From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752514AbdARPrA (ORCPT ); Wed, 18 Jan 2017 10:47:00 -0500 Received: from mx2.suse.de ([195.135.220.15]:57339 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751908AbdARPq7 (ORCPT ); Wed, 18 Jan 2017 10:46:59 -0500 Date: Wed, 18 Jan 2017 16:44:31 +0100 From: Michal Hocko To: linux-api@vger.kernel.org Cc: Michael Kerrisk , Al Viro , LKML Subject: writev error codes Message-ID: <20170118154431.GD7021@dhcp22.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.6.0 (2016-04-01) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, we have noticed that one of the LTP tests started to fail after 99526912c934 ("fix iov_iter_fault_in_readable()"). The code has expected EINVAL while it gets EFAULT. I believe the new behavior is reasonable, but checking the man 2 writev, there is no mention about EFAULT, and other errnos for that matter, so it seems this is rather under documented and it can confuse users. LTP has been fixed in the meantime [1] but this might come unexpected to others. In principle writev as a write "multiplier" should be allowed all the error codes that write(2) allows, right? I am not sure how we should reflect that. Either c&p what we have in man 2 write or put a reference to it and only describe writev specific, if there are any (I haven't checked that). [1] https://github.com/linux-test-project/ltp/commit/db19194527060a962955a7db54a2f5710e69bec9 -- Michal Hocko SUSE Labs