From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: Re: [PATCH net V2] net/mlx5e: Fix a -Wmaybe-uninitialized warning Date: Mon, 16 Jan 2017 14:48:45 -0500 (EST) Message-ID: <20170116.144845.60137914620939911.davem@davemloft.net> References: <1484502646-29692-1-git-send-email-ogerlitz@mellanox.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: hadarh@mellanox.com, netdev@vger.kernel.org, arnd@arndb.de To: ogerlitz@mellanox.com Return-path: Received: from shards.monkeyblade.net ([184.105.139.130]:47544 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750865AbdAPTtX (ORCPT ); Mon, 16 Jan 2017 14:49:23 -0500 In-Reply-To: <1484502646-29692-1-git-send-email-ogerlitz@mellanox.com> Sender: netdev-owner@vger.kernel.org List-ID: From: Or Gerlitz Date: Sun, 15 Jan 2017 19:50:46 +0200 > From: Arnd Bergmann > > As found by Olof's build bot, we gain a harmless warning about a > potential uninitialized variable reference in mlx5: > > drivers/net/ethernet/mellanox/mlx5/core/en_tc.c: In function 'parse_tc_fdb_actions': > drivers/net/ethernet/mellanox/mlx5/core/en_tc.c:769:13: warning: 'out_dev' may be used uninitialized in this function [-Wmaybe-uninitialized] > drivers/net/ethernet/mellanox/mlx5/core/en_tc.c:811:21: note: 'out_dev' was declared here > > This was introduced through the addition of an 'IS_ERR/PTR_ERR' pair > that gcc is unfortunately unable to completely figure out. > > The problem being gcc cannot tell that if(IS_ERR()) in > mlx5e_route_lookup_ipv4() is equivalent to checking if(err) later, > so it assumes that 'out_dev' is used after the 'return PTR_ERR(rt)'. > > The PTR_ERR_OR_ZERO() case by comparison is fairly easy to detect > by gcc, so it can't get that wrong, so it no longer warns. > > Hadar Hen Zion already attempted to fix the warning earlier by adding fake > initializations, but that ended up not fully addressing all warnings, so > I'm reverting it now that it is no longer needed. > > Link: http://arm-soc.lixom.net/buildlogs/mainline/v4.10-rc3-98-gcff3b2c/ > Fixes: a42485eb0ee4 ("net/mlx5e: TC ipv4 tunnel encap offload error flow fixes") > Fixes: a757d108dc1a ("net/mlx5e: Fix kbuild warnings for uninitialized parameters") > Signed-off-by: Arnd Bergmann > Signed-off-by: Or Gerlitz > --- > changes from V1: > - kept calling ip_route_output_key() only when CONFIG_INET is defined Applied.