From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jens Axboe Subject: Re: IORING_REGISTER_CREDS[_UPDATE]() and credfd_create()? Date: Tue, 28 Jan 2020 16:40:27 -0700 Message-ID: <6c401e23-de7c-1fc1-4122-33d53fcf9700@kernel.dk> References: <688e187a-75dd-89d9-921c-67de228605ce@samba.org> <1ac31828-e915-6180-cdb4-36685442ea75@kernel.dk> <0d4f43d8-a0c4-920b-5b8f-127c1c5a3fad@kernel.dk> <2d7e7fa2-e725-8beb-90b9-6476d48bdb33@gmail.com> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <2d7e7fa2-e725-8beb-90b9-6476d48bdb33-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org> Content-Language: en-US Sender: linux-api-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: Pavel Begunkov , Stefan Metzmacher Cc: io-uring , Linux API Mailing List List-Id: linux-api@vger.kernel.org On 1/28/20 4:36 PM, Pavel Begunkov wrote: > On 28/01/2020 22:42, Jens Axboe wrote: >> I didn't like it becoming a bit too complicated, both in terms of >> implementation and use. And the fact that we'd have to jump through >> hoops to make this work for a full chain. >> >> So I punted and just added sqe->personality and IOSQE_PERSONALITY. >> This makes it way easier to use. Same branch: >> >> https://git.kernel.dk/cgit/linux-block/log/?h=for-5.6/io_uring-vfs-creds >> >> I'd feel much better with this variant for 5.6. >> > > Checked out ("don't use static creds/mm assignments") > > 1. do we miscount cred refs? We grab one in get_current_cred() for each async > request, but if (worker->creds != work->creds) it will never be put. Yeah I think you're right, that needs a bit of fixing up. > 2. shouldn't worker->creds be named {old,saved,etc}_creds? It's set as > > worker->creds = override_creds(work->creds); > > Where override_creds() returns previous creds. And if so, then the following > fast check looks strange: > > worker->creds != work->creds Don't care too much about the naming, but the logic does appear off. I'll take a look at both of these tonight, unless you beat me to it. -- Jens Axboe