From patchwork Fri Aug 14 09:17:30 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Victor Ding X-Patchwork-Id: 1344749 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=23.128.96.18; helo=vger.kernel.org; envelope-from=linux-rtc-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=google.com header.i=@google.com header.a=rsa-sha256 header.s=20161025 header.b=oGYgJqsY; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 4BSdBZ3wMwz9sTQ for ; Fri, 14 Aug 2020 19:17:42 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727790AbgHNJRm (ORCPT ); Fri, 14 Aug 2020 05:17:42 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46128 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726012AbgHNJRl (ORCPT ); Fri, 14 Aug 2020 05:17:41 -0400 Received: from mail-yb1-xb4a.google.com (mail-yb1-xb4a.google.com [IPv6:2607:f8b0:4864:20::b4a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 79DC8C061383 for ; Fri, 14 Aug 2020 02:17:41 -0700 (PDT) Received: by mail-yb1-xb4a.google.com with SMTP id w17so9580126ybl.9 for ; Fri, 14 Aug 2020 02:17:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=date:message-id:mime-version:subject:from:to:cc; bh=QsRsOCpoXcwdRIsVUMLGWKWsf8QgiczNEiWX1UbiUY4=; b=oGYgJqsYuUV0Hms2m3LZF+iq+NfQ6YoaeJQuq9z72NuNFa7OMslSlpLVFCZsmBJKNY ZaWg1WLV+vs/Ii/09pl7wGF+m/bB3EF5lLW7WI/pC3dVEM2c1ZuHHEsSSup17xqCh0Ec uCnsrdpI/LkrE0aBV+2tu7VnODtCWhubakNAmOVfig+qZvz/xH1E4BYlCJRCCqkq2PKD D7+5oFEyqcp7GrBssXUJh+wS72z4rB+PKi04rD25p4gCEkOgi9S3CC0BBwPFSrgw2CS8 o3D4+7jfC777vMMakgcTIm1i2mvi2D1nyoPJL9heKLuQ0bfK6llK/R6otOm3LGuJNKRJ vOgg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:message-id:mime-version:subject:from:to:cc; bh=QsRsOCpoXcwdRIsVUMLGWKWsf8QgiczNEiWX1UbiUY4=; b=DapOqDVEZwGiA2EM0iuJF+z0aw9CRD8/N6ibxYNBLUkFEKfzIMo6gSAoK9xeuOHi9o zpD24B6aGePxH/bQ5jQldOXZkSnXuH2HsrR+XdiR31k9WGPGypQqguSaa4SS+hNFl8Mw VwmkciE153jpp1IBhXtoV1On/+HBx5SardsjUVjQM0+rcDt1n72Axi24hon5H7wLNPAt GhagRk+jE7gn3UKTk5SF770WV8YpmBH9LwhLqpyqKjdvNtxTWVcD6tBQV9zM0/f3SGU0 oJJuIz75y31R/zvq8M/gYedWRdNE6oOK52lmZTaba1vCibrPVJkJ/4qYaKxIjl+nrKOk 4R+g== X-Gm-Message-State: AOAM533W/KW9YJ8m2+1FoJ3epn/JsOYxieBuP7cHqPovfdZoS9vWeoUb 7XMpk8jRCmrrUYEf6BMYlJDCyBSP/SI6ocBc X-Google-Smtp-Source: ABdhPJyqUdHa5EmOBsxJ8UelCFoy6G5Gk4fPgGTLmQMMoD2fMMoqIo1HcRzpjCoZNQJBP39oDw+oJT22mnXtWQ4J X-Received: by 2002:a25:3556:: with SMTP id c83mr2374756yba.412.1597396659823; Fri, 14 Aug 2020 02:17:39 -0700 (PDT) Date: Fri, 14 Aug 2020 19:17:30 +1000 Message-Id: <20200814191654.v2.1.Iaf7638a2f2a87ff68d85fcb8dec615e41340c97f@changeid> Mime-Version: 1.0 X-Mailer: git-send-email 2.28.0.220.ged08abb693-goog Subject: [PATCH v2] rtc: cmos: zero-init wkalrm when reading from CMOS From: Victor Ding To: LKML Cc: Alexandre Belloni , Victor Ding , Alessandro Zummo , linux-rtc@vger.kernel.org Sender: linux-rtc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-rtc@vger.kernel.org cmos_read_alarm() may leave certain fields of a struct rtc_wkalrm untouched; therefore, these fields contain garbage if not properly initialized, leading to inconsistent values when converting into time64_t. This patch to zero initialize the struct before calling cmos_read_alarm(). Note that this patch is not intended to produce a correct time64_t, it is only to produce a consistent value. In the case of suspend/resume, a correct time64_t is not necessary; a consistent value is sufficient to correctly perform an equality test for t_current_expires and t_saved_expires. Logic to deduce a correct time64_t is expensive and hence should be avoided. Signed-off-by: Victor Ding --- Changes in v2: - Initialize the struct to 0 instead of -1; - Initialize the whole struct rtc_wkalrm. drivers/rtc/rtc-cmos.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/drivers/rtc/rtc-cmos.c b/drivers/rtc/rtc-cmos.c index bcc96ab7793f..c633319cdb91 100644 --- a/drivers/rtc/rtc-cmos.c +++ b/drivers/rtc/rtc-cmos.c @@ -1006,6 +1006,7 @@ static int cmos_suspend(struct device *dev) enable_irq_wake(cmos->irq); } + memset(&cmos->saved_wkalrm, 0, sizeof(struct rtc_wkalrm)); cmos_read_alarm(dev, &cmos->saved_wkalrm); dev_dbg(dev, "suspend%s, ctrl %02x\n", @@ -1054,6 +1055,7 @@ static void cmos_check_wkalrm(struct device *dev) return; } + memset(¤t_alarm, 0, sizeof(struct rtc_wkalrm)); cmos_read_alarm(dev, ¤t_alarm); t_current_expires = rtc_tm_to_time64(¤t_alarm.time); t_saved_expires = rtc_tm_to_time64(&cmos->saved_wkalrm.time);