From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail.free-electrons.com (mail.free-electrons.com [62.4.15.54]) by lists.ozlabs.org (Postfix) with ESMTP id 3zb7dR6xCqzF0sn for ; Tue, 6 Feb 2018 13:27:06 +1100 (AEDT) Date: Tue, 6 Feb 2018 03:26:46 +0100 From: Alexandre Belloni To: Stewart Smith , Michael Ellerman Cc: linuxppc-dev@lists.ozlabs.org, neelegup@linux.vnet.ibm.com, stable@vger.kernel.org Subject: Re: rtc-opal: Fix handling of firmware error codes, prevent busy loops Message-ID: <20180206022646.GP3404@piout.net> References: <1470102616-18346-1-git-send-email-stewart@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <1470102616-18346-1-git-send-email-stewart@linux.vnet.ibm.com> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Hi, On 02/08/2016 at 11:50:16 +1000, Stewart Smith wrote: > According to the OPAL docs: > https://github.com/open-power/skiboot/blob/skiboot-5.2.5/doc/opal-api/opal-rtc-read-3.txt > https://github.com/open-power/skiboot/blob/skiboot-5.2.5/doc/opal-api/opal-rtc-write-4.txt > OPAL_HARDWARE may be returned from OPAL_RTC_READ or OPAL_RTC_WRITE and this > indicates either a transient or permanent error. > > Prior to this patch, Linux was not dealing with OPAL_HARDWARE being a > permanent error particularly well, in that you could end up in a busy > loop. > > This was not too hard to trigger on an AMI BMC based OpenPOWER machine > doing a continuous "ipmitool mc reset cold" to the BMC, the result of > that being that we'd get stuck in an infinite loop in opal_get_rtc_time. > > We now retry a few times before returning the error higher up the stack. > > Cc: stable@vger.kernel.org > Signed-off-by: Stewart Smith > --- > drivers/rtc/rtc-opal.c | 12 ++++++++++-- > 1 file changed, 10 insertions(+), 2 deletions(-) > Just a note to let you know that this patch should have gone through my tree but it was not sent to linux-rtc or me. I guess what happened is that Michael cleaned up the Linux PPC patchwork queue. -- Alexandre Belloni, Bootlin (formerly Free Electrons) Embedded Linux and Kernel engineering http://bootlin.com