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[31.172.191.173]) by smtp.gmail.com with ESMTPSA id e27sm8121069lfb.79.2019.11.04.06.06.01 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 04 Nov 2019 06:06:01 -0800 (PST) To: "Xing, Beilei" , "dev@dpdk.org" , "Zhang, Qi Z" Cc: "mattias.ronnblom@ericsson.com" , "stephen@networkplumber.org" References: <20191028142145.3758-1-aostruszka@marvell.com> <20191029141212.4907-1-aostruszka@marvell.com> <20191029141212.4907-11-aostruszka@marvell.com> <94479800C636CB44BD422CB454846E013CE7E959@SHSMSX101.ccr.corp.intel.com> From: Andrzej Ostruszka Message-ID: Date: Mon, 4 Nov 2019 15:06:01 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.9.0 MIME-Version: 1.0 In-Reply-To: <94479800C636CB44BD422CB454846E013CE7E959@SHSMSX101.ccr.corp.intel.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Subject: Re: [dpdk-dev] [PATCH v6 10/12] net/i40e: clean LTO build warnings (maybe-uninitialized) 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" Beilei Thank you for the comment, please see below. On 11/1/19 3:05 AM, Xing, Beilei wrote: >> -----Original Message----- >> From: Andrzej Ostruszka [mailto:aostruszka@marvell.com] [...] >> Subject: [PATCH v6 10/12] net/i40e: clean LTO build warnings (maybe- >> uninitialized) >> >> During LTO build compiler reports some 'false positive' warnings about >> variables being possibly used uninitialized. This patch silences these warnings. >> >> Exemplary compiler warning to suppress (with LTO enabled): >> error: ‘filter_idx’ may be used uninitialized in this function [-Werror=maybe- >> uninitialized] >> PMD_DRV_LOG(INFO, "Added port %d with AQ command with index %d", > > Hi, > > Thanks for the patch. Please also add fix line here and Cc stable. Are you saying that there is actually a problem in the code? IMHO the code is fine and this patch just prevents gcc from issuing a false warning. What I think is going on is that gcc looks into i40e_aq_add_udp_tunnel() and sees that filter_idx is updated under condition "if (!status ..." and figures out that if status is positive then filter_idx could be used uninitialized because in the calling function we test "if (ret < 0)". However it fails to take into account the actual enum definition (only non-positive values) and the implementation of i40e_asq_send_command(). So, if this is only work-around for the gcc deficiency, then I would prefer to not add any fixline and to not pull that patch into stable. Please let me know what you think. Regards Andrzej