From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from dpdk.org (dpdk.org [92.243.14.124]) by inbox.dpdk.org (Postfix) with ESMTP id E4EB5A052E for ; Mon, 9 Mar 2020 12:30:03 +0100 (CET) Received: from [92.243.14.124] (localhost [127.0.0.1]) by dpdk.org (Postfix) with ESMTP id AE2D61BFED; Mon, 9 Mar 2020 12:30:03 +0100 (CET) Received: from mga09.intel.com (mga09.intel.com [134.134.136.24]) by dpdk.org (Postfix) with ESMTP id 74EF81BFF4; Mon, 9 Mar 2020 12:30:01 +0100 (CET) X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga007.jf.intel.com ([10.7.209.58]) by orsmga102.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 09 Mar 2020 04:30:00 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.70,533,1574150400"; d="scan'208";a="230893291" Received: from fyigit-mobl.ger.corp.intel.com (HELO [10.237.221.20]) ([10.237.221.20]) by orsmga007.jf.intel.com with ESMTP; 09 Mar 2020 04:29:56 -0700 To: Gavin Hu , "dev@dpdk.org" Cc: nd , "david.marchand@redhat.com" , "thomas@monjalon.net" , "ktraynor@redhat.com" , "jerinj@marvell.com" , Honnappa Nagarahalli , Ruifeng Wang , Phil Yang , Joyce Kong , "stable@dpdk.org" , Olivier MATZ , Konstantin Ananyev , Andrew Rybchenko References: <20200303162728.93744-1-gavin.hu@arm.com> <20200307155629.45021-1-gavin.hu@arm.com> <4135ab73-75d3-421a-264d-2951fc096133@intel.com> From: Ferruh Yigit Autocrypt: addr=ferruh.yigit@intel.com; prefer-encrypt=mutual; keydata= mQINBFXZCFABEADCujshBOAaqPZpwShdkzkyGpJ15lmxiSr3jVMqOtQS/sB3FYLT0/d3+bvy qbL9YnlbPyRvZfnP3pXiKwkRoR1RJwEo2BOf6hxdzTmLRtGtwWzI9MwrUPj6n/ldiD58VAGQ +iR1I/z9UBUN/ZMksElA2D7Jgg7vZ78iKwNnd+vLBD6I61kVrZ45Vjo3r+pPOByUBXOUlxp9 GWEKKIrJ4eogqkVNSixN16VYK7xR+5OUkBYUO+sE6etSxCr7BahMPKxH+XPlZZjKrxciaWQb +dElz3Ab4Opl+ZT/bK2huX+W+NJBEBVzjTkhjSTjcyRdxvS1gwWRuXqAml/sh+KQjPV1PPHF YK5LcqLkle+OKTCa82OvUb7cr+ALxATIZXQkgmn+zFT8UzSS3aiBBohg3BtbTIWy51jNlYdy ezUZ4UxKSsFuUTPt+JjHQBvF7WKbmNGS3fCid5Iag4tWOfZoqiCNzxApkVugltxoc6rG2TyX CmI2rP0mQ0GOsGXA3+3c1MCdQFzdIn/5tLBZyKy4F54UFo35eOX8/g7OaE+xrgY/4bZjpxC1 1pd66AAtKb3aNXpHvIfkVV6NYloo52H+FUE5ZDPNCGD0/btFGPWmWRmkPybzColTy7fmPaGz cBcEEqHK4T0aY4UJmE7Ylvg255Kz7s6wGZe6IR3N0cKNv++O7QARAQABtCVGZXJydWggWWln aXQgPGZlcnJ1aC55aWdpdEBpbnRlbC5jb20+iQJUBBMBCgA+AhsDAh4BAheABQsJCAcDBRUK CQgLBRYCAwEAFiEE0jZTh0IuwoTjmYHH+TPrQ98TYR8FAl1meboFCQlupOoACgkQ+TPrQ98T YR9ACBAAv2tomhyxY0Tp9Up7mNGLfEdBu/7joB/vIdqMRv63ojkwr9orQq5V16V/25+JEAD0 60cKodBDM6HdUvqLHatS8fooWRueSXHKYwJ3vxyB2tWDyZrLzLI1jxEvunGodoIzUOtum0Ce gPynnfQCelXBja0BwLXJMplM6TY1wXX22ap0ZViC0m714U5U4LQpzjabtFtjT8qOUR6L7hfy YQ72PBuktGb00UR/N5UrR6GqB0x4W41aZBHXfUQnvWIMmmCrRUJX36hOTYBzh+x86ULgg7H2 1499tA4o6rvE13FiGccplBNWCAIroAe/G11rdoN5NBgYVXu++38gTa/MBmIt6zRi6ch15oLA