lkml.org 
[lkml]   [2008]   [Jan]   [5]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    From
    SubjectRe: [PATCH] PM: Acquire device locks on suspend
    Date
    On Saturday, 5 of January 2008, Alan Stern wrote:
    > On Sat, 5 Jan 2008, Rafael J. Wysocki wrote:
    >
    > > Greg, Andrew,
    > >
    > > The appended patch is a replacement for
    > > gregkh-driver-pm-acquire-device-locks-prior-to-suspending.patch that deadlocked
    > > suspend and hibernation on some systems.
    > >
    > > Please consider for applying.
    >
    > This warning message:
    >
    > > @@ -905,6 +915,13 @@ void device_del(struct device * dev)
    > > struct device * parent = dev->parent;
    > > struct class_interface *class_intf;
    > >
    > > + if (pm_sleep_lock()) {
    > > + dev_warn(dev, "Illegal %s during suspend\n", __FUNCTION__);
    > > + dump_stack();
    > > + } else {
    >
    > will unavoidably be triggered by this code:

    Ah, my fault, sorry.

    > > +void device_pm_destroy_suspended(struct device *dev)
    > > +{
    > > + pr_debug("PM: Removing suspended device %s:%s\n",
    > > + dev->bus ? dev->bus->name : "No Bus",
    > > + kobject_name(&dev->kobj));
    > > + mutex_lock(&dpm_list_mtx);
    > > + list_del_init(&dev->power.entry);
    > > + mutex_unlock(&dpm_list_mtx);
    > > + up(&dev->sem);
    > > + device_unregister(dev);
    > > +}
    >
    > since the call to device_del() will occur while the pm_sleep_rwsem is
    > still locked for writing. That's why I suggested not unregistering
    > these devices until after everything else has been resumed and the
    > rwsem has been dropped.

    Hmm, well. I'll go back to the previous version, then. Sorry for the mess.

    > Another thing to watch out for: Just in case somebody ends up calling
    > destroy_suspended_device(dev) from within dev's own resume method, you
    > should interchange the resume_device() and the list_move_tail()
    > calls in dpm_resume().

    However, if we unregister them all at once after releasing pm_sleep_rwsem,
    that shouldn't be necessary, right?

    Rafael


    \
     
     \ /
      Last update: 2008-01-05 21:21    [W:0.024 / U:61.260 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site