From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.0 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,T_DKIMWL_WL_HIGH, URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 89BD4C07E85 for ; Fri, 7 Dec 2018 11:46:54 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 5BC242083D for ; Fri, 7 Dec 2018 11:46:54 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="RP7O1clA"; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="UkIYXibW" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5BC242083D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender: Content-Transfer-Encoding:Content-Type:Cc:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:References:In-Reply-To: Message-ID:Subject:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=IGg1fCUP4EUkxcvOXvd+SZGvSq/Depf1maQMQvDSXZo=; b=RP7O1clAE59N1v OAjk2pFktUYgLoCAGUqlrg4nth3IcnhKERRUJITk58ItfDbt4VA+5fNHSGaoytJOA2X7KEYXHho6y S73O6Pg2YLFYHEtmi2VRu2vI/qOfzV1X9c6DLCVfuTt3bcwvVPegifNFTQCA+8hSrY9eDUqPyjdOr BsKpbqlCWzDSd5or8W+jqvlEI/3LuTETu3f/72jDNdKtHnGvjevgtfJHEVDGJOuYdMdQUjJ2IYlVb rRt2Anih2U5hwx71479EbpbG63zaZazaAHFi6BWlXIVyw/2dgSk9n4uJWN83/Swm7hktIvtuTMfyC 2yXp7YpQlknj/8kGmRGw==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.90_1 #2 (Red Hat Linux)) id 1gVEaq-0005S9-IJ; Fri, 07 Dec 2018 11:46:52 +0000 Received: from casper.infradead.org ([2001:8b0:10b:1236::1]) by bombadil.infradead.org with esmtps (Exim 4.90_1 #2 (Red Hat Linux)) id 1gVEao-00059p-DP for linux-arm-kernel@bombadil.infradead.org; Fri, 07 Dec 2018 11:46:50 +0000 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=Content-Transfer-Encoding:Content-Type: MIME-Version:References:In-Reply-To:Message-ID:Subject:Cc:To:From:Date:Sender :Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id:List-Help: List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=RACk3WKIxfiFb3nPJEon9vOh9OydMlebHN0495ebvEc=; b=UkIYXibW/ftXaH/s3+VbMQTOB9 +BQNOAAfX7vC9o+52+K/2D7/MUANu3N/i0Da7iUqLcapsc23w9trrOZJBmrjFz6TDTVTsc2RzKxBe vZa9+NTN0Qywa0hzkON8//Q7zimS87q/jgggZy0xeYYrN3ruiCW4xQ+Rv/S7q4+p1LC0mSX4vO5Dq c2OGaBaXlZWxOijTUFTjyn3BsuoVDifvw7Rtln9+tNVomDXDtQ+0j0bJ2Cgey3xQxy5Y3qxsz9nfO ys4wkj1h3BXGega7sxnoMRYiRwJnYGSzXDimMbLaCgofCUT5OjdWn4QPNqqcpu7aMx2n3L3Xdlops mYeCQbqA==; Received: from 201.86.173.17.dynamic.adsl.gvt.net.br ([201.86.173.17] helo=coco.lan) by casper.infradead.org with esmtpsa (Exim 4.90_1 #2 (Red Hat Linux)) id 1gVELg-0006KA-54; Fri, 07 Dec 2018 11:31:12 +0000 Date: Fri, 7 Dec 2018 09:31:06 -0200 From: Mauro Carvalho Chehab To: Hans Verkuil Subject: Re: [PATCH] media: cedrus: don't initialize pointers with zero Message-ID: <20181207093106.4f112d0b@coco.lan> In-Reply-To: References: X-Mailer: Claws Mail 3.16.0 (GTK+ 2.24.32; x86_64-redhat-linux-gnu) MIME-Version: 1.0 X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: devel@driverdev.osuosl.org, Maxime Ripard , Greg Kroah-Hartman , Mauro Carvalho Chehab , Paul Kocialkowski , Chen-Yu Tsai , linux-arm-kernel@lists.infradead.org, Linux Media Mailing List Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org Em Fri, 7 Dec 2018 12:14:50 +0100 Hans Verkuil escreveu: > On 12/07/2018 11:56 AM, Mauro Carvalho Chehab wrote: > > A common mistake is to assume that initializing a var with: > > struct foo f = { 0 }; > > > > Would initialize a zeroed struct. Actually, what this does is > > to initialize the first element of the struct to zero. > > > > According to C99 Standard 6.7.8.21: > > > > "If there are fewer initializers in a brace-enclosed > > list than there are elements or members of an