From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754143Ab3KCSB0 (ORCPT ); Sun, 3 Nov 2013 13:01:26 -0500 Received: from mo6.mail-out.ovh.net ([178.32.228.6]:43997 "EHLO mo6.mail-out.ovh.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753723Ab3KCSBU (ORCPT ); Sun, 3 Nov 2013 13:01:20 -0500 From: Boris BREZILLON To: Wim Van Sebroeck Cc: Fabio Porcedda , Nicolas Ferre , Guenter Roeck , Yang Wenyou , linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, linux-watchdog@vger.kernel.org, Boris BREZILLON Subject: [PATCH 3/3] watchdog: at91sam9_wdt: increase security margin on watchdog counter reset Date: Sun, 3 Nov 2013 18:52:44 +0100 Message-Id: <1383501164-8111-4-git-send-email-b.brezillon@overkiz.com> X-Mailer: git-send-email 1.7.9.5 In-Reply-To: <1383501164-8111-1-git-send-email-b.brezillon@overkiz.com> References: <1383501164-8111-1-git-send-email-b.brezillon@overkiz.com> X-Ovh-Tracer-Id: 10214726905154795707 X-Ovh-Remote: 78.236.240.82 (cha74-5-78-236-240-82.fbx.proxad.net) X-Ovh-Local: 213.186.33.20 (ns0.ovh.net) X-OVH-SPAMSTATE: OK X-OVH-SPAMSCORE: -100 X-OVH-SPAMCAUSE: gggruggvucftvghtrhhoucdtuddrfeeiledrhedvucetufdoteggodetrfcurfhrohhfihhlvgemucfqggfjnecuuegrihhlohhuthemuceftddtnecusecvtfgvtghiphhivghnthhsucdlqddutddtmd X-Spam-Check: DONE|U 0.5/N X-VR-SPAMSTATE: OK X-VR-SPAMSCORE: -100 X-VR-SPAMCAUSE: gggruggvucftvghtrhhoucdtuddrfeeiledrhedvucetufdoteggodetrfcurfhrohhfihhlvgemucfqggfjnecuuegrihhlohhuthemuceftddtnecusecvtfgvtghiphhivghnthhsucdlqddutddtmd Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Try to reset the watchdog counter 4 or 2 times more often than actually requested, to avoid spurious watchdog reset. If this is not possible because of the min_heartbeat value, reset it at the min_heartbeat period. Signed-off-by: Boris BREZILLON --- drivers/watchdog/at91sam9_wdt.c | 25 ++++++++++++++++--------- 1 file changed, 16 insertions(+), 9 deletions(-) diff --git a/drivers/watchdog/at91sam9_wdt.c b/drivers/watchdog/at91sam9_wdt.c index ab0c4e0..489729b 100644 --- a/drivers/watchdog/at91sam9_wdt.c +++ b/drivers/watchdog/at91sam9_wdt.c @@ -158,6 +158,7 @@ static int at91_wdt_init(struct platform_device *pdev, struct at91wdt *wdt) int err; u32 mask = wdt->mr_mask; unsigned long min_heartbeat = 1; + unsigned long max_heartbeat; struct device *dev = &pdev->dev; tmp = wdt_read(wdt, AT91_WDT_MR); @@ -181,23 +182,29 @@ static int at91_wdt_init(struct platform_device *pdev, struct at91wdt *wdt) if (delta < value) min_heartbeat = ticks_to_hz_roundup(value - delta); - wdt->heartbeat = ticks_to_hz_rounddown(value); - if (!wdt->heartbeat) { + max_heartbeat = ticks_to_hz_rounddown(value); + if (!max_heartbeat) { dev_err(dev, "heartbeat is too small for the system to handle it correctly\n"); return -EINVAL; } - if (wdt->heartbeat < min_heartbeat + 4) { + /* + * Try to reset the watchdog counter 4 or 2 times more often than + * actually requested, to avoid spurious watchdog reset. + * If this is not possible because of the min_heartbeat value, reset + * it at the min_heartbeat period. + */ + if ((max_heartbeat / 4) >= min_heartbeat) + wdt->heartbeat = max_heartbeat / 4; + else if ((max_heartbeat / 2) >= min_heartbeat) + wdt->heartbeat = max_heartbeat / 2; + else wdt->heartbeat = min_heartbeat; + + if (max_heartbeat < min_heartbeat + 4) dev_warn(dev, "min heartbeat and max heartbeat might be too close for the system to handle it correctly\n"); - if (wdt->heartbeat < 4) - dev_warn(dev, - "heartbeat might be too small for the system to handle it correctly\n"); - } else { - wdt->heartbeat -= 4; - } if ((tmp & AT91_WDT_WDFIEN) && wdt->irq) { err = request_irq(wdt->irq, wdt_interrupt, -- 1.7.9.5