Ln2vHOdqhrgDuxjhMpG2bpNE36DG/V9WWyWdIRlz3NYPCDM/S3anbHlhjStXHOz1uHOnerXM 1jEjcsvmj1vSyYoQMyRcRJmBZLrekvgZeh7nJzbPHxtth8M7AoqiZ/o/BpYU+0xZ+J5/szWZ aYxxmIRu5ejFf+Wn9s5eXNHmyqxBidpCWvcbKYDBnkw2+Y9E5YTpL0mS0dCCOlrO7gca27ux ybtbj84aaW1g0CfIlUnOtHgMCmz6zPXThb+A8H8j3O6qmPoVqT3qnq3Uhy6GOoH8Fdu2Vchh TWiF5yo+pvUagQP6LpslffufSnu+RKAagkj7/RSuZV25Ag0EV9ZMvgEQAKc0Db17xNqtSwEv mfp4tkddwW9XA0tWWKtY4KUdd/jijYqc3fDD54ESYpV8QWj0xK4YM0dLxnDU2IYxjEshSB1T qAatVWz9WtBYvzalsyTqMKP3w34FciuL7orXP4AibPtrHuIXWQOBECcVZTTOdZYGAzaYzxiA ONzF9eTiwIqe9/oaOjTwTLnOarHt16QApTYQSnxDUQljeNvKYt1lZE/gAUUxNLWsYyTT+22/ vU0GDUahsJxs1+f1yEr+OGrFiEAmqrzpF0lCS3f/3HVTU6rS9cK3glVUeaTF4+1SK5ZNO35p iVQCwphmxa+dwTG/DvvHYCtgOZorTJ+OHfvCnSVjsM4kcXGjJPy3JZmUtyL9UxEbYlrffGPQ I3gLXIGD5AN5XdAXFCjjaID/KR1c9RHd7Oaw0Pdcq9UtMLgM1vdX8RlDuMGPrj5sQrRVbgYH fVU/TQCk1C9KhzOwg4Ap2T3tE1umY/DqrXQgsgH71PXFucVjOyHMYXXugLT8YQ0gcBPHy9mZ qw5mgOI5lCl6d4uCcUT0l/OEtPG/rA1lxz8ctdFBVOQOxCvwRG2QCgcJ/UTn5vlivul+cThi 6ERPvjqjblLncQtRg8izj2qgmwQkvfj+h7Ex88bI8iWtu5+I3K3LmNz/UxHBSWEmUnkg4fJl Rr7oItHsZ0ia6wWQ8lQnABEBAAGJAjwEGAEKACYCGwwWIQTSNlOHQi7ChOOZgcf5M+tD3xNh HwUCXWZ5wAUJB3FgggAKCRD5M+tD3xNhH2O+D/9OEz62YuJQLuIuOfL67eFTIB5/1+0j8Tsu o2psca1PUQ61SZJZOMl6VwNxpdvEaolVdrpnSxUF31kPEvR0Igy8HysQ11pj8AcgH0a9FrvU /8k2Roccd2ZIdpNLkirGFZR7LtRw41Kt1Jg+lafI0efkiHKMT/6D/P1EUp1RxOBNtWGV2hrd 0Yg9ds+VMphHHU69fDH02SwgpvXwG8Qm14Zi5WQ66R4CtTkHuYtA63sS17vMl8fDuTCtvfPF HzvdJLIhDYN3Mm1oMjKLlq4PUdYh68Fiwm+boJoBUFGuregJFlO3hM7uHBDhSEnXQr5mqpPM 6R/7Q5BjAxrwVBisH0yQGjsWlnysRWNfExAE2sRePSl0or9q19ddkRYltl6X4FDUXy2DTXa9 a+Fw4e1EvmcF3PjmTYs9IE3Vc64CRQXkhujcN4ZZh5lvOpU8WgyDxFq7bavFnSS6kx7Tk29/ wNJBp+cf9qsQxLbqhW5kfORuZGecus0TLcmpZEFKKjTJBK9gELRBB/zoN3j41hlEl7uTUXTI JQFLhpsFlEdKLujyvT/aCwP3XWT+B2uZDKrMAElF6ltpTxI53JYi22WO7NH7MR16Fhi4R6vh FHNBOkiAhUpoXRZXaCR6+X4qwA8CwHGqHRBfYFSU/Ulq1ZLR+S3hNj2mbnSx0lBs1eEqe2vh cA== Message-ID: Date: Mon, 9 Mar 2020 11:29:56 +0000 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Subject: Re: [dpdk-stable] [dpdk-dev] [PATCH v2] mbuf: replace zero-length marker with unnamed union X-BeenThere: stable@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: patches for DPDK stable branches List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: stable-bounces@dpdk.org Sender: "stable" On 3/9/2020 9:45 AM, Gavin Hu wrote: > Hi Ferruh, > >> -----Original Message----- >> From: Ferruh Yigit >> Sent: Monday, March 9, 2020 4:55 PM >> To: Gavin Hu ; dev@dpdk.org >> Cc: nd ; david.marchand@redhat.com; thomas@monjalon.net; >> ktraynor@redhat.com; jerinj@marvell.com; Honnappa Nagarahalli >> ; Ruifeng Wang >> ; Phil Yang ; Joyce Kong >> ; stable@dpdk.org; Olivier MATZ >> ; Konstantin Ananyev >> ; Andrew Rybchenko >> >> Subject: Re: [dpdk-dev] [PATCH v2] mbuf: replace zero-length marker with >> unnamed union >> >> On 3/7/2020 3:56 PM, Gavin Hu wrote: >>> Declaring zero-length arrays in other contexts, including as interior >>> members of structure objects or as non-member objects, is discouraged. >>> Accessing elements of zero-length arrays declared in such contexts is >>> undefined and may be diagnosed.