From mboxrd@z Thu Jan 1 00:00:00 1970 From: Leon Romanovsky Subject: Re: [RFC PATCH] RDMA/cma: Remove netlink interface of CMA statistics Date: Tue, 21 Nov 2017 07:53:08 +0200 Message-ID: <20171121055308.GN18825@mtr-leonro.local> References: <20171114095605.GU18825@mtr-leonro.local> <20171114173516.GZ18825@mtr-leonro.local> <20171115052926.GN18825@mtr-leonro.local> <20171120194152.GN29075@ziepe.ca> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="Xr0h8fiiTMtsWkNx" Return-path: Content-Disposition: inline In-Reply-To: Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Or Gerlitz Cc: Jason Gunthorpe , Doug Ledford , Sean Hefty , Hal Rosenstock , "linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , Parav Pandit , Moni Shoua List-Id: linux-rdma@vger.kernel.org --Xr0h8fiiTMtsWkNx Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Tue, Nov 21, 2017 at 12:14:01AM +0200, Or Gerlitz wrote: > On Mon, Nov 20, 2017 at 9:41 PM, Jason Gunthorpe wrote: > > > Well, I would like to know the issues as well, as I've already said I > > think they should be described in the commit message. > > > But also, at the RFC stage the onus is on other people, particularly > > people that want to keep the feature, to explain where it is being > > used and why.. > > we did it to allow user space track rdma-cm connections through the rdma > subsystem netlink infra-structure, e.g one can come up with netstat like > reporting of rdma listeners and connections, this is it! And after 7 years did anyone use it? The answer is no and it is because this interface was added without any real user space application which was supposed to use it. > > > We need to decide if we drop the RFC and fix the implementation, apply > > the the RFC, or add a deprecation printk warning, or something.. > > right. To my opinion, if there are issues in the implementation, lets fix them, > I don't see why remove this implementation and replace it with a new one > that does the same thing. Just looking at the code without deep dive. 1. Lack of extensibility, in case of desire to add new field to rdma_cm_id_stats, you will need to throw away this struct and add new netlink attribute. 2. Device list lock for data retrieval - user can prevent device from recovery (maybe). 3. It doesn't return device ID !!!!! 4. Completely unscalable by sending message per-struct and not using netlink nested tables. 5. No check of device identifiers -> returns everything. 4. There is no nlmsg_end at the end of message. Are you going to fix it? > > > Please try to be productive here and concentrate on adding information > > and not nit-picking the process! We all know removing a uapi is a big > > deal. > > Re usage I provided what I know. It is wishful thinking, I'm interested in real users and real applications. Do you know about such? Thanks --Xr0h8fiiTMtsWkNx Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEkhr/r4Op1/04yqaB5GN7iDZyWKcFAloTv0QACgkQ5GN7iDZy WKf//Q//bS49teIfFHJ74u+zLrb+hiqPURpj+SJVJ1vQMfN3FrPf9ZxozDHQFk1p zHl1DGZmiVh/RfzLxuTxJ4IT3Zzx7H20f7P0jlUmCn7YmDInOcnVRHJICzbEs7o6 F9YuCsNqm25fr92GcJzoNgpHyjFDZKJadSlVhDhdCWoT2t4yqT/kh0/zwVBkHlTr plQnD2806ReSGQOzH61C7y+w0OHlVZenWo9j+ZOswsO0D4q+hubuzgizoXImdwia argv1TzgKnnsFAuf/u/iB+cElXg96BjgrW05wnokHV3mYNuZ6HuULS7nc9bz9cN6 dZ+cQiVTUtDZu2fTgGuUbg2JrhKabtqt+EttxPPKsnj/7pUOWPMJpbiWbUH4moqd H6coYnv30Z5Y+xS+Lk21PTkvukEcz0xRA2x/8pmMcPcSNo3xfFcTcbTjHi064a0e VrS1yfxSABU+BAc05nqr+cQ5fnD6PJe/Gn4gCavCr/yQRxoISdhKckmyhf1RMOx/ Dl4O8G924C8zHc1dMeHTsyKP73dssH7uRwUrXnvs2gKC+bR3AN554zJRCnBjroQ3 Pm5SyHRY8LGFdYb0WJeFUMxyamPgjOtjsilk89e+x76EUPVRPjVdb4h2MsUbppzO b5nfiVIT3qsCZqW5fYgnL8q2GWe1Jgw03liri+2mLaGh5V1dN7E= =+N3G -----END PGP SIGNATURE----- --Xr0h8fiiTMtsWkNx-- -- To unsubscribe from this list: send the line "unsubscribe linux-rdma" in the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org More majordomo info at http://vger.kernel.org/majordomo-info.html