From mboxrd@z Thu Jan 1 00:00:00 1970 From: Leon Romanovsky Subject: Re: [PATCH rdma v1 1/1] IB/core: Fix input len in multiple user verbs Date: Fri, 18 Aug 2017 18:58:08 +0300 Message-ID: <20170818155808.GN23648@mtr-leonro.local> References: <1498572282-22370-1-git-send-email-Ram.Amrani@cavium.com> <1498572282-22370-2-git-send-email-Ram.Amrani@cavium.com> <20170628095422.GA1248@mtr-leonro.local> <20170628101124.GD1248@mtr-leonro.local> <1503068404.2598.9.camel@redhat.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="Ms5iOKSBOB9YS8zC" Return-path: Content-Disposition: inline In-Reply-To: <1503068404.2598.9.camel-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Doug Ledford Cc: "Elior, Ariel" , "Amrani, Ram" , "linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" List-Id: linux-rdma@vger.kernel.org --Ms5iOKSBOB9YS8zC Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Fri, Aug 18, 2017 at 11:00:04AM -0400, Doug Ledford wrote: > On Wed, 2017-06-28 at 10:23 +0000, Elior, Ariel wrote: > > > From: Leon Romanovsky [mailto:leon-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org] > > > Sent: Wednesday, June 28, 2017 1:11 PM > > > To: Amrani, Ram > > > Cc: dledford-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org; linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org; Elior, Ariel > > > > > > Subject: Re: [PATCH rdma v1 1/1] IB/core: Fix input len in multiple > > > user verbs > > > > > > On Wed, Jun 28, 2017 at 10:02:45AM +0000, Amrani, Ram wrote: > > > > > > Most user verbs pass user data to the kernel with the > > > > > > inclusion of the > > > > > > ib_uverbs_cmd_hdr structure. This is problematic because the > > > > > > vendor has > > > > > > no ideas if the verb was called by a legacy verb or an > > > > > > extended verb. > > > > > > > > > > Why vendor should know about it? It has midlayer (ib/core) > > > > > between him > > > > > and user to handle it. > > > > > > > > > > > > > Knowing the inlen can be used to determine if the library is > > > > newer than > > > > the kernel and what features it supports or not. > > > > > > It is not interesting case, because we are not breaking UAPI, only > > > extending. It ensures that kernel will fill as much as possible and > > > will > > > always have success in it. After that it is library responsibility > > > to > > > understand if everything was filled. > > > > > > Thanks > > > > In our case, kernel driver needs to know whether library supports a > > certain > > feature (doorbell overflow recovery). It doesn't care if it was an > > extended > > verb or not, but it cares whether the lib is sufficiently new to have > > provided > > the required information. If the library is sufficiently new > > (supports) then > > kernel will register the library's doorbell address with the overflow > > recovery > > mechanism, and perform recovery if required, otherwise it would not > > (as the > > library is not supplying the necessary information for recovery to > > take place). > > This is not something the library needs to know, but the kernel > > driver. Having > > correct input len is required for successfully avoiding breaking the > > UAPI. > > Leon, does this explanation resolve your objections? Also, have you > checked the mlx5/mthca portions of this patch? Yes, let's me recheck/rerun the patch and post results. If for any reasons you don't hear from me till Wednesday, take it. Thanks > > -- > Doug Ledford > GPG KeyID: B826A3330E572FDD > Key fingerprint = AE6B 1BDA 122B 23B4 265B 1274 B826 A333 0E57 2FDD > --Ms5iOKSBOB9YS8zC Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEkhr/r4Op1/04yqaB5GN7iDZyWKcFAlmXDpAACgkQ5GN7iDZy WKe4Sw//TYSc5+t1YMLqeEAbjTRvQuZ1p+m89/YE8O/FgWJ4zXAHB0aM8Or01gow wYEop/5DR+9Y6idxn+i3geQjFVrSfjbDv1/wOxrJ03iSb9ZZCod+abNpQt9DsbAu UZbG5lwhW+vXDTW1hSR9QMI9ncBLrNMft4YFZd4lT6WgvatWiesHLdeCc5yzariR 0eVrlbVsETqiojbpTYGmGHxRzJMfhx+3faS6GBGv0f3AE5Gon2X9IYtmLWJxBSXP /mbgE/p6K5+tpn4Dh2ABxDqViIGHvs/E74uhmN+pRuUkJrI/jDT5LmDYeTqshxn+ qvsBFddyaWOaPy0huN3Qehtp3mq2Q/DVEbGX90ALbkrPJjC8w8n31zWXd9XCYZIG 3ju2ig0+H0H604So0z+xC2fJMFiTRb90Gs7rNCrGxKb4reEnQritAG/o1BuXnOJu J7jBLpgpb/NJXX1XiK2Nc2rQplead1s/5CvgJxGwe8isN+kjs9B2M5hQAZOVi8oM muSBDNLjtsil7OqdWgVrO5vHmnnwHInH3GFSV4KQfVKIfdek+jRBGCmdUeSQu/+v Z22LlRv7DH6grhObT5neq2LTh5Zi5swbqsOGIi6BKjvvdDpCYT7WcgyVlgWiXN5J f2dLV1vXnMzbVy0Ho5Ejd9FjqIlaEdD59UPzSp5hfe2ym36Jgfg= =W6yX -----END PGP SIGNATURE----- --Ms5iOKSBOB9YS8zC-- -- 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