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=-3.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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 4CFA1C742D2 for ; Fri, 12 Jul 2019 22:36:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 1A0CB2146E for ; Fri, 12 Jul 2019 22:36:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728145AbfGLWge (ORCPT ); Fri, 12 Jul 2019 18:36:34 -0400 Received: from shards.monkeyblade.net ([23.128.96.9]:34334 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727994AbfGLWge (ORCPT ); Fri, 12 Jul 2019 18:36:34 -0400 Received: from localhost (unknown [IPv6:2601:601:9f80:35cd::d71]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (Client did not present a certificate) (Authenticated sender: davem-davemloft) by shards.monkeyblade.net (Postfix) with ESMTPSA id 9137F14E0384F; Fri, 12 Jul 2019 15:36:33 -0700 (PDT) Date: Fri, 12 Jul 2019 15:36:32 -0700 (PDT) Message-Id: <20190712.153632.1007215196498198399.davem@davemloft.net> To: arnd@arndb.de Cc: vishal@chelsio.com, rahul.lakkireddy@chelsio.com, ganeshgr@chelsio.com, alexios.zavras@intel.com, arjun@chelsio.com, surendra@chelsio.com, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, clang-built-linux@googlegroups.com Subject: Re: [PATCH] [net-next] cxgb4: reduce kernel stack usage in cudbg_collect_mem_region() From: David Miller In-Reply-To: <20190712090700.317887-1-arnd@arndb.de> References: <20190712090700.317887-1-arnd@arndb.de> X-Mailer: Mew version 6.8 on Emacs 26.1 Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.5.12 (shards.monkeyblade.net [149.20.54.216]); Fri, 12 Jul 2019 15:36:34 -0700 (PDT) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Arnd Bergmann Date: Fri, 12 Jul 2019 11:06:33 +0200 > The cudbg_collect_mem_region() and cudbg_read_fw_mem() both use several > hundred kilobytes of kernel stack space. One gets inlined into the other, > which causes the stack usage to be combined beyond the warning limit > when building with clang: > > drivers/net/ethernet/chelsio/cxgb4/cudbg_lib.c:1057:12: error: stack frame size of 1244 bytes in function 'cudbg_collect_mem_region' [-Werror,-Wframe-larger-than=] > > Restructuring cudbg_collect_mem_region() lets clang do the same > optimization that gcc does and reuse the stack slots as it can > see that the large variables are never used together. > > A better fix might be to avoid using cudbg_meminfo on the stack > altogether, but that requires a larger rewrite. > > Fixes: a1c69520f785 ("cxgb4: collect MC memory dump") > Signed-off-by: Arnd Bergmann Applied.