Re: [PATCH v2 06/17] IB/core: Add support for extended query device caps

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

Hi Roland,

Le mardi 09 décembre 2014 à 13:43 -0800, Roland Dreier a écrit :
> I was getting ready to apply the ODP series, but then I noticed:
> 
> On Tue, Nov 11, 2014 at 8:36 AM, Haggai Eran <haggaie-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org> wrote:
> > diff --git a/drivers/infiniband/core/uverbs_main.c b/drivers/infiniband/core/uverbs_main.c
> > index 71ab83fde472..974025028790 100644
> > --- a/drivers/infiniband/core/uverbs_main.c
> > +++ b/drivers/infiniband/core/uverbs_main.c
> > @@ -122,7 +122,8 @@ static int (*uverbs_ex_cmd_table[])(struct ib_uverbs_file *file,
> >                                     struct ib_udata *ucore,
> >                                     struct ib_udata *uhw) = {
> >         [IB_USER_VERBS_EX_CMD_CREATE_FLOW]      = ib_uverbs_ex_create_flow,
> > -       [IB_USER_VERBS_EX_CMD_DESTROY_FLOW]     = ib_uverbs_ex_destroy_flow
> > +       [IB_USER_VERBS_EX_CMD_DESTROY_FLOW]     = ib_uverbs_ex_destroy_flow,
> > +       [IB_USER_VERBS_EX_CMD_QUERY_DEVICE]     = ib_uverbs_ex_query_device
> >  };
> >
> >  static void ib_uverbs_add_one(struct ib_device *device);
> 
> > diff --git a/include/uapi/rdma/ib_user_verbs.h b/include/uapi/rdma/ib_user_verbs.h
> > index 26daf55ff76e..ed8c3d9da42c 100644
> > --- a/include/uapi/rdma/ib_user_verbs.h
> > +++ b/include/uapi/rdma/ib_user_verbs.h
> > @@ -90,8 +90,9 @@ enum {
> >  };
> >
> >  enum {
> > +       IB_USER_VERBS_EX_CMD_QUERY_DEVICE = IB_USER_VERBS_CMD_QUERY_DEVICE,
> >         IB_USER_VERBS_EX_CMD_CREATE_FLOW = IB_USER_VERBS_CMD_THRESHOLD,
> > -       IB_USER_VERBS_EX_CMD_DESTROY_FLOW
> > +       IB_USER_VERBS_EX_CMD_DESTROY_FLOW,
> >  };
> 
> And this makes no sense to me.  I thought the whole point of "EX"
> commands was to add then after IB_USER_VERBS_CMD_THRESHOLD.
> 
> In this case, if you make IB_USER_VERBS_EX_CMD_QUERY_DEVICE =
> IB_USER_VERBS_CMD_QUERY_DEVICE then doesn't the entry in
> uverbs_cmd_table[] for normal query device get overwritten with
> ib_uverbs_ex_query_device()??
> 

IB_USER_VERBS_CMD_THRESHOLD was introduced as part of commit
400dbc96583f ('IB/core: Infrastructure for extensible uverbs commands').

When I've 'upgraded' it to more extensible scheme, in commit
f21519b23c1b ('IB/core: extended command: an improved infrastructure 
for uverbs commands'), I've put the extended commands in a different 
namespace, with the idea we could later convert non-extended commands 
to extended ones and phase out the older ABI in the future.

I seems that what I've envisioned is starting to happen.

Regards.

-- 
Yann Droneaud
OPTEYA


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