kernel-packages team mailing list archive

[Jeff Lane <jeffrey.lane@xxxxxxxxxxxxx>]

This was an issue in 2010 on Lucid.  Give that it's 2014 and I'm on
Saucy at this point, I have no idea, nor any interest in pursuing this.
:(

** Changed in: linux (Ubuntu)
       Status: Incomplete => Invalid

-- 
You received this bug notification because you are a member of Kernel
Packages, which is subscribed to linux in Ubuntu.
https://bugs.launchpad.net/bugs/571977

Title:
  [Dell Alienware M15x] Possible race condition involving rtc wakealarm
  when hibernating a system

Status in “linux” package in Ubuntu:
  Invalid

Bug description:
  I'm working on a test script that sets a time in the future in
  /sys/class/rtc/rtc0/wakealarm and then uses pm-suspend to hibernate a
  system.  I believe I've found a race condition that's causing my tests
  to fail.

  First, the steps to recreate:
  0: cat /proc/driver/rtc and verify that alarm_IRQ says 'no'
  1: echo '+180' > /sys/class/rtc/rtc0/wakealarm
  1.5: cat /proc/driver/rtc and verify that alarm_IRQ says 'yes' and the correct alarm time is set
  2: sudo pm-suspend
  3: wait 3 minutes
  4: system wakes itself
  5: wait for system to fully wake (disk activity to stop, or at the very least, keyboard and mouse function to resume on desktop)
  6: cat /proc/driver/rtc and verify that current time is > alarm time and alarm_IRQ still says 'yes'

  The test, when putting the system into an S3 state, does not suffer
  from this issue.  It DOES when I'm using S4.  I think the reason is
  that S3 wakes quickly enough that the kernel can register that the
  alarm fired and reset /proc/driver/rtc accordingly, however, when
  waking from suspend, the kernel takes far longer to wake, causing it
  to think that even though the rtc's alarm_IRQ fired the IRQ didn't
  fire, so the kernel does not reset /proc/driver/rtc.

  For example, this is the output from (my comments highlighted with ##

  # watch -n 5 'cat /proc/driver/rtc |head -5'

  ## First observation, note alarm_date is empty, this is after echoing '0' to /sys/class/rtc/rtc0/wakealarm
  rtc_time        : 20:35:11
  rtc_date        : 2010-04-29
  alrm_time       : 20:38:03
  alrm_date       : ****-**-29
  alarm_IRQ       : no
  ## wakealarm set
  rtc_time        : 20:35:16
  rtc_date        : 2010-04-29
  alrm_time       : 20:37:11
  alrm_date       : 2010-04-29
  alarm_IRQ       : yes
  ## executing pm-hibernate now
  rtc_time        : 20:35:21
  rtc_date        : 2010-04-29
  alrm_time       : 20:37:11
  alrm_date       : 2010-04-29
  alarm_IRQ       : yes
  rtc_time        : 20:35:26
  rtc_date        : 2010-04-29
  alrm_time       : 20:37:11
  alrm_date       : 2010-04-29
  alarm_IRQ       : yes
  ## System is now asleep.
  ## IRQ must be firing, because system wakes itself at this point after sleeping for the proscribed number of seconds (180)
  rtc_time        : 20:38:16
  rtc_date        : 2010-04-29
  alrm_time       : 20:37:11
  alrm_date       : 2010-04-30
  alarm_IRQ       : yes
  ## first report after system is fully awake.  Note that rtc_time is now a full 60 seconds ahead of alarm time.

  I'm not sure what's actually causing this behaviour, but what it seems
  as though the kernel isn't actually registering that the IRQ actually
  fired during a hibernate (or the rtc is broken, but it works fine
  during S3 tests and I can verify that the IRQ fires and alarm_IRQ
  resets to 'no' in S3 tests).

  In any case, a race is created that isn't met in S3 testing due to the
  nearly instantaneous kernel resumption from that sleep state, where it
  is created (or at least the race is lost) when resuming from S4 due to
  the length of time it takes to resume from that state.)

  because of this, subsequent setting of /sys/class/rtc/rtc0/wakealarm
  will fail without first clearing it with a '0' and if a piece of
  software is actually looking to see if the RTC fired it's alarm_IRQ,
  that software will believe that the IRQ has not been fired due to
  /driver/proc/rtc incorrectly reporting the event.

  ProblemType: Bug
  DistroRelease: Ubuntu 10.04
  Package: linux-image-2.6.32-21-generic 2.6.32-21.32
  Regression: No
  Reproducible: Yes
  ProcVersionSignature: Ubuntu 2.6.32-21.32-generic 2.6.32.11+drm33.2
  Uname: Linux 2.6.32-21-generic x86_64
  NonfreeKernelModules: nvidia
  AlsaVersion: Advanced Linux Sound Architecture Driver Version 1.0.21.
  AplayDevices:
   **** List of PLAYBACK Hardware Devices ****
   card 0: Intel [HDA Intel], device 0: STAC92xx Analog [STAC92xx Analog]
     Subdevices: 1/1
     Subdevice #0: subdevice #0
  Architecture: amd64
  ArecordDevices:
   **** List of CAPTURE Hardware Devices ****
   card 0: Intel [HDA Intel], device 0: STAC92xx Analog [STAC92xx Analog]
     Subdevices: 1/1
     Subdevice #0: subdevice #0
  AudioDevicesInUse:
   USER        PID ACCESS COMMAND
   /dev/snd/controlC0:  bladernr   2029 F.... pulseaudio
  CRDA: Error: [Errno 2] No such file or directory
  Card0.Amixer.info:
   Card hw:0 'Intel'/'HDA Intel at 0xf0f20000 irq 22'
     Mixer name	: 'IDT 92HD83C1X5'
     Components	: 'HDA:111d7604,102802a2,00100104'
     Controls      : 16
     Simple ctrls  : 10
  Card1.Amixer.info:
   Card hw:1 'NVidia'/'HDA NVidia at 0xcdefc000 irq 16'
     Mixer name	: 'Nvidia ID a'
     Components	: 'HDA:10de000a,10de0101,00100100'
     Controls      : 0
     Simple ctrls  : 0
  Card1.Amixer.values:
   
  Date: Thu Apr 29 20:55:42 2010
  HibernationDevice: RESUME=UUID=f4e6db09-5257-40b2-ba2a-0718fc0b3f0d
  InstallationMedia: Ubuntu 9.10 "Karmic Koala" - Release amd64 (20091027)
  MachineType: Alienware M15x
  ProcCmdLine: BOOT_IMAGE=/boot/vmlinuz-2.6.32-21-generic root=UUID=acc23352-13ab-4854-b1d7-a1099a5bf3a5 ro quiet splash
  ProcEnviron:
   LANG=en_US.UTF-8
   SHELL=/bin/bash
  RelatedPackageVersions: linux-firmware 1.34
  SourcePackage: linux
  dmi.bios.date: 03/11/2010
  dmi.bios.vendor: Alienware
  dmi.bios.version: A05
  dmi.board.vendor: Alienware
  dmi.board.version: A05
  dmi.chassis.type: 8
  dmi.chassis.vendor: Alienware
  dmi.chassis.version: A05
  dmi.modalias: dmi:bvnAlienware:bvrA05:bd03/11/2010:svnAlienware:pnM15x:pvrA05:rvnAlienware:rn:rvrA05:cvnAlienware:ct8:cvrA05:
  dmi.product.name: M15x
  dmi.product.version: A05
  dmi.sys.vendor: Alienware
  --- 
  Architecture: i386
  DistroRelease: Ubuntu 10.04
  InstallationMedia: Ubuntu 9.10 "Karmic Koala" - Release i386 (20091028.5)
  Package: linux (not installed)
  ProcEnviron:
   LANG=en_US.UTF-8
   SHELL=/bin/bash
  Tags: lucid
  Uname: Linux 2.6.34-999-generic i686
  UnreportableReason: The running kernel is not an Ubuntu kernel
  UserGroups:

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/571977/+subscriptions