From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751585AbaKEVGX (ORCPT ); Wed, 5 Nov 2014 16:06:23 -0500 Received: from cdptpa-outbound-snat.email.rr.com ([107.14.166.226]:9823 "EHLO cdptpa-oedge-vip.email.rr.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1751017AbaKEVGU (ORCPT ); Wed, 5 Nov 2014 16:06:20 -0500 Date: Wed, 5 Nov 2014 16:06:18 -0500 From: Steven Rostedt To: Petr Mladek Cc: linux-kernel@vger.kernel.org, Ingo Molnar , Andrew Morton , Jiri Kosina , "H. Peter Anvin" , Thomas Gleixner Subject: Re: [RFC][PATCH 07/12 v3] tracing: Have seq_buf use full buffer Message-ID: <20141105160618.6c684f23@gandalf.local.home> In-Reply-To: <20141105152130.09779ccf@gandalf.local.home> References: <20141104155237.228431433@goodmis.org> <20141104160222.502133196@goodmis.org> <20141105163150.GI4570@pathway.suse.cz> <20141105152130.09779ccf@gandalf.local.home> X-Mailer: Claws Mail 3.10.1 (GTK+ 2.24.25; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-RR-Connecting-IP: 107.14.168.142:25 X-Cloudmark-Score: 0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 5 Nov 2014 15:21:30 -0500 Steven Rostedt wrote: > > > > I wonder if we want this change at all. It means that we are not able to > > detect overflow in some functions. It is pity because the users > > might want to increase the buffer size and try again if the print > > was incomplete. > > What do you mean we can't detect overflow? That's what > seq_buf_has_overflowed() does. > Although I'm looking at the seq_file versions of the bitmap code, which does only return the len of what was written and not what would have been written, and it does have this issue. I hate to go back to the -1 of the size of buffer as that causes inconsistencies within the functions themselves, as proved with the seq_file code. What I might do as just have the bitmap calls not be allowed to fill the buffer and keep the logic the same. That is, if the bitmap calls fill the rest of the length, assume we overflowed, otherwise we are fine. I'm going to change seq_buf to do that instead of my new update with the bitmask code. -- Steve