From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mails.dpdk.org (mails.dpdk.org [217.70.189.124]) by inbox.dpdk.org (Postfix) with ESMTP id 56769A0032; Thu, 16 Dec 2021 00:15:53 +0100 (CET) Received: from [217.70.189.124] (localhost [127.0.0.1]) by mails.dpdk.org (Postfix) with ESMTP id C86F840696; Thu, 16 Dec 2021 00:15:52 +0100 (CET) Received: from mail-pl1-f182.google.com (mail-pl1-f182.google.com [209.85.214.182]) by mails.dpdk.org (Postfix) with ESMTP id A562D40688 for ; Thu, 16 Dec 2021 00:15:50 +0100 (CET) Received: by mail-pl1-f182.google.com with SMTP id u17so17853661plg.9 for ; Wed, 15 Dec 2021 15:15:50 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=networkplumber-org.20210112.gappssmtp.com; s=20210112; h=date:from:to:cc:subject:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=M0WN4GSnNQ7BzkOjbJbnEbuZcOn32rc8GWv7lClD+vM=; b=DL88iI68QKl61Lv2Wmw9VhVkxPqnPBSCocaWBB6E2IeQVpHQIqkIJXHNDvNKUtJZWo YWwl4yAjHwGH0RZEJakrYy5Zz3SI1G0bOm2zY8CI7MlaRlR6Kap7PW5dE1154k6Z0FIj 24sQtRmbqa+ZoU/nR05kkcCTo5SSi1lYgfgav8M0fKGzQE091sGHkzfVX5CajZLq9SRH 76ZWq0Sx26hKpkGI7JQN3OfTXXoDBvF/uEtJwPEfdHyaMQoYp9YLQN65xgXJ807p9LBv y8BuUZCmZYk0+dT7wz8dG0vyvvcHMmpBX2y3jZXYq7ox1onu3wPnPKLLuNEIpW17bps5 Tz2g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:from:to:cc:subject:message-id:in-reply-to :references:mime-version:content-transfer-encoding; bh=M0WN4GSnNQ7BzkOjbJbnEbuZcOn32rc8GWv7lClD+vM=; b=GEyDz70FB5F8s9akc5c2gV6QjUcHeGR2Pn+D95YK804G2bCXMBCq3/P9Bi39Zf8UBM MYgKgxByIVzBqJvkJ8T5WJ7w4kNmG2LI/C1GfTY4cAVcTb3LnbSA5AmZD71Irdx8Dfuu MSf9yTzVjm7yAZIx0fI6wH8KKyuPXRze5hC2DEvp+a3y0kwLBBiOXW7Qx4UO2z/4Iewy p+4XL9plZdhYlYfu1P8j/13vV+wKOCjSK6hSWTdHuhZp1yxk+hS+3CIce4LHMVHbPphW PQ9l41S214Lakca1H/u4vcvqjXwcuhbUbhyPmUxFYQVKQoEzUaQ+f9gQ7WcwSiZa8mUy xK9g== X-Gm-Message-State: AOAM532i3tURnY6pUCf6PukgY79R2GbWgiB8Ua/yz/sD5Iv3wkQ0vRkZ RpcntTlD+b+TaX6XmnwNiLGoJOGA2enANQ== X-Google-Smtp-Source: ABdhPJzjG2OabZ3mmpPWihNDsFseZwoLGlrHIxRWlq5SPhbNeStEs0TaAVsuyu3NHMqXl5Myy19HgQ== X-Received: by 2002:a17:902:7b8e:b0:148:a2f7:9d8f with SMTP id w14-20020a1709027b8e00b00148a2f79d8fmr6588607pll.174.1639610149615; Wed, 15 Dec 2021 15:15:49 -0800 (PST) Received: from hermes.local (204-195-112-199.wavecable.com. [204.195.112.199]) by smtp.gmail.com with ESMTPSA id bf13sm2957849pjb.47.2021.12.15.15.15.48 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 15 Dec 2021 15:15:49 -0800 (PST) Date: Wed, 15 Dec 2021 15:15:46 -0800 From: Stephen Hemminger To: Ferruh Yigit Cc: Subject: Re: [dpdk-kmods] linux/igb_uio: fix build for switch fall through Message-ID: <20211215151546.40de01c3@hermes.local> In-Reply-To: <19cc482d-d7a4-7a14-a34f-33fd15a99a04@intel.com> References: <20211215184859.1859870-1-ferruh.yigit@intel.com> <20211215112017.26958d79@hermes.local> <19cc482d-d7a4-7a14-a34f-33fd15a99a04@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org On Wed, 15 Dec 2021 21:04:30 +0000 Ferruh Yigit wrote: > On 12/15/2021 7:20 PM, Stephen Hemminger wrote: > > On Wed, 15 Dec 2021 18:48:59 +0000 > > Ferruh Yigit wrote: > > > >> Linux is using '-Wimplicit-fallthrough=5' compiler option, which doesn't > >> take any fall through comments into account but only uses compiler > >> 'fallthrough' attribute to document fall through action is intended. > >> > >> "falls through" comment was used in the code which is causing a build > >> error now, this patch converts comment to the 'fallthrough' macro > >> defined in the Linux. > >> > >> To cover the case where Linux version doesn't have the macro, defined it > >> in the compatibility header too. > >> > >> Signed-off-by: Ferruh Yigit > > > > Are you sure that fixes it? because the comment in the macro is typically > > not visible in a macro expansion. > > Since in most case Linux uses gcc why not use the gcc attribute > > > > __attribute__ ((fallthrough)) > > Hi Stephen, > > That is the intention already. > > Patch is using the Linux kernel defined macro: > #if __has_attribute(__fallthrough__) > # define fallthrough __attribute__((__fallthrough__)) > #else > # define fallthrough do {} while (0) /* fallthrough */ > #endif > > And it builds fine without the macro in the 'compat.h'. > > > I added the define in the 'compat.h' for old kernels which doesn't > define the macro. For that case I expect default '-Wimplicit-fallthrough' > option is used which accepts 'fallthrough;' as a regex hit. Your right, on older kernels it really is just a dummy statement. The regex can't work, you can take (or leave the comment) it has no effect because implicit-fallthrough won't see it in a macro.