From mboxrd@z Thu Jan 1 00:00:00 1970 From: Zoltan Kiss Subject: Re: [PATCH v2] mempool: adjust name string size in related data types Date: Thu, 21 Jul 2016 14:47:48 +0100 Message-ID: <34eb5f3b-307a-3072-d262-e46a6437eea7@linaro.org> References: <1469034999-2732-1-git-send-email-zoltan.kiss@schaman.hu> Mime-Version: 1.0 Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Cc: Bruce Richardson To: Olivier Matz , Zoltan Kiss , dev@dpdk.org Return-path: Received: from mail-lf0-f50.google.com (mail-lf0-f50.google.com [209.85.215.50]) by dpdk.org (Postfix) with ESMTP id 03BB347D1 for ; Thu, 21 Jul 2016 15:47:51 +0200 (CEST) Received: by mail-lf0-f50.google.com with SMTP id g62so62431224lfe.3 for ; Thu, 21 Jul 2016 06:47:50 -0700 (PDT) In-Reply-To: List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" On 21/07/16 14:40, Olivier Matz wrote: > Hi Zoltan, > > > On 07/20/2016 07:16 PM, Zoltan Kiss wrote: >> A recent patch brought up an issue about the size of the 'name' fields: >> >> 85cf0079 mem: avoid memzone/mempool/ring name truncation >> >> These relations should be observed: >> >> 1. Each ring creates a memzone with a prefixed name: >> RTE_RING_NAMESIZE <= RTE_MEMZONE_NAMESIZE - strlen(RTE_RING_MZ_PREFIX) >> >> 2. There are some mempool handlers which create a ring with a prefixed >> name: >> RTE_MEMPOOL_NAMESIZE <= RTE_RING_NAMESIZE - strlen(RTE_MEMPOOL_MZ_PREFIX) >> >> 3. A mempool can create up to RTE_MAX_MEMZONE pre and postfixed memzones: >> sprintf(postfix, "_%d", RTE_MAX_MEMZONE) >> RTE_MEMPOOL_NAMESIZE <= RTE_MEMZONE_NAMESIZE - >> strlen(RTE_MEMPOOL_MZ_PREFIX) - strlen(postfix) >> >> Setting all of them to 32 hides this restriction from the application. >> This patch decreases the mempool and ring string size to accommodate for >> these prefixes, but it doesn't apply the 3rd constraint. Applications >> relying on these constants need to be recompiled, otherwise they'll run >> into ENAMETOOLONG issues. >> The size of the arrays are kept 32 for ABI compatibility, it can be >> decreased next time the ABI changes. >> >> Signed-off-by: Zoltan Kiss > > Looks like to be a good compromise for the 16.07 release. One question > however: why not taking in account the 3rd constraint? Because it may > not completly fix the issue if the mempool is fragmented. > > We could define RTE_MEMPOOL_NAMESIZE to 24 > = 32 - len('mp_') - len('_0123')) I was trying to figure out a compile time macro for strlen(postfix), but I could not. Your suggestion would work only until someone increases RTE_MAX_MEMZONE above 9999. As the likelihood of fragmenting a pool over 99 memzones seems small, I did not bother to fix this with an ugly hack, but if you think we should include it, let me know! > > Thanks, > Olivier >