From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 41BFCC43381 for ; Thu, 7 Mar 2019 08:01:21 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0836320835 for ; Thu, 7 Mar 2019 08:01:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726194AbfCGIBT (ORCPT ); Thu, 7 Mar 2019 03:01:19 -0500 Received: from mout.kundenserver.de ([212.227.17.24]:54495 "EHLO mout.kundenserver.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725788AbfCGIBS (ORCPT ); Thu, 7 Mar 2019 03:01:18 -0500 Received: from wuerfel.lan ([109.192.41.194]) by mrelayeu.kundenserver.de (mreue107 [212.227.15.145]) with ESMTPA (Nemesis) id 1MsZeX-1gn0pF0d0l-00txjM; Thu, 07 Mar 2019 09:00:42 +0100 From: Arnd Bergmann To: Christoph Hellwig , Marek Szyprowski Cc: Nick Desaulniers , Arnd Bergmann , Robin Murphy , Jesper Dangaard Brouer , Paul Burton , Geert Uytterhoeven , iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org Subject: [PATCH] dma-mapping: work around clang bug Date: Thu, 7 Mar 2019 09:00:25 +0100 Message-Id: <20190307080038.3727426-1-arnd@arndb.de> X-Mailer: git-send-email 2.20.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Provags-ID: V03:K1:SnRTwP7mB1YqM4Ju0tIDBNxdpmKOjjsaltQRQqdqOs6SJgdPNEG qML6XcUhF83mtJcarIloWoyYtOlTZRao8xWFZctzxcOcvIvMuMEC3T0WBd2LMr2C+hwp1Sh x7KZlWkdTHteysVNHEyw89nSiSqz5aOMWlbXYCdUA5npGURM0KWRJKTeoYYwyh2H7oaui9m qtpISyDN3FdrO/Th/ZuZg== X-UI-Out-Filterresults: notjunk:1;V03:K0:mvI6dVuhiUU=:/R7VamLGMWNcYf311jvRHq qg0QfAvZnVzoUfZKJaapNdto//AYugPjk5TYwiMvo3NpB7Zb/tZJ3fZm/F3scEAv24S463rgW YqiqJVnNprt4WuyRaDZ67D2SxgSGMNu8EuY9g0GsZB2pruo35JYQedX36NQptfcdLu6jokkRK FOUQ/nPAmKNhRCRzE9/6dRjgI6y0FQZfd3VmFShAbAZSz9I9tGWQ+VC9t/ux4KMo4HGEK9m+s 5uKDeBp+OTqmWSVc4ys6isJImPoCspCrO0FxtwuIbDSZJ5GRwdtptYmDy2lfnDoWO1i/dBrX5 b4m7XHuxEGWzy3QOZvfVnrmPftbolGx7NKPbA+znCw40zy89WXHeAuqt+hTNrfZ6dn4MzsBiZ EX9NNoBL88W6nD1ICcaQFWdihFdWCvfxFcTwPKiOIbFG18W2CSuk2oKJOW1kfowyzPOiav+8c /1BLIwPSaRdRKPslVqQb5yHOBF4pkDstbxm14tN5FNkeYIdJpqjmysPhhQ5r0dU6zEr2EmPqL ZvnQypB+1kOleJhFxwWc1VcDJYO7XzUDg+Ja9dfQttxlSQVMmGfb60W5zUA/kuR+/9jbW8dK9 wjzPe+CewWmcZu84AlZLkqj0ts7BOaLG4CustNA7jiheu3V90/CDJKIfgEll6KHOsRmix4mqv oU8JYMjr2tLLCVE0TsUuZeIVdpquitA5p2Fi8cPlQa/fnmtm1o2ttJk/Y9zHpm4kccZz4qqla H83h4kxVORszuMisF5pRZHqg5sHXCCo8ZqcKjA== Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Clang has a rather annoying behavior of checking for integer arithmetic problems in code paths that are discarded by gcc before that perfoms the same checks. For DMA_BIT_MASK(64), this leads to a warning despite the result of the macro being completely sensible: arch/arm/plat-iop/adma.c:146:24: error: shift count >= width of type [-Werror,-Wshift-count-overflow] .coherent_dma_mask = DMA_BIT_MASK(64), The best workaround I could come up with is to shift the value twice, which makes the macro way less readable but always has the same result. Link: https://bugs.llvm.org/show_bug.cgi?id=38789 Signed-off-by: Arnd Bergmann --- include/linux/dma-mapping.h | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/include/linux/dma-mapping.h b/include/linux/dma-mapping.h index 75e60be91e5f..380d3a95d02e 100644 --- a/include/linux/dma-mapping.h +++ b/include/linux/dma-mapping.h @@ -138,7 +138,8 @@ struct dma_map_ops { extern const struct dma_map_ops dma_virt_ops; extern const struct dma_map_ops dma_dummy_ops; -#define DMA_BIT_MASK(n) (((n) == 64) ? ~0ULL : ((1ULL<<(n))-1)) +/* double shift to work around https://bugs.llvm.org/show_bug.cgi?id=38789 */ +#define DMA_BIT_MASK(n) (((n) == 64) ? ~0ULL : (((1ULL<<((n)-1))-1) << 1)) #define DMA_MASK_NONE 0x0ULL -- 2.20.0