Driver core: Protect device shutdown from hot unplug events.
While device_shutdown() walks through devices_kset to shutdown all devices, device unplug events may race to shutdown individual devices. Specifically, sd_shutdown(), on behalf of fc_starget_delete(), has been observed deleting devices during device_shutdown()'s list traversal. So we factor out list_for_each_entry_safe_reverse(...) in favor of while (!list_empty(...)). Signed-off-by: Hugh Daschbach <hdasch@broadcom.com> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
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@ -1734,10 +1734,25 @@ EXPORT_SYMBOL_GPL(device_move);
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*/
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void device_shutdown(void)
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{
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struct device *dev, *devn;
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struct device *dev;
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spin_lock(&devices_kset->list_lock);
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/*
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* Walk the devices list backward, shutting down each in turn.
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* Beware that device unplug events may also start pulling
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* devices offline, even as the system is shutting down.
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*/
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while (!list_empty(&devices_kset->list)) {
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dev = list_entry(devices_kset->list.prev, struct device,
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kobj.entry);
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get_device(dev);
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/*
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* Make sure the device is off the kset list, in the
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* event that dev->*->shutdown() doesn't remove it.
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*/
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list_del_init(&dev->kobj.entry);
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spin_unlock(&devices_kset->list_lock);
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list_for_each_entry_safe_reverse(dev, devn, &devices_kset->list,
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kobj.entry) {
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if (dev->bus && dev->bus->shutdown) {
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dev_dbg(dev, "shutdown\n");
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dev->bus->shutdown(dev);
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@ -1745,6 +1760,10 @@ void device_shutdown(void)
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dev_dbg(dev, "shutdown\n");
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dev->driver->shutdown(dev);
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}
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put_device(dev);
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spin_lock(&devices_kset->list_lock);
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}
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spin_unlock(&devices_kset->list_lock);
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async_synchronize_full();
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}
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