From: Michael Ellerman <patch-notifications@ellerman.id.au>
To: Stewart Smith <stewart@linux.vnet.ibm.com>,
linuxppc-dev@lists.ozlabs.org
Cc: neelegup@linux.vnet.ibm.com,
Stewart Smith <stewart@linux.vnet.ibm.com>,
stable@vger.kernel.org
Subject: Re: rtc-opal: Fix handling of firmware error codes, prevent busy loops
Date: Mon, 29 Jan 2018 15:13:44 +1100 (AEDT) [thread overview]
Message-ID: <3zVGN90phWz9s83@ozlabs.org> (raw)
In-Reply-To: <1470102616-18346-1-git-send-email-stewart@linux.vnet.ibm.com>
On Tue, 2016-08-02 at 01:50:16 UTC, 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 <stewart@linux.vnet.ibm.com>
Applied to powerpc next, thanks.
https://git.kernel.org/powerpc/c/5b8b58063029f02da573120ef4dc90
cheers
next prev parent reply other threads:[~2018-01-29 4:13 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-08-02 1:50 [PATCH] rtc-opal: Fix handling of firmware error codes, prevent busy loops Stewart Smith
2016-08-03 7:12 ` Michael Ellerman
2018-01-29 4:13 ` Michael Ellerman [this message]
2018-02-06 2:26 ` Alexandre Belloni
2018-02-06 5:22 ` Michael Ellerman
2018-02-06 12:42 ` Alexandre Belloni
2018-02-06 14:06 ` Michael Ellerman
2018-02-06 7:57 ` Stewart Smith
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