From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.0 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 00DF4C43387 for ; Wed, 16 Jan 2019 15:32:09 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C4A0920675 for ; Wed, 16 Jan 2019 15:32:08 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=kernel-dk.20150623.gappssmtp.com header.i=@kernel-dk.20150623.gappssmtp.com header.b="FRChQ7BE" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2391280AbfAPPcI (ORCPT ); Wed, 16 Jan 2019 10:32:08 -0500 Received: from mail-io1-f68.google.com ([209.85.166.68]:42127 "EHLO mail-io1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2394079AbfAPPcH (ORCPT ); Wed, 16 Jan 2019 10:32:07 -0500 Received: by mail-io1-f68.google.com with SMTP id x6so5169214ioa.9 for ; Wed, 16 Jan 2019 07:32:07 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20150623.gappssmtp.com; s=20150623; h=subject:from:to:cc:references:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=ZiQ+uyqTl1b+kMcXwyfjNQaFPy8JWmeE+avUtD8CbTA=; b=FRChQ7BE7L6zmXoWceUkMK4c93+ki0+XPg14TBYLRTCH/T+g2p3GXCIqQGwXGyEDgl u3z08X+CFam19iMxcZvK7o1oxe/RWgjZhGRxJ155ebLxiakBYmOegMzkrb6fphtHwMhI YmWqpFQ8Qjl6554bkHpldpl2066hfhg0VVEIENepDH1ChKAqmslebteviJjNK0cFKb9S lL6kvfb9bvG4D8AM7G8nZpZClHfv0wPwM39TrJDZv3aKCTQ0kYsvPXsKjeoThAANCzAe DTBdYAdxgHCpRimTRsVwTVL0pj3uJa0QeKvIj5eAovIBPYM0x4T1JpevSrHJvbAhwrMq OjqQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:from:to:cc:references:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=ZiQ+uyqTl1b+kMcXwyfjNQaFPy8JWmeE+avUtD8CbTA=; b=HrIt5wuRJCQwl0kIjCiZBWr1hHJddsxOrtw0Av0qUuI2M2ZvMC3GDKeG07BQC+0EMH d+4eTmcJvSgnuNg+vAWdJ7K7D74yKIbugN0GszQgECXvHCqBObxRBAFFRXj1ABlVLsjz 08/jt9JXeSLTgQfKDOix94zg9DzjcrDeA5IPF2CcZDHBAtd9yQ7+d4dv5hiVKsLapk67 i2ym8edZjZlSkCv+rgTPy1kLMJxi4LAtmKdxutKU6arACInm0rooGaXyrylYkcRkXItx Vd4pGjAI46JYhSjM5Op/VybaBO3SrF+eL1bOVKt6vA2Wid+wur+aMsjVfWeF38yuoGWh AREQ== X-Gm-Message-State: AJcUukdUvcxoyKQgnbbpnnYRqw3HI3nStjRSlm7+TVRyEf05DYKcmJLp CgDJTVc4DVbjjXidd1Xy/HuUUA== X-Google-Smtp-Source: ALg8bN6Up1D9FTx/nEwVGNAPFfGzW3ol36ks8i/vDS1Rdo9t98qrypSRNGOCc/D6FM4EWnB9bifdvQ== X-Received: by 2002:a6b:6919:: with SMTP id e25mr4948858ioc.119.1547652726606; Wed, 16 Jan 2019 07:32:06 -0800 (PST) Received: from [192.168.1.56] ([216.160.245.98]) by smtp.gmail.com with ESMTPSA id m81sm3406151itb.43.2019.01.16.07.32.04 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 16 Jan 2019 07:32:05 -0800 (PST) Subject: Re: [PATCH 13/16] io_uring: add support for pre-mapped user IO buffers From: Jens Axboe To: Arnd Bergmann Cc: Linux FS-devel Mailing List , linux-aio , linux-block , linux-arch , Christoph Hellwig , Jeff Moyer , Avi Kivity References: <20190115025531.13985-1-axboe@kernel.dk> <20190115025531.13985-14-axboe@kernel.dk> <075af26b-c685-a0db-05e4-fa73f8725b8a@kernel.dk> Message-ID: <331f63c0-002f-b373-b831-73af9e98f2ef@kernel.dk> Date: Wed, 16 Jan 2019 08:32:03 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.2.1 MIME-Version: 1.0 In-Reply-To: <075af26b-c685-a0db-05e4-fa73f8725b8a@kernel.dk> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-block-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-block@vger.kernel.org On 1/16/19 8:14 AM, Jens Axboe wrote: > On 1/16/19 3:53 AM, Arnd Bergmann wrote: >> On Tue, Jan 15, 2019 at 3:56 AM Jens Axboe wrote: >> >>> diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h >>> index 542757a4c898..e36c264d74e8 100644 >>> --- a/include/linux/syscalls.h >>> +++ b/include/linux/syscalls.h >>> @@ -314,6 +314,8 @@ asmlinkage long sys_io_uring_setup(u32 entries, >>> struct io_uring_params __user *p); >>> asmlinkage long sys_io_uring_enter(unsigned int fd, u32 to_submit, >>> u32 min_complete, u32 flags); >>> +asmlinkage long sys_io_uring_register(unsigned int fd, unsigned op, >>> + void __user *arg); >>> >> >> Would it be possible to make this a typed pointer instead? If this needs to >> be extended later to pass a different structure, a new system call may >> be better for consistency than overloading the argument in various >> ways. > > As you can see from the later patch for registering files, it'll be used > for other structs too. Feels a little silly to add an extra system call > for that. I agree the void * isn't the prettiest thing in the world, but > at least it allows us to extend the API without having to add even more > system calls down the line. With the __u64 changes, we end up with this: struct io_uring_register_buffers { __u64 iovecs; /* pointer to iovecs array */ __u32 nr_iovecs; /* number of iovecs in array */ __u32 pad; }; struct io_uring_register_files { __u64 fds; __u32 nr_fds; __u32 pad; }; which are identical. So the question then becomes if I should just make these opaque enough to be the same thing, ala: struct io_uring_register_data { __u64 data; __u32 nr_elems; __u32 pad; }; and then probably add a bit more reserved space so we have something that can be extended... -- Jens Axboe