• Brian Norris's avatar
    PM / sleep: don't suspend parent when async child suspend_{noirq, late} fails · f7c9b17c
    Brian Norris authored
    commit 6f75c3fd upstream.
    
    Consider two devices, A and B, where B is a child of A, and B utilizes
    asynchronous suspend (it does not matter whether A is sync or async). If
    B fails to suspend_noirq() or suspend_late(), or is interrupted by a
    wakeup (pm_wakeup_pending()), then it aborts and sets the async_error
    variable. However, device A does not (immediately) check the async_error
    variable; it may continue to run its own suspend_noirq()/suspend_late()
    callback. This is bad.
    
    We can resolve this problem by doing our error and wakeup checking
    (particularly, for the async_error flag) after waiting for children to
    suspend, instead of before. This also helps align the logic for the noirq and
    late suspend cases with the logic in __device_suspend().
    
    It's easy to observe this erroneous behavior by, for example, forcing a
    device to sleep a bit in its suspend_noirq() (to ensure the parent is
    waiting for the child to complete), then return an error, and watch the
    parent suspend_noirq() still get called. (Or similarly, fake a wakeup
    event at the right (or is it wrong?) time.)
    
    Fixes: de377b39 (PM / sleep: Asynchronous threads for suspend_late)
    Fixes: 28b6fd6e (PM / sleep: Asynchronous threads for suspend_noirq)
    Reported-by: default avatarJeffy Chen <jeffy.chen@rock-chips.com>
    Signed-off-by: default avatarBrian Norris <briannorris@chromium.org>
    Signed-off-by: default avatarRafael J. Wysocki <rafael.j.wysocki@intel.com>
    Signed-off-by: default avatarBen Hutchings <ben@decadent.org.uk>
    f7c9b17c
main.c 41.8 KB