Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753562AbbGSP1j (ORCPT ); Sun, 19 Jul 2015 11:27:39 -0400 Received: from bh-25.webhostbox.net ([208.91.199.152]:48931 "EHLO bh-25.webhostbox.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753158AbbGSP1i (ORCPT ); Sun, 19 Jul 2015 11:27:38 -0400 Date: Sun, 19 Jul 2015 08:27:24 -0700 From: Guenter Roeck To: Sowmini Varadhan Cc: linux-kernel@vger.kernel.org, akpm@linux-foundation.org, benh@kernel.crashing.org, davem@davemloft.net Subject: Re: [PATCH] iommu-common: Do not use 64 bit constant 0xffffffffffffffffl for computing align_mask Message-ID: <20150719152724.GB3729@roeck-us.net> References: <20150719121653.GA30645@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150719121653.GA30645@oracle.com> User-Agent: Mutt/1.5.23 (2014-03-12) X-Authenticated_sender: guenter@roeck-us.net X-OutGoing-Spam-Status: No, score=-1.0 X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - bh-25.webhostbox.net X-AntiAbuse: Original Domain - vger.kernel.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - roeck-us.net X-Get-Message-Sender-Via: bh-25.webhostbox.net: authenticated_id: guenter@roeck-us.net X-Source: X-Source-Args: X-Source-Dir: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1325 Lines: 35 On Sun, Jul 19, 2015 at 02:20:14PM +0200, Sowmini Varadhan wrote: > > Using a 64 bit constant generates "warning: integer constant is too > large for 'long' type" on 32 bit platforms. Instead use ~0l to get > the desired effect. > > Detected by Andrew Morton who has confirmed that this patch > fixes the warning on i386/gcc-4.4.3, i386/gcc-4.4.0 and arm/gcc-4.4.4. > > Signed-off-by: Sowmini Varadhan > --- > lib/iommu-common.c | 2 +- > 1 files changed, 1 insertions(+), 1 deletions(-) > > diff --git a/lib/iommu-common.c b/lib/iommu-common.c > index df30632..fd1297d 100644 > --- a/lib/iommu-common.c > +++ b/lib/iommu-common.c > @@ -119,7 +119,7 @@ unsigned long iommu_tbl_range_alloc(struct device *dev, > unsigned long align_mask = 0; > > if (align_order > 0) > - align_mask = 0xffffffffffffffffl >> (64 - align_order); > + align_mask = ~0l >> (64 - align_order); > Wonder if this just hides the real problem. Unless align_order is very large, the resulting mask on 32 bit systems may be 0. Is this really the idea ? Guenter -- 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/