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authorMing Lei <ming.lei@canonical.com>2012-06-22 14:01:40 +0400
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2012-07-17 05:04:25 +0400
commitd1c6c030fcec6f860d9bb6c632a3ebe62e28440b (patch)
tree1a6bbf92f2da6f0df73efb6725de990bb63e4853 /drivers
parent6fbfd0592ef88ba29cdce84ef92757351f1fa9c9 (diff)
downloadlinux-d1c6c030fcec6f860d9bb6c632a3ebe62e28440b.tar.xz
driver core: fix shutdown races with probe/remove(v3)
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>
Diffstat (limited to 'drivers')
-rw-r--r--drivers/base/core.c18
1 files changed, 18 insertions, 0 deletions
diff --git a/drivers/base/core.c b/drivers/base/core.c
index 846d12b5d579..65849a9aeece 100644
--- a/drivers/base/core.c
+++ b/drivers/base/core.c
@@ -1812,6 +1812,13 @@ void device_shutdown(void)
while (!list_empty(&devices_kset->list)) {
dev = list_entry(devices_kset->list.prev, struct device,
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);
/*
* 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);
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 */
pm_runtime_get_noresume(dev);
pm_runtime_barrier(dev);
@@ -1831,7 +1843,13 @@ void device_shutdown(void)
dev_dbg(dev, "shutdown\n");
dev->driver->shutdown(dev);
}
+
+ device_unlock(dev);
+ if (dev->parent)
+ device_unlock(dev->parent);
+
put_device(dev);
+ put_device(dev->parent);
spin_lock(&devices_kset->list_lock);
}