From mboxrd@z Thu Jan 1 00:00:00 1970 From: Leon Romanovsky Subject: Re: [PATCH rdma-next] Revert "IB/core: Add flow control to the portmapper netlink calls" Date: Sun, 4 Jun 2017 08:36:35 +0300 Message-ID: <20170604053635.GD6868@mtr-leonro.local> References: <20170529082423.1180-1-leon@kernel.org> <20170530212431.GA21008@ssaleem-MOBL4.amr.corp.intel.com> <20170531040437.GE5406@mtr-leonro.local> <20170531174245.GA16304@ssaleem-MOBL4.amr.corp.intel.com> <1496261429.2608.15.camel@sandisk.com> <20170602162849.GA28660@ssaleem-MOBL4.amr.corp.intel.com> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="0lnxQi9hkpPO77W3" Return-path: Content-Disposition: inline In-Reply-To: <20170602162849.GA28660-GOXS9JX10wfOxmVO0tvppfooFf0ArEBIu+b9c/7xato@public.gmane.org> Sender: linux-rdma-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Shiraz Saleem Cc: Bart Van Assche , "Latif, Faisal" , "leonro-Nfu5REtnQAJWk0Htik3J/w@public.gmane.org" , "Ismail, Mustafa" , "linux-rdma-u79uwXL29TY76Z2rM5mHXA@public.gmane.org" , "dledford-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org" , "swise-7bPotxP6k4+P2YhJcF5u+vpXobYPEAuW@public.gmane.org" List-Id: linux-rdma@vger.kernel.org --0lnxQi9hkpPO77W3 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Fri, Jun 02, 2017 at 11:28:49AM -0500, Shiraz Saleem wrote: > On Wed, May 31, 2017 at 02:10:31PM -0600, Bart Van Assche wrote: > > On Wed, 2017-05-31 at 12:42 -0500, Shiraz Saleem wrote: > > > > 5. I proposed a solution -> go and fix your user space program. > > > > > > This is a kernel patch you are trying to revert, you are breaking existing > > > kernel functionality. Nothing to do with user space. > > > > > > Bottom line, come up with a solution that will address both port mapper > > > functionality and your issue. > > > > Hello Shiraz, > > > > Sorry that this means additional work for you, but I agree with Leon that > > user space software should not assume that netlink sockets are a reliable > > communication mechanism. > > Hi Bart - Thank you for your response. > > The original problem was that ibnl_unicast, which is used to send nl messages from > portmapper kernel space to user-space, would occasionally and momentarily fail under stress. > We could have retried the call for a certain amount of time, but since netlink_unicast has a > nonblock/block parameter, we chose to use the blocking option with a timeout. So we thought we > did account for deadlocks with this timeout. Not really, you just reduced the chances. In very large scale, you will have a very large chances of such deadlocks. Thanks > > > -- > 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 --0lnxQi9hkpPO77W3 Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEkhr/r4Op1/04yqaB5GN7iDZyWKcFAlkznGMACgkQ5GN7iDZy WKczGA//Xdk7Vgpt1rpc1fX4F/hbikKYevHIJGm2SlFsrcf60IGye/kIpV4OAkLs kpxqtgKoJxIE/6ukAIy2ZIchKBQ28HdWrEKIoMZCllveRsn2QmvAnhkLhPHWVJVG JPdT5DUefFlXyR4oAXt6JszBm7QulCp/1qZKq0ZP9EoK1sKlqjOjhGFup5V/3kP4 OFHOstlrPUp8G0gkHlj6M7yNkUP/rc6AZ3apGPjDyKII3y3XOjZ2WTrD2IphARaM YWpZfpxAsuxFCv023pjtwZvwF25hO7gfJc4n9Pk17rCkTr07mb+5ssVMVA5LzrGA mAI/noD8PKfgb+3IfYY92tVpe9ZGQyY9nIFTM2/iz77ByEuojtWcFEtIcvCzo7v3 umYdkFJE1258zZ5H2qSU10E7bsGuccGoaiaT3fcBYjGa9iZDWh8Nz2SyX2daEvBn iWi+sGbP0dEdSPNRK6SoFsH/FxR3l4oWQsvNb1vwf8IT8gXrz+KPmgj4KXSj4MFt 4DAbG0cZXOmkFyvjjI6RE6YZTBceadCnlP5u5OrJQEh4rMSIf+QzYKCwX6z3z3LO FjcCsL3aoZiD25znWISH3ci2/bpT/i1fi39OQBvMjN5ADsDV2EtrPoVEfGbyKu6w y+mOdVgxBylWzKUUA/9ufoNKNq6/l4AVhQRmNJglbqTIobszw2o= =YjcV -----END PGP SIGNATURE----- --0lnxQi9hkpPO77W3-- -- 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