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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,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 8E723C2D0DB for ; Wed, 22 Jan 2020 09:54:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5BA172465A for ; Wed, 22 Jan 2020 09:54:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579686885; bh=VlQofBDHMV6J8ChWsXE3ce4pYUd7IvENMJgCbarV/wo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=LyoYLYplUC0qN8QyzXe6r/Nl8K0U6ppfJYWeOKkKajlNhmO/jva9IA8e262PnP1So 2JsdIgMB+JQNXZ+2wiqONqYZNno9IHrRcE8ACM7/8xCW0pPwhuz8Z6je8I+Ayt75x1 tdxrtKGCbb2SaOYaHbdlurxCma0pnVml1fpGi9kI= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731508AbgAVJyo (ORCPT ); Wed, 22 Jan 2020 04:54:44 -0500 Received: from mail.kernel.org ([198.145.29.99]:47988 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730051AbgAVJdv (ORCPT ); Wed, 22 Jan 2020 04:33:51 -0500 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 7AB9124672; Wed, 22 Jan 2020 09:33:50 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579685631; bh=VlQofBDHMV6J8ChWsXE3ce4pYUd7IvENMJgCbarV/wo=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=W9CyXGKieU1AeV+69VOlrmmW03JHe2JCeMHp5AhCKmjpsQMm4giiSFyJ/LlhNjNwS E0N3a8A+ozyrwXHfIBdPXSQKZax5+y3+19FMFffKcN91urbP8ECsoB03Po2Rz6TyeU UhLJT7LydV7ueao7GZNSO4/BhEyj+Ur7PIZQjU1c= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Arnd Bergmann , Andi Kleen , Nick Desaulniers , Alexander Viro , Christoph Hellwig , Eric Dumazet , "Darrick J. Wong" , Andrew Morton , Linus Torvalds , Miles Chen Subject: [PATCH 4.9 05/97] fs/select: avoid clang stack usage warning Date: Wed, 22 Jan 2020 10:28:09 +0100 Message-Id: <20200122092756.601582145@linuxfoundation.org> X-Mailer: git-send-email 2.25.0 In-Reply-To: <20200122092755.678349497@linuxfoundation.org> References: <20200122092755.678349497@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Arnd Bergmann commit ad312f95d41c9de19313c51e388c4984451c010f upstream. The select() implementation is carefully tuned to put a sensible amount of data on the stack for holding a copy of the user space fd_set, but not too large to risk overflowing the kernel stack. When building a 32-bit kernel with clang, we need a little more space than with gcc, which often triggers a warning: fs/select.c:619:5: error: stack frame size of 1048 bytes in function 'core_sys_select' [-Werror,-Wframe-larger-than=] int core_sys_select(int n, fd_set __user *inp, fd_set __user *outp, I experimentally found that for 32-bit ARM, reducing the maximum stack usage by 64 bytes keeps us reliably under the warning limit again. Link: http://lkml.kernel.org/r/20190307090146.1874906-1-arnd@arndb.de Signed-off-by: Arnd Bergmann Reviewed-by: Andi Kleen Cc: Nick Desaulniers Cc: Alexander Viro Cc: Christoph Hellwig Cc: Eric Dumazet Cc: "Darrick J. Wong" Cc: Greg Kroah-Hartman Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Miles Chen Signed-off-by: Greg Kroah-Hartman --- include/linux/poll.h | 4 ++++ 1 file changed, 4 insertions(+) --- a/include/linux/poll.h +++ b/include/linux/poll.h @@ -14,7 +14,11 @@ extern struct ctl_table epoll_table[]; /* for sysctl */ /* ~832 bytes of stack space used max in sys_select/sys_poll before allocating additional memory. */ +#ifdef __clang__ +#define MAX_STACK_ALLOC 768 +#else #define MAX_STACK_ALLOC 832 +#endif #define FRONTEND_STACK_ALLOC 256 #define SELECT_STACK_ALLOC FRONTEND_STACK_ALLOC #define POLL_STACK_ALLOC FRONTEND_STACK_ALLOC