Re: [Linux-stable-mirror] rtc-opal: Fix handling of firmware error codes, prevent busy loops
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-r... https://github.com/open-power/skiboot/blob/skiboot-5.2.5/doc/opal-api/opal-r... 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
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 alexandre.belloni@bootlin.com writes:
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-r... https://github.com/open-power/skiboot/blob/skiboot-5.2.5/doc/opal-api/opal-r... 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
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.
Sorry, I saw it had been languishing for a long time and assumed you'd missed it.
Happy to revert/rework it if you're not happy with it.
I guess what happened is that Michael cleaned up the Linux PPC patchwork queue.
Yeah I did.
In future I'll ping you if there's something that seems to have fallen through the cracks.
cheers
On 06/02/2018 at 16:22:47 +1100, Michael Ellerman wrote:
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.
Sorry, I saw it had been languishing for a long time and assumed you'd missed it.
Happy to revert/rework it if you're not happy with it.
No, that's fine. It's just that the commit title stands out when using git log --oneline and that triggered my OCD ;)
I guess what happened is that Michael cleaned up the Linux PPC patchwork queue.
Yeah I did.
In future I'll ping you if there's something that seems to have fallen through the cracks.
Great thanks!
Alexandre Belloni alexandre.belloni@bootlin.com writes:
On 06/02/2018 at 16:22:47 +1100, Michael Ellerman wrote:
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.
Sorry, I saw it had been languishing for a long time and assumed you'd missed it.
Happy to revert/rework it if you're not happy with it.
No, that's fine. It's just that the commit title stands out when using git log --oneline and that triggered my OCD ;)
Oh no! Now I'm *really* sorry, that's the worst! :)
cheers
Alexandre Belloni alexandre.belloni@bootlin.com writes:
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-r... https://github.com/open-power/skiboot/blob/skiboot-5.2.5/doc/opal-api/opal-r... 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
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.
Apologies for not sending there. My (18 month ago self) bad.
linux-stable-mirror@lists.linaro.org
-
Alexandre Belloni -
Michael Ellerman -
Stewart Smith