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=-9.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham 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 CBD2DC4360F for ; Thu, 4 Apr 2019 09:43:48 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 92E9F20693 for ; Thu, 4 Apr 2019 09:43:48 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1554371028; bh=r8YHYRaqnoCraHtp30j9kJ1Qw0JOfqSxaEYILDaWKn0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=ChTMHEKvX8StL9FQlR7qw/V/+6MwWNrfTGWhIsa+RcOtMR9bcaoQZUk5L5XovTEa6 3xr0ATy+y7E6WLR/fM9N+ICE9OvcePRkNhsEk+AupTzxGjHbxAlT+XZCJl6sldfVa0 hIP8eUqGvi52Sy8gdrMPCGXWTZSfHrRZ9BH1/7IM= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731412AbfDDJnr (ORCPT ); Thu, 4 Apr 2019 05:43:47 -0400 Received: from mail.kernel.org ([198.145.29.99]:37148 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730145AbfDDJA1 (ORCPT ); Thu, 4 Apr 2019 05:00:27 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id BA33621741; Thu, 4 Apr 2019 09:00:25 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1554368426; bh=r8YHYRaqnoCraHtp30j9kJ1Qw0JOfqSxaEYILDaWKn0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=L7cJv/XwGkbrsoLJ9sOzXJPWcqaZNdewjfO8ip3XDZvM9S+w9Xe+MEKFLYqDkrStC ItfKf40aJJ/ilv91k1e5ey2qnYKivfZm3sB18SjsHCylWJMjAeDJ1T05/LQ9S/GpCV 19rej0j1HRT+vw1+1DMn6mss0sBTejmMjS3tFHQE= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Joe Perches , Andy Gross , David Brown , Jonathan Cameron , Hartmut Knaack , Lars-Peter Clausen , Peter Meerwald-Stadler , Linus Torvalds , Sasha Levin Subject: [PATCH 4.19 020/187] iio: adc: fix warning in Qualcomm PM8xxx HK/XOADC driver Date: Thu, 4 Apr 2019 10:45:57 +0200 Message-Id: <20190404084604.035618667@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190404084603.119654039@linuxfoundation.org> References: <20190404084603.119654039@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.19-stable review patch. If anyone has any objections, please let me know. ------------------ [ Upstream commit e0f0ae838a25464179d37f355d763f9ec139fc15 ] The pm8xxx_get_channel() implementation is unclear, and causes gcc to suddenly generate odd warnings. The trigger for the warning (at least for me) was the entirely unrelated commit 79a4e91d1bb2 ("device.h: Add __cold to dev_ logging functions"), which apparently changes gcc code generation in the caller function enough to cause this: drivers/iio/adc/qcom-pm8xxx-xoadc.c: In function ‘pm8xxx_xoadc_probe’: drivers/iio/adc/qcom-pm8xxx-xoadc.c:633:8: warning: ‘ch’ may be used uninitialized in this function [-Wmaybe-uninitialized] ret = pm8xxx_read_channel_rsv(adc, ch, AMUX_RSV4, ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ &read_nomux_rsv4, true); ~~~~~~~~~~~~~~~~~~~~~~~ drivers/iio/adc/qcom-pm8xxx-xoadc.c:426:27: note: ‘ch’ was declared here struct pm8xxx_chan_info *ch; ^~ because gcc for some reason then isn't able to see that the termination condition for the "for( )" loop in that function is also the condition for returning NULL. So it's not _actually_ uninitialized, but the function is admittedly just unnecessarily oddly written. Simplify and clarify the function, making gcc also see that it always returns a valid initialized value. Cc: Joe Perches Cc: Greg Kroah-Hartman Cc: Andy Gross Cc: David Brown Cc: Jonathan Cameron Cc: Hartmut Knaack Cc: Lars-Peter Clausen Cc: Peter Meerwald-Stadler Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin --- drivers/iio/adc/qcom-pm8xxx-xoadc.c | 10 +++------- 1 file changed, 3 insertions(+), 7 deletions(-) diff --git a/drivers/iio/adc/qcom-pm8xxx-xoadc.c b/drivers/iio/adc/qcom-pm8xxx-xoadc.c index b093ecddf1a8..54db848f0bcd 100644 --- a/drivers/iio/adc/qcom-pm8xxx-xoadc.c +++ b/drivers/iio/adc/qcom-pm8xxx-xoadc.c @@ -423,18 +423,14 @@ static irqreturn_t pm8xxx_eoc_irq(int irq, void *d) static struct pm8xxx_chan_info * pm8xxx_get_channel(struct pm8xxx_xoadc *adc, u8 chan) { - struct pm8xxx_chan_info *ch; int i; for (i = 0; i < adc->nchans; i++) { - ch = &adc->chans[i]; + struct pm8xxx_chan_info *ch = &adc->chans[i]; if (ch->hwchan->amux_channel == chan) - break; + return ch; } - if (i == adc->nchans) - return NULL; - - return ch; + return NULL; } static int pm8xxx_read_channel_rsv(struct pm8xxx_xoadc *adc, -- 2.19.1