linux-kernel - Re: [REGRESSION] rtc/interface.c: kills suspend-to-ram

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Tue, 17 Apr 2012 16:11:32 -0400
From:	Mark Lord <kernel@...savvy.com>
To:	John Stultz <john.stultz@...aro.org>
CC:	richard -rw- weinberger <richard.weinberger@...il.com>,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	rtc-linux@...glegroups.com,
	Alessandro Zummo <a.zummo@...ertech.it>,
	Greg Kroah-Hartman <greg@...ah.com>, stable@...r.kernel.org,
	Rabin Vincent <rabin.vincent@...ricsson.com>
Subject: Re: [REGRESSION] rtc/interface.c: kills suspend-to-ram

On 12-04-17 01:13 AM, John Stultz wrote:
..
> -    rtc->ops->alarm_irq_enable(rtc->dev.parent, false);
> +    //rtc->ops->alarm_irq_enable(rtc->dev.parent, false);
> +    dump_stack();
..

Okay, the call into here is coming from a "hwclock -w -u" line
in the system suspend script.

Since that command isn't touching the hardware Alarm,
then neither should the Linux kernel.  Yet it is touching it.

>      CMOS_WRITE(rtc_control, RTC_CONTROL);
> -    hpet_mask_rtc_irq_bit(mask);
> +    //hpet_mask_rtc_irq_bit(mask);
> 
> -    cmos_checkintr(cmos, rtc_control);
> +    //cmos_checkintr(cmos, rtc_control); 
...

The problem still occurs (lockup on suspend)
with both lines above commented out.

Note that it's not 100% in any case, more like 8/10,
indicating a possible strong race condition somewhere.

I think all that should be done here, is to change the kernel
to NOT enable/disable the Alarm unless told to do so by
an explicit userspace action.  Eg. writing to /sys/../wakealarm
and/or /proc/acpi/alarm.

If userspace leaves the alarm alone, then so should the kernel when possible.
That's the old behaviour before the new alarm_irq_enable() stuff.

Cheers
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/