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driver core: fix shutdown races with probe/remove(v3)

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Firstly, .shutdown callback may touch a uninitialized hardware
if dev->driver is set and .probe is not completed.

Secondly, device_shutdown() may dereference a null pointer to cause
oops when dev->driver is cleared after it has been checked in
device_shutdown().

So just hold device lock and its parent lock(if it has) to
fix the races.

Cc: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Ming Lei <ming.lei@canonical.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Ming Lei
2012-06-22 18:01:40 +08:00
committed by Greg Kroah-Hartman
parent 6fbfd0592e
commit d1c6c030fc
1 changed files with 18 additions and 0 deletions
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18
drivers/base/core.c
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@@ -1812,6 +1812,13 @@ void device_shutdown(void)
while (!list_empty(&devices_kset->list)) { while (!list_empty(&devices_kset->list)) {
dev = list_entry(devices_kset->list.prev, struct device, dev = list_entry(devices_kset->list.prev, struct device,
kobj.entry); kobj.entry);
/*
* hold reference count of device's parent to
* prevent it from being freed because parent's
* lock is to be held
*/
get_device(dev->parent);
get_device(dev); get_device(dev);
/* /*
* Make sure the device is off the kset list, in the * Make sure the device is off the kset list, in the
@@ -1820,6 +1827,11 @@ void device_shutdown(void)
list_del_init(&dev->kobj.entry); list_del_init(&dev->kobj.entry);
spin_unlock(&devices_kset->list_lock); spin_unlock(&devices_kset->list_lock);
/* hold lock to avoid race with probe/release */
if (dev->parent)
device_lock(dev->parent);
device_lock(dev);
/* Don't allow any more runtime suspends */ /* Don't allow any more runtime suspends */
pm_runtime_get_noresume(dev); pm_runtime_get_noresume(dev);
pm_runtime_barrier(dev); pm_runtime_barrier(dev);
@@ -1831,7 +1843,13 @@ void device_shutdown(void)
dev_dbg(dev, "shutdown\n"); dev_dbg(dev, "shutdown\n");
dev->driver->shutdown(dev); dev->driver->shutdown(dev);
} }
device_unlock(dev);
if (dev->parent)
device_unlock(dev->parent);
put_device(dev); put_device(dev);
put_device(dev->parent);
spin_lock(&devices_kset->list_lock); spin_lock(&devices_kset->list_lock);
} }