[1] >>> >>> Fix by using unnamed union and struct. >>> >>> https://bugs.dpdk.org/show_bug.cgi?id=396 >>> >>> Bugzilla ID: 396 >>> >>> [1] https://gcc.gnu.org/onlinedocs/gcc/Zero-Length.html >>> >>> Fixes: 3e6181b07038 ("mbuf: use structure marker from EAL") >>> Cc: stable@dpdk.org >>> >>> Signed-off-by: Gavin Hu >>> --- >>> v2: >>> * change 'uint64_t rearm_data' to 'uint_64_t rearm_data[1]' to fix >>> the SFC PMD compiling error on x86. >>> --- >>> lib/librte_mbuf/rte_mbuf_core.h | 54 +++++++++++++++++++-------------- >>> 1 file changed, 32 insertions(+), 22 deletions(-) >>> >>> diff --git a/lib/librte_mbuf/rte_mbuf_core.h >> b/lib/librte_mbuf/rte_mbuf_core.h >>> index b9a59c879..34cb152e2 100644 >>> --- a/lib/librte_mbuf/rte_mbuf_core.h >>> +++ b/lib/librte_mbuf/rte_mbuf_core.h >>> @@ -480,31 +480,41 @@ struct rte_mbuf { >>> rte_iova_t buf_physaddr; /**< deprecated */ >>> } __rte_aligned(sizeof(rte_iova_t)); >>> >>> - /* next 8 bytes are initialised on RX descriptor rearm */ >>> - RTE_MARKER64 rearm_data; >>> - uint16_t data_off; >>> - >>> - /** >>> - * Reference counter. Its size should at least equal to the size >>> - * of port field (16 bits), to support zero-copy broadcast. >>> - * It should only be accessed using the following functions: >>> - * rte_mbuf_refcnt_update(), rte_mbuf_refcnt_read(), and >>> - * rte_mbuf_refcnt_set(). The functionality of these functions (atomic, >>> - * or non-atomic) is controlled by the >> CONFIG_RTE_MBUF_REFCNT_ATOMIC >>> - * config option. >>> - */ >>> RTE_STD_C11 >>> union { >>> - rte_atomic16_t refcnt_atomic; /**< Atomically accessed >> refcnt */ >>> - /** Non-atomically accessed refcnt */ >>> - uint16_t refcnt; >>> - }; >>> - uint16_t nb_segs; /**< Number of segments. */ >>> + /* next 8 bytes are initialised on RX descriptor rearm */ >>> + uint64_t rearm_data[1]; >> We are using zero length array as markers only and know what we are doing >> with them, >> what would you think disabling the warning instead of increasing the >> complexity >> in mbuf struct? > Okay, I will add -Wno-zero-length-bounds to the compiler toolchain flags. This would be my preference but I would like to get more input, can you please for more comments before changing the implementation in case there are some strong opinion on it?