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 08933A046B; Thu, 9 Jan 2020 15:29:13 +0100 (CET) Received: from [92.243.14.124] (localhost [127.0.0.1]) by dpdk.org (Postfix) with ESMTP id D084C1DE2F; Thu, 9 Jan 2020 15:29:12 +0100 (CET) Received: from mga09.intel.com (mga09.intel.com [134.134.136.24]) by dpdk.org (Postfix) with ESMTP id 2144F1DE1D; Thu, 9 Jan 2020 15:29:10 +0100 (CET) X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga005.jf.intel.com ([10.7.209.41]) by orsmga102.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 09 Jan 2020 06:29:10 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.69,414,1571727600"; d="scan'208";a="396105734" Received: from aburakov-mobl1.ger.corp.intel.com (HELO [10.237.220.107]) ([10.237.220.107]) by orsmga005.jf.intel.com with ESMTP; 09 Jan 2020 06:29:09 -0800 To: Olivier Matz Cc: dev@dpdk.org, Andrew Rybchenko , stable@dpdk.org References: <20200109132720.15664-1-olivier.matz@6wind.com> <8b59b3c9-ac1a-f448-e38d-063a6cb8ba7a@intel.com> <20200109142351.GJ22738@platinum> From: "Burakov, Anatoly" Message-ID: <6e43ec20-4fa5-55fa-6ca9-2ffca9bcf7dc@intel.com> Date: Thu, 9 Jan 2020 14:29:08 +0000 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.3.1 MIME-Version: 1.0 In-Reply-To: <20200109142351.GJ22738@platinum> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Subject: Re: [dpdk-dev] [PATCH] mempool: fix mempool virt populate with small chunks X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" On 09-Jan-20 2:23 PM, Olivier Matz wrote: > On Thu, Jan 09, 2020 at 01:52:41PM +0000, Burakov, Anatoly wrote: >> On 09-Jan-20 1:27 PM, Olivier Matz wrote: >>> To populate a mempool with a virtual area, the mempool code calls >>> rte_mempool_populate_iova() for each iova-contiguous area. It happens >>> (rarely) that this area is too small to store one object. In this case, >>> rte_mempool_populate_iova() returns an error, which is forwarded by >>> rte_mempool_populate_virt(). >>> >>> This case should not throw an error in >>> rte_mempool_populate_virt(). Instead, the area that is too small should >>> just be ignored. >>> >>> To fix this issue, change the return value of >>> rte_mempool_populate_iova() to -ENOBUFS when no object can be populated, >>> so it can be ignored by the caller. As this would be an API change, add >>> a compat wrapper to keep the current API unchanged. The wrapper will be >>> removed for 20.11. >>> >>> Fixes: 354788b60cfd ("mempool: allow populating with unaligned virtual area") >>> Cc: stable@dpdk.org >>> >>> Signed-off-by: Olivier Matz >>> --- >>> >> >> The approach fixes the issue on my end, so >> >> Tested-by: Anatoly Burakov >> >>> Is there a simple way to ensure that we won't forget to remove the >>> wrapper for 20.11? Anatoly suggested me to use versioned symbols, but >>> it's not clear to me how. >>> >> >> Yes, i'd like to do better than "ah shur we won't forget pinky swear". >> >> Can't we do this with ABI versioning? E.g. >> >> rte_populate_iova_v20() ... returns EINVAL >> >> rte_populate_iova_v21() ... returns ENOBUFS >> >> I'm pretty sure, even if it doesn't break, it will still be more likely to >> not be forgotten because there's almost a guarantee that someone will grep >> for symbol versioning macros across the codebase around 20.11 timeframe. > > Without using symbol versionning, would this be ok too? > > int > rte_mempool_populate_iova(struct rte_mempool *mp, char *vaddr, > rte_iova_t iova, size_t len, rte_mempool_memchunk_free_cb_t *free_cb, > void *opaque) > { > int ret; > > ret = __rte_mempool_populate_iova(mp, vaddr, iova, len, free_cb, opaque); > > #if RTE_VERSION < RTE_VERSION_NUM(20, 11, 0, 0) > if (ret == -ENOBUFS) > ret = -EINVAL; > #endif > > return ret; > } > > Well it would certainly work :) it just makes it more likely that this will be missed. How about, we leave your patch as is, and then you submit another patch marked for [20.11] and mark it as Deferred straight away? This is probably the best method to not forget that i can think of, if you're so averse to symbol versioning :D > >> -- >> Thanks, >> Anatoly -- Thanks, Anatoly