From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754021AbcENUj0 (ORCPT ); Sat, 14 May 2016 16:39:26 -0400 Received: from mail-wm0-f54.google.com ([74.125.82.54]:36445 "EHLO mail-wm0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753905AbcENUjY convert rfc822-to-8bit (ORCPT ); Sat, 14 May 2016 16:39:24 -0400 From: Michal Nazarewicz To: Alan Stern , Felipe Balbi Cc: "Du\, Changbin" , Al Viro , "gregkh\@linuxfoundation.org" , "rui.silva\@linaro.org" , "k.opasiak\@samsung.com" , "lars\@metafoo.de" , "linux-usb\@vger.kernel.org" , "linux-kernel\@vger.kernel.org" Subject: Re: [PATCH] usb: gadget: f_fs: report error if excess data received In-Reply-To: Organization: http://mina86.com/ References: User-Agent: Notmuch/0.19+53~g2e63a09 (http://notmuchmail.org) Emacs/25.1.50.1 (x86_64-unknown-linux-gnu) Face: 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 X-Face: -TR8(rDTHy/(xl?SfWd1|3:TTgDIatE^t'vop%*gVg[kn$t{EpK(P"VQ=~T2#ysNmJKN$"yTRLB4YQs$4{[.]Fc1)*O]3+XO^oXM>Q#b^ix,O)Zbn)q[y06$`e3?C)`CwR9y5riE=fv^X@x$y?D:XO6L&x4f-}}I4=VRNwiA^t1-ZrVK^07.Pi/57c_du'& X-PGP: 50751FF4 X-PGP-FP: AC1F 5F5C D418 88F8 CC84 5858 2060 4012 5075 1FF4 X-Hashcash: 1:20:160514:k.opasiak@samsung.com::uTvEYwz78fWzj7T/:00000000000000000000000000000000000000001DZd X-Hashcash: 1:20:160514:lars@metafoo.de::NrGCjgKHAV3rmLo0:0016gd X-Hashcash: 1:20:160514:linux-kernel@vger.kernel.org::EVz23TOhd0muzkSM:0000000000000000000000000000000003PXW X-Hashcash: 1:20:160514:linux-usb@vger.kernel.org::cyMGnu1x4rHJLRZD:0000000000000000000000000000000000004cRB X-Hashcash: 1:20:160514:rui.silva@linaro.org::cf5hpiEnRaD1HAsi:0000000000000000000000000000000000000000022GS X-Hashcash: 1:20:160514:gregkh@linuxfoundation.org::HjxUXXLKhstfqwBL:000000000000000000000000000000000009F8v X-Hashcash: 1:20:160514:viro@zeniv.linux.org.uk::etPCpRU1e7IzW4TQ:000000000000000000000000000000000000008BqA X-Hashcash: 1:20:160514:changbin.du@intel.com::0ixlx+eQEmtZRGDo:00000000000000000000000000000000000000005fu9 X-Hashcash: 1:20:160514:felipe.balbi@linux.intel.com::1nikKX9ETv01Q9gj:0000000000000000000000000000000002A3H X-Hashcash: 1:20:160514:stern@rowland.harvard.edu::QwmAWRYeGy992B/J:0000000000000000000000000000000000005eF7 Date: Sat, 14 May 2016 22:39:18 +0200 Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, May 13 2016, Alan Stern wrote: > The point is that you don't know whether the host sent more data than > expected. All you know is that the host sent more data than the user > asked the kernel for -- but maybe the user didn't ask for all the data > that he expected. Maybe the user wanted to retrieve the full set of > data using two read() system calls. I was wondering about that for a while actually. So far, f_fs’ model was: one read, one request. Splitting requests would certainly be possible, but is that what f_fs’ users would expect to happen if host rounds the request up? -- Best regards ミハウ “𝓶𝓲𝓷𝓪86” ナザレヴイツ «If at first you don’t succeed, give up skydiving»