mtd: avoid registering reboot notifier twice

Calling mtd_device_parse_register with the same mtd_info
(e.g. registering several partitions on a single device)
would add the same reboot notifier twice, causing an
infinte loop in notifier_chain_register during boot up.

Signed-off-by: Niklas Cassel <nks@flawful.org>
[Brian: add FIXME comments]
Signed-off-by: Brian Norris <computersforpeace@gmail.com>
Signed-off-by: Brian Norris <computersforpeace@gmail.com>

diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c
index cbc0fc46d2d6eb172b85f306453ab42527acb4cb..52eea932c312b7466a8d2632bd993f609f15fa17 100644 (file)
--- a/drivers/mtd/mtdcore.c
+++ b/drivers/mtd/mtdcore.c
@@ -577,7 +577,15 @@ int mtd_device_parse_register(struct mtd_info *mtd, const char * const *types,
                        err = -ENODEV;
        }
 
-       if (mtd->_reboot) {
+       /*
+        * FIXME: some drivers unfortunately call this function more than once.
+        * So we have to check if we've already assigned the reboot notifier.
+        *
+        * Generally, we can make multiple calls work for most cases, but it
+        * does cause problems with parse_mtd_partitions() above (e.g.,
+        * cmdlineparts will register partitions more than once).
+        */
+       if (mtd->_reboot && !mtd->reboot_notifier.notifier_call) {
                mtd->reboot_notifier.notifier_call = mtd_reboot_notifier;
                register_reboot_notifier(&mtd->reboot_notifier);
        }