From mboxrd@z Thu Jan 1 00:00:00 1970 From: Louis Rilling Subject: Re: [PATCH 2/6] c/r: [pty 1/2] allow allocation of desired pty slave Date: Tue, 8 Sep 2009 10:09:44 +0200 Message-ID: <20090908080944.GP12824@hawkmoon.kerlabs.com> References: <1252074054-22241-1-git-send-email-orenl@librato.com> <1252074054-22241-3-git-send-email-orenl@librato.com> <20090904152644.GA15253@us.ibm.com> Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============8735788150404148434==" Return-path: In-Reply-To: <20090904152644.GA15253-r/Jw6+rmf7HQT0dZR+AlfA@public.gmane.org> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Mime-version: 1.0 Sender: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org Errors-To: containers-bounces-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org To: "Serge E. Hallyn" Cc: containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org List-Id: containers.vger.kernel.org This is a MIME-formatted message. If you see this text it means that your E-mail software does not support MIME-formatted messages. --===============8735788150404148434== Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="=_bohort-21780-1252397343-0001-2" Content-Disposition: inline This is a MIME-formatted message. If you see this text it means that your E-mail software does not support MIME-formatted messages. --=_bohort-21780-1252397343-0001-2 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On 04/09/09 10:26 -0500, Serge E. Hallyn wrote: > Quoting Oren Laadan (orenl-RdfvBDnrOixBDgjK7y7TUQ@public.gmane.org): > > During restart, we need to allocate pty slaves with the same > > identifiers as recorded during checkpoint. Modify the allocation code > > to allow an in-kernel caller to request a specific slave identifier. > >=20 > > For this, add a new field to task_struct - 'required_id'. It will > > hold the desired identifier when restoring a (master) pty. > >=20 > > The code in ptmx_open() will use this value only for tasks that try to > > open /dev/ptmx that are restarting (PF_RESTARTING), and if the value > > isn't CKPT_REQUIRED_NONE (-1). >=20 > So noone has indicated any preference for this versus the ptmx_create() > approach... >=20 > I'm satisfied knowing we have a working fallback in case task->required_id > is deemed unacceptable. >=20 > However I'd like to not have linux-kernel folks think us morons for not > having considered that. Can you add a message to the changelog saying > why we're going with this approach (namely, that it lets us re-use > filp_open() instead of having to do a custom alloc_file in a new code-pat= h, > which introduces maintenance duplication for file permission checking > paths)? As far as I am concerned, I do have a preference for the ptmx_create() approach. This task->required_id field reminds me the former approach taken= for restarting pids and (and SYSV IPC ids IIRC) from userspace, that was propos= ed last year and actually deemed unacceptable [ IIRC, this was an argument in = favor of a restart() syscall ]. I know that it's not the same since ->required_id= is not set from userspace and used in a later syscall, but still ... Moreover I see no reason whey there would be no way to refactorize ptmx cod= e and have less duplicated code with the ptmx_create() approach. Thanks, Louis --=20 Dr Louis Rilling Kerlabs Skype: louis.rilling Batiment Germanium Phone: (+33|0) 6 80 89 08 23 80 avenue des Buttes de Coesmes http://www.kerlabs.com/ 35700 Rennes --=_bohort-21780-1252397343-0001-2 Content-Type: application/pgp-signature; name="signature.asc" Content-Transfer-Encoding: 7bit Content-Description: Digital signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.9 (GNU/Linux) iEYEARECAAYFAkqmEUgACgkQVKcRuvQ9Q1SH0ACgrwJYp6EJ/53diAxPJPFzNMoI VgQAoM/0BcUzG9YjA2YwTlOAxZM3F8gn =Ummz -----END PGP SIGNATURE----- --=_bohort-21780-1252397343-0001-2-- --===============8735788150404148434== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ Containers mailing list Containers-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org https://lists.linux-foundation.org/mailman/listinfo/containers --===============8735788150404148434==--