From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751862AbbEHBrW (ORCPT ); Thu, 7 May 2015 21:47:22 -0400 Received: from bh-25.webhostbox.net ([208.91.199.152]:43383 "EHLO bh-25.webhostbox.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751253AbbEHBrU (ORCPT ); Thu, 7 May 2015 21:47:20 -0400 Message-ID: <554C15A5.2040300@roeck-us.net> Date: Thu, 07 May 2015 18:47:17 -0700 From: Guenter Roeck User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:31.0) Gecko/20100101 Thunderbird/31.6.0 MIME-Version: 1.0 To: Doug Anderson , wim@iguana.be CC: jszhang@marvell.com, linux-watchdog@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1/2] watchdog: dw_wdt: Use a mutex, not a spinlock References: <1431036564-4189-1-git-send-email-dianders@chromium.org> In-Reply-To: <1431036564-4189-1-git-send-email-dianders@chromium.org> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit X-Authenticated_sender: linux@roeck-us.net X-OutGoing-Spam-Status: No, score=-1.0 X-CTCH-PVer: 0000001 X-CTCH-Spam: Unknown X-CTCH-VOD: Unknown X-CTCH-Flags: 0 X-CTCH-RefID: str=0001.0A020201.554C15A7.00FD,ss=1,re=0.000,recu=0.000,reip=0.000,cl=1,cld=1,fgs=0 X-CTCH-Score: 0.000 X-CTCH-ScoreCust: 0.000 X-CTCH-Rules: X-CTCH-SenderID: linux@roeck-us.net X-CTCH-SenderID-Flags: 0 X-CTCH-SenderID-TotalMessages: 2 X-CTCH-SenderID-TotalSpam: 0 X-CTCH-SenderID-TotalSuspected: 0 X-CTCH-SenderID-TotalConfirmed: 0 X-CTCH-SenderID-TotalBulk: 0 X-CTCH-SenderID-TotalVirus: 0 X-CTCH-SenderID-TotalRecipients: 0 X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - bh-25.webhostbox.net X-AntiAbuse: Original Domain - vger.kernel.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - roeck-us.net X-Get-Message-Sender-Via: bh-25.webhostbox.net: mailgid no entry from get_relayhosts_entry X-Source: X-Source-Args: X-Source-Dir: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/07/2015 03:09 PM, Doug Anderson wrote: > Right now the dw_wdt uses a spinlock to protect dw_wdt_open(). The > problem is that while holding the spinlock we call: > -> dw_wdt_set_top() > -> dw_wdt_top_in_seconds() > -> clk_get_rate() > -> clk_prepare_lock() > -> mutex_lock() > > Locking a mutex while holding a spinlock is not allowed and leads to > warnings like "BUG: spinlock wrong CPU on CPU#1", among other > problems. > > There's no reason to use a spinlock, so switch to a mutex. > > Signed-off-by: Doug Anderson Reviewed-by: Guenter Roeck