From mboxrd@z Thu Jan 1 00:00:00 1970 From: Josh Triplett Subject: Re: [PATCH] compiler: Correct macro parameter expansion problem Date: Mon, 3 Nov 2014 06:48:01 -0800 Message-ID: <20141103144800.GA23094@thin> References: <1415025253-15976-1-git-send-email-jeffrey.t.kirsher@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from relay6-d.mail.gandi.net ([217.70.183.198]:42004 "EHLO relay6-d.mail.gandi.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752375AbaKCOsN (ORCPT ); Mon, 3 Nov 2014 09:48:13 -0500 Content-Disposition: inline In-Reply-To: <1415025253-15976-1-git-send-email-jeffrey.t.kirsher@intel.com> Sender: linux-sparse-owner@vger.kernel.org List-Id: linux-sparse@vger.kernel.org To: Jeff Kirsher Cc: sparse@chrisli.org, Mark Rustad , linux-kernel@vger.kernel.org, linux-sparse@vger.kernel.org On Mon, Nov 03, 2014 at 06:34:13AM -0800, Jeff Kirsher wrote: > From: Mark Rustad > > The macro __compiletime_error_fallback has an error in that it > lacks parens around the expansion of an expression. It also > lacks a conversion to a boolean value. The first problem can > result in a mis-evaluation. The second problem can also result > in an error if the value comes out negative. That would thwart > the intended error generation. That is, the error being asserted > would not in fact generate an error. Fix both problems by adding > !!() to the expansion. > > Signed-off-by: Mark Rustad > Tested-by: Aaron Brown > Signed-off-by: Jeff Kirsher Good catch. Reviewed-by: Josh Triplett > include/linux/compiler.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/include/linux/compiler.h b/include/linux/compiler.h > index d5ad7b1..59dc611 100644 > --- a/include/linux/compiler.h > +++ b/include/linux/compiler.h > @@ -331,7 +331,7 @@ void ftrace_likely_update(struct ftrace_branch_data *f, int val, int expect); > */ > # ifndef __CHECKER__ > # define __compiletime_error_fallback(condition) \ > - do { ((void)sizeof(char[1 - 2 * condition])); } while (0) > + do { ((void)sizeof(char[1 - 2 * !!(condition)])); } while (0) > # endif > #endif > #ifndef __compiletime_error_fallback > -- > 1.9.3 > > -- > To unsubscribe from this list: send the line "unsubscribe linux-sparse" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html