aggregate, > > or fewer characters in a string literal used to initialize > > an array of known size than there are elements in the array, > > the remainder of the aggregate shall be initialized implicitly > > the same as objects that have static storage duration." > > > > So, in practice, it could zero the entire struct, but, if the > > first element is not an integer, it will produce warnings: > > > > drivers/staging/media/sunxi/cedrus/cedrus.c:drivers/staging/media/sunxi/cedrus/cedrus.c:78:49: warning: Using plain integer as NULL pointer > > drivers/staging/media/sunxi/cedrus/cedrus_dec.c:drivers/staging/media/sunxi/cedrus/cedrus_dec.c:29:35: warning: Using plain integer as NULL pointer > > > > A proper way to initialize it with gcc is to use: > > > > struct foo f = { }; > > > > But that seems to be a gcc extension. So, I decided to check upstream > > No, this is not a gcc extension. It's part of the latest C standard. Sure? Where the C standard spec states that? I've been seeking for such info for a while, as '= {}' is also my personal preference. I tried to build the Kernel with clang, just to be sure that this won't cause issues with the clang support, but, unfortunately, the clang compiler (not even the upstream version) is able to build the upstream Kernel yet, as it lacks asm-goto support (there is an OOT patch for llvm solving it - but it sounds too much effort for my time to have to build llvm from their sources just for a simple check like this). > It's used all over in the kernel, so please use {} instead of { NULL }. > > Personally I think {} is a fantastic invention and I wish C++ had it as > well. Fully agreed on that. > > Regards, > > Hans > > > what's the most commonly pattern. The gcc pattern has about 2000 entries: > > > > $ git grep -E "=\s*\{\s*\}"|wc -l > > 1951 > > > > The standard-C compliant pattern has about 2500 entries: > > > > $ git grep -E "=\s*\{\s*NULL\s*\}"|wc -l > > 137 > > $ git grep -E "=\s*\{\s*0\s*\}"|wc -l > > 2323 > > > > So, let's initialize those structs with: > > = { NULL } > > > > Signed-off-by: Mauro Carvalho Chehab > > --- > > drivers/staging/media/sunxi/cedrus/cedrus.c | 2 +- > > drivers/staging/media/sunxi/cedrus/cedrus_dec.c | 2 +- > > 2 files changed, 2 insertions(+), 2 deletions(-) > > > > diff --git a/drivers/staging/media/sunxi/cedrus/cedrus.c b/drivers/staging/media/sunxi/cedrus/cedrus.c > > index b538eb0321d8..44c45c687503 100644 > > --- a/drivers/staging/media/sunxi/cedrus/cedrus.c > > +++ b/drivers/staging/media/sunxi/cedrus/cedrus.c > > @@ -75,7 +75,7 @@ static int cedrus_init_ctrls(struct cedrus_dev *dev, struct cedrus_ctx *ctx) > > memset(ctx->ctrls, 0, ctrl_size); > > > > for (i = 0; i < CEDRUS_CONTROLS_COUNT; i++) { > > - struct v4l2_ctrl_config cfg = { 0 }; > > + struct v4l2_ctrl_config cfg = { NULL }; > > > > cfg.elem_size = cedrus_controls[i].elem_size; > > cfg.id = cedrus_controls[i].id; > > diff --git a/drivers/staging/media/sunxi/cedrus/cedrus_dec.c b/drivers/staging/media/sunxi/cedrus/cedrus_dec.c > > index e40180a33951..4099a42dba2d 100644 > > --- a/drivers/staging/media/sunxi/cedrus/cedrus_dec.c > > +++ b/drivers/staging/media/sunxi/cedrus/cedrus_dec.c > > @@ -26,7 +26,7 @@ void cedrus_device_run(void *priv) > > { > > struct cedrus_ctx *ctx = priv; > > struct cedrus_dev *dev = ctx->dev; > > - struct cedrus_run run = { 0 }; > > + struct cedrus_run run = { NULL }; > > struct media_request *src_req; > > unsigned long flags; > > > > > Thanks, Mauro _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel