1. 23 Oct, 2010 1 commit
    • Rafael J. Wysocki's avatar
      ACPI / PM: Fix reference counting of power resources · 3e384ee6
      Rafael J. Wysocki authored
      The reference counting of ACPI power resources is currently broken
      for a few reasons.  First, instead of using a simple reference
      counter per power resource it uses a list of objects representing
      refereces to the given power resource from devices.  This leads to
      the second breakage, because it prevents power resources from
      being referenced more than once by one device, which is necessary
      if the device is configured to signal wakeup.  Namely, when putting
      the device into a low power state we first call
      acpi_enable_wakeup_device_power() that should reference count power
      resources needed for signaling wakeup and then we call
      acpi_power_transition() to power off the device.  The latter call
      drops references to the device's power resources, possibly including
      the ones added by acpi_enable_wakeup_device_power(), so the device
      can't signal wakeup as a result.  Apart from this, the locking
      in acpi_power_on() and acpi_power_off_device() doesn't prevent
      all possible races from happening, which may be problematic for
      runtime PM and asynchronous suspend and resume.
      
      Fix the problem by using a counter for power resources reference
      counting and putting the evaluation of ACPI _ON and _OFF methods
      under the power resource mutex.
      Reported-by: default avatarMatthew Garrett <mjg@redhat.com>
      Signed-off-by: default avatarRafael J. Wysocki <rjw@sisk.pl>
      Signed-off-by: default avatarLen Brown <len.brown@intel.com>
      3e384ee6
  2. 20 Oct, 2010 5 commits
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  7. 15 Oct, 2010 1 commit