf9a97a
> > ("IB/core: Add support for extended query device caps") and the part of
> > commit 860f10a799c8 ("IB/core: Add flags for on demand paging support")
> > which modify ib_uverbs_ex_query_device().
> 
> Thank you and Jason for taking on this interface.
> 
> At this point I feel like I do about the IPoIB changes -- we should
> revert the broken stuff and get it right for 3.20.
> 
> If we revert the two things you describe above, is everything else OK
> to leave in 3.19 with respect to ABI?
> 

I've tried to review every changes since v3.18 on drivers/infiniband
include/rdma and include/uapi/rdma with respect to ABI issues.

I've noticed no other issue, but I have to admit I've not well reviewed
the drivers (hw/) internal changes.

If the IB_USER_VERBS_EX_CMD_QUERY_DEVICE and ib_uverbs_ex_query_device
changes are going to be reverted for v3.19, the on-demand-paging
feature will be available (IB_DEVICE_ON_DEMAND_PAGING will be set 
device_cap_flags in response to non extended QUERY_DEVICE for mlx5 HCA
and IB_ACCESS_ON_DEMAND access flag will be effective for REG_MR 
uverbs), but its parameters won't be. I don't know if it's a no-go for 
the usage of on-demand paging by userspace: I have not the chance
of owning HCA with the support for this feature, nor the patches
libibverbs / libmlx5 ... (anyway I would not have the time to test).
I've hoped people from Mellanox would have commented on the revert 
option too.

Regards.

-- 
Yann Droneaud
OPTEYA