From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.kernel.org ([198.145.29.99]:57686 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728455AbeIQVxE (ORCPT ); Mon, 17 Sep 2018 17:53:04 -0400 Message-ID: Subject: Re: [RFC][PATCH 0/3] exec: Moving unshare_files_struct From: Jeff Layton To: "Eric W. Biederman" Cc: viro@zeniv.linux.org.uk, berrange@redhat.com, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Oleg Nesterov Date: Mon, 17 Sep 2018 12:24:57 -0400 In-Reply-To: <87a7ohs5ow.fsf@xmission.com> References: <20180914105310.6454-1-jlayton@kernel.org> <87a7ohs5ow.fsf@xmission.com> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Sun, 2018-09-16 at 19:38 +0200, Eric W. Biederman wrote: > Paired with Oleg's patch to reduce the number of callers of > get_files_struct it looks like we can simplify the basic idea of moving > unshare_files in exec by quite a bit so that in net we have fewer lines > of code. > > The big simplification from Jeff's verion is that we take advantage > of calling unshare_files past the point of no return. Which removes > the need for cleanup, and restoring ->files. Which removes the > need for blocking clone and unshare. > > Oleg's patch to remove get_files_struct from proc means we don't need > two counts in files_struct. > > Which leaves us with the question of what are the races in fs/exec.c > with respect to accessing files. Semantically I don't think we care > but we do need to be certain the implementation of exec is still robust. > > These patches are still rough and ready and only compile tested but I > believe they demonstrate what is possible. > > Eric W. Biederman (3): > exec: Move unshare_files down to avoid locks being dropped on exec. > exec: Simplify unshare_files > exec: Remove reset_files_struct > > fs/coredump.c | 5 +---- > fs/exec.c | 16 +++++----------- > fs/file.c | 12 ------------ > include/linux/fdtable.h | 3 +-- > kernel/fork.c | 12 ++++++------ > 5 files changed, 13 insertions(+), 35 deletions(-) > > Eric Much better than what I had proposed and I do like that diffstat. You can add this from me too: Reviewed-by: Jeff Layton Maybe get this into -next soon once it has passed some sanity tests? Thanks, -- Jeff Layton