Re: [RFC ABI V2 8/8] RDMA/mlx5: Add mlx5 initial support of the new infrastructure

From: Jason Gunthorpe <jgunthorpe-ePGOBjL8dl3ta4EC/59zMFaTQe2KTcn/@public.gmane.org>
To: Matan Barak <matanb-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
Cc: linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org,
	Doug Ledford <dledford-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org>,
	Sean Hefty <sean.hefty-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org>,
	Liran Liss <liranl-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>,
	Haggai Eran <haggaie-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>,
	Tal Alon <talal-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>,
	Majd Dibbiny <majd-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>,
	Christoph Lameter <cl-vYTEC60ixJUAvxtiuMwx3w@public.gmane.org>,
	Leon Romanovsky <leonro-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>
Subject: Re: [RFC ABI V2 8/8] RDMA/mlx5: Add mlx5 initial support of the new infrastructure
Date: Thu, 21 Jul 2016 10:49:52 -0600	[thread overview]
Message-ID: <20160721164952.GE19849@obsidianresearch.com> (raw)
In-Reply-To: <8ffd0f92-2564-cc39-10ab-5db287399e82-VPRAkNaXOzVWk0Htik3J/w@public.gmane.org>

On Thu, Jul 21, 2016 at 02:38:28PM +0300, Matan Barak wrote:
> On 20/07/2016 20:39, Jason Gunthorpe wrote:
> >On Tue, Jul 19, 2016 at 06:23:32PM +0300, Matan Barak wrote:
> >>+DECLARE_UVERBS_TYPE(
> >>+	mlx5_device,
> >>+	UVERBS_CTX_ACTION(
> >>+		DEVICE_ALLOC_CONTEXT, uverbs_get_context, NULL,
> >>+		&uverbs_get_context_spec,
> >>+		&UVERBS_ATTR_CHAIN_SPEC(
> >>+			/*
> >>+			 * Declared with size 0 as we current provide
> >>+			 * backward compatibility (0 = variable size)
> >>+			 */
> >>+			UVERBS_ATTR_PTR_IN(ALLOC_UCONTEXT_IN, 0),
> >>+			UVERBS_ATTR_PTR_OUT(ALLOC_UCONTEXT_OUT, 0),
> >>+			),
> >>+	),
> >>+	UVERBS_ACTION(
> >>+		DEVICE_QUERY, uverbs_query_device_handler, NULL,
> >>+		&uverbs_query_device_spec,
> >>+	),
> >>+);
> >
> >The entire point of getting rid of the lists and changing the destruct
> >ordering was to avoid the need to have this kind of stuff in the
> >drivers.
> >
> >I really don't want to see driver changes to implement the basic
> >API..
> >
> 
> You could declare entire types in a common space (and these two examples
> qualify for common declarations). However, if one wants to add driver
> specific arguments for  this command (besides some general arguments which
> could be driver dependent), it needs to be in a driver specific files.
> 
> I think this is a good trade-off between driver specific arguments, commands
> and types while sharing common handlers and command descriptors.

Are you going to fix and test every driver in the kernel?

In the interests of sanity, I think you need to provide a
straightforward way to retain the status-quo udata, at least as an
interm step..

I'm not excited to see things start here..

Jason
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