From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752821AbbIPRpl (ORCPT ); Wed, 16 Sep 2015 13:45:41 -0400 Received: from mail-yk0-f180.google.com ([209.85.160.180]:34930 "EHLO mail-yk0-f180.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752498AbbIPRpk (ORCPT ); Wed, 16 Sep 2015 13:45:40 -0400 Date: Wed, 16 Sep 2015 13:45:36 -0400 From: Tejun Heo To: Rasmus Villemoes Cc: Maurizio Lombardi , joe@perches.com, linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH 0/3] fix *pbl format support Message-ID: <20150916174536.GE3243@mtj.duckdns.org> References: <1442394523-19176-1-git-send-email-mlombard@redhat.com> <87d1xi4kic.fsf@rasmusvillemoes.dk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87d1xi4kic.fsf@rasmusvillemoes.dk> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, On Wed, Sep 16, 2015 at 02:27:23PM +0200, Rasmus Villemoes wrote: > If we want to fix the problem with 3/3, then this seems obviously > necessary. There may be stuff we want to optimize later (for example, I > don't think we should always make a local copy of the entire struct; if > we're only modifying one of the fields, it's better to copy that field > to a local variable and use that). Yeap. ... > I may have misread, or it might be fixable, but I really don't like > playing these subtle games. snprintf already provides a method to > reliably detect truncation; it is up to the user to decide whether and > how to deal with that. But yes, this of course requires that snprintf > actually attempted to format the entire bitmap, which in turn requires > some way to pass the correct size all the way through to the bitmap > formatter. Agreed again. > > PATCH 3 increases the size of printf_spec.field_width (from s16 to s32). > > I'm not yet completely convinced this is the right solution. Obviously, > if other problems with the small .field_width size show up, this might > be necessary, but as long as it's only the %pb formatter (and so far > only a single user of that), I think smaller/other hammers should be > thought about. So far I think there've been two alternatives: (1) > reintroduce the dedicated bitmap pretty printer(s), (2) my half-ugly > proposal allowing the user to pass struct printf_bitmap to the %pbh[l] > specifier. I'll try to actually code up (2). I suppose (2) could work too but we really should strive to provide something convenient to print[fk] users. The balance here is pretty one-sided. Thanks. -- tejun