1. 17 Feb, 2013 1 commit
    • Heiko Carstens's avatar
      s390/timer: avoid overflow when programming clock comparator · 18051b42
      Heiko Carstens authored
      commit d911e03d upstream.
      
      Since ed4f2094 "s390/time: fix sched_clock() overflow" a new helper function
      is used to avoid overflows when converting TOD format values to nanosecond
      values.
      The kvm interrupt code formerly however only worked by accident because of
      an overflow. It tried to program a timer that would expire in more than ~29
      years. Because of the old TOD-to-nanoseconds overflow bug the real expiry
      value however was much smaller, but now it isn't anymore.
      This however triggers yet another bug in the function that programs the clock
      comparator s390_next_ktime(): if the absolute "expires" value is after 2042
      this will result in an overflow and the programmed value is lower than the
      current TOD value which immediatly triggers a clock comparator (= timer)
      interrupt.
      Since the timer isn't expired it will be programmed immediately again and so
      on... the result is a dead system.
      To fix this simply program the maximum possible value if an overflow is
      detected.
      Reported-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
      Tested-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
      Signed-off-by: default avatarHeiko Carstens <heiko.carstens@de.ibm.com>
      Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
      18051b42
  2. 14 Feb, 2013 37 commits
  3. 11 Feb, 2013 2 commits