Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933782AbXLOERY (ORCPT ); Fri, 14 Dec 2007 23:17:24 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1763816AbXLOERI (ORCPT ); Fri, 14 Dec 2007 23:17:08 -0500 Received: from rhun.apana.org.au ([64.62.148.172]:1683 "EHLO arnor.apana.org.au" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1755284AbXLOERH (ORCPT ); Fri, 14 Dec 2007 23:17:07 -0500 Date: Sat, 15 Dec 2007 12:16:59 +0800 From: Herbert Xu To: Matt Mackall Cc: Andrew Morton , Linux Kernel Mailing List Subject: Re: [PATCH] Make WARN_ON/WARN_ON_ONCE no-ops when CONFIG_BUG is off Message-ID: <20071215041659.GB25324@gondor.apana.org.au> References: <20071214132755.GA18309@gondor.apana.org.au> <20071214180246.GT17536@waste.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20071214180246.GT17536@waste.org> User-Agent: Mutt/1.5.9i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1390 Lines: 35 On Fri, Dec 14, 2007 at 12:02:46PM -0600, Matt Mackall wrote: > > I added CONFIG_BUG, and I think the current behavior is correct. As > you've noticed, we have to evaluate condition, it may have > side-effects. And if code does: > > /* this indicates a driver bug, report and fail gracefully */ > if (WARN_ON(val == NULL)) > return -EFAULT; That's exactly the sort of use I had in mind :) I'm actually the one who added the ability to use WARN_ON inside an if clause. Just as the case of a BUG_ON, a WARN_ON should never occur in practice, unless there is a bug which the code is not aware of. As such we want it to go away completely if CONFIG_BUG is off. > ..we surely want it to continue returning -EFAULT, regardless of > whether we log it, no? What use case did you have in mind? If you're using it for a scenario which is known to actually occur, then some other mechanism should be chosen in place of WARN_ON. Cheers, -- Visit Openswan at http://www.openswan.org/ Email: Herbert Xu ~{PmV>HI~} Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/