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 9EDA4A056D; Thu, 12 Mar 2020 17:47:56 +0100 (CET) Received: from [92.243.14.124] (localhost [127.0.0.1]) by dpdk.org (Postfix) with ESMTP id B24E11BFA5; Thu, 12 Mar 2020 17:47:55 +0100 (CET) Received: from mga18.intel.com (mga18.intel.com [134.134.136.126]) by dpdk.org (Postfix) with ESMTP id 73FF32BAA; Thu, 12 Mar 2020 17:47:53 +0100 (CET) X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from orsmga008.jf.intel.com ([10.7.209.65]) by orsmga106.jf.intel.com with ESMTP/TLS/DHE-RSA-AES256-GCM-SHA384; 12 Mar 2020 09:47:52 -0700 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.70,545,1574150400"; d="scan'208";a="236902285" Received: from fyigit-mobl.ger.corp.intel.com (HELO [10.251.84.123]) ([10.251.84.123]) by orsmga008.jf.intel.com with ESMTP; 12 Mar 2020 09:47:50 -0700 To: Kevin Traynor , dev@dpdk.org Cc: stable@dpdk.org, allain.legacy@windriver.com, Steven Webster , Matt Peters , "Kilheeney, Louise" References: <20200220093744.13925-1-ktraynor@redhat.com> <20200311113300.32487-1-ktraynor@redhat.com> <1e853b9f-fd91-42ef-dc0f-d834e510c6ef@intel.com> <9642a227-11db-8bb6-77cf-dca3463b4b9d@intel.com> <24e2ec05-de5d-3251-ac63-f344ec09f44e@redhat.com> From: Ferruh Yigit Autocrypt: addr=ferruh.yigit@intel.com; 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charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Subject: Re: [dpdk-dev] [PATCH v2 1/2] net/avp: fix gcc 10 maybe-uninitialized warning 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 3/12/2020 3:15 PM, Kevin Traynor wrote: > On 12/03/2020 14:31, Ferruh Yigit wrote: >> On 3/12/2020 2:18 PM, Kevin Traynor wrote: >>> On 12/03/2020 13:25, Ferruh Yigit wrote: >>>> On 3/11/2020 11:32 AM, Kevin Traynor wrote: >>>>> gcc 10.0.1 reports: >>>>> >>>>> ../drivers/net/avp/avp_ethdev.c: In function ‘avp_xmit_scattered_pkts’: >>>>> ../drivers/net/avp/avp_ethdev.c:1791:24: >>>>> warning: ‘avp_bufs[count]’ may be used uninitialized in this function [-Wmaybe-uninitialized] >>>>> 1791 | tx_bufs[i] = avp_bufs[count]; >>>>> | ~~~~~~~~^~~~~~~ >>>>> ../drivers/net/avp/avp_ethdev.c:1791:24: >>>>> warning: ‘avp_bufs[count]’ may be used uninitialized in this function [-Wmaybe-uninitialized] >>>>> >>>>> Fix by intializing the array. >>>>> >>>>> Fixes: 295abce2d25b ("net/avp: add packet transmit functions") >>>>> Cc: stable@dpdk.org >>>>> >>>>> Signed-off-by: Kevin Traynor >>>>> --- >>>>> v2: no change >>>>> >>>>> note, commit log violates line length but I didn't want to split warning msg. >>>>> >>>>> Cc: allain.legacy@windriver.com >>>>> Cc: Steven Webster >>>>> Cc: Matt Peters >>>>> --- >>>>> drivers/net/avp/avp_ethdev.c | 2 +- >>>>> 1 file changed, 1 insertion(+), 1 deletion(-) >>>>> >>>>> diff --git a/drivers/net/avp/avp_ethdev.c b/drivers/net/avp/avp_ethdev.c >>>>> index cd747b6be..1abe96ce5 100644 >>>>> --- a/drivers/net/avp/avp_ethdev.c >>>>> +++ b/drivers/net/avp/avp_ethdev.c >>>>> @@ -1695,5 +1695,5 @@ avp_xmit_scattered_pkts(void *tx_queue, >>>>> { >>>>> struct rte_avp_desc *avp_bufs[(AVP_MAX_TX_BURST * >>>>> - RTE_AVP_MAX_MBUF_SEGMENTS)]; >>>>> + RTE_AVP_MAX_MBUF_SEGMENTS)] = {}; >>>>> struct avp_queue *txq = (struct avp_queue *)tx_queue; >>>>> struct rte_avp_desc *tx_bufs[AVP_MAX_TX_BURST]; >>>>> >>>> >>>> Isn't this a false positive, can there be any case 'avp_bufs[]' used >>>> uninitialized? Or am I missing something. >>>> >>> >>> I presume it's because it's not being initialized in the fn and there is >>> some paths in fn's it's passed to that don't initialize it. Of course in >>> practice with "normal" values this might not happen. >> >> 'avp_fifo_get(alloc_q, (void **)&avp_bufs, segments);' initializes it, and I am >> not just talking about 'normal' case, I don't see any case that 'avp_bufs[]' >> used uninitialized, can you see any? >> > > Well, it's initialization there is dependent on not hitting the first > return and the loop executing. If whole array not initialized, the next line, 'if (unlikely(n != segments))', will catch it and function return without using 'avp_bufs[]' at all. Anyway, as I said I can't see a case that 'avp_bufs[]' used uninitialized, and not sure about additional zeroing out in datapath function if this is a false positive, but if windriver guys are OK I won't object. > >>> >>>> If this is false positive, does it worth to report to issue to gcc? >>>> >>> >> >