drivers/rtc: fix rcu unexpected reboot#592
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Why needed (PROBLEM): Under 'chrony' configuration or/and further hwrtc change the RCU on the rtc_timer_do_work() reported and reproduced. Easy reproduced on armhf Nokia-AC3X. Not reproduced on SONiC TRIXIE. How fixed: drivers/rtc/interface.c: rtc_timer_do_work() When processing expired RTC events and rearming them, use "now" instead of "expiry" to prevent endless loops. Signed-off-by: Elad Nachman <enachman@marvell.com> Signed-off-by: Yan Markman <ymarkman@marvell.com>
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Please also send this upstream for review.
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| When processing expired RTC events and rearming them, use now | ||
| instead of expiry to prevent endless loops. | ||
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Please add a Fixes: tag, and also list the devices in the commit message.
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| + if (rtc && rtc->ops && rtc->ops->read_time) { | ||
| + if (!rtc->ops->read_time(rtc->dev.parent, &new_tm)) { | ||
| + pr_err("new rtc tm %d %d %d %d %d %d %d %d %d\n", |
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Please re-write. Currently it’s more like a debug message. (Which is good to have.)
| /* Re-add/fwd periodic timers */ | ||
| if (ktime_to_ns(timer->period)) { | ||
| - timer->node.expires = ktime_add(timer->node.expires, | ||
| + timer->node.expires = ktime_add(now/*timer->node.expires*/, |
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We have git, so commenting this out is not useful.
sonic-net/sonic-linux-kernel#592 Signed-off-by: Yan Markman <ymarkman@marvell.com>
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HI @paulmenzel |
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I'm inclined to agree with the comments on the mailing list. What is special about your hardware that common code needs to be changed here? |
The HW is not special, the test added that changes the clock back and forth constantly is special, and apparently no other SONIC HW uses RTC as the main clock. |
No. I have done RTC time jumps back and forth on other hardware running SONiC. None of them leads to an expected reboot. |
The question is whether those HW's RTC support PIE/UIE, whether it was enabled and rtc_timer_do_work() was actually called. Can you list these HW it was tested on, plus link to a HW diagram of the board and SOC, and finally a link to the dts or for x86_64 lspci -k ? Thanks... |
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Why needed (PROBLEM):
Under 'chrony' configuration or/and further hwrtc change the RCU on the rtc_timer_do_work() reported and reproduced.
How fixed:
drivers/rtc/interface.c: rtc_timer_do_work()
When processing expired RTC events and rearming them, use "now"
instead of "expiry" to prevent endless loops.