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>

1 files changed, 9 insertions, 1 deletions

diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c
index cbc0fc46d2d6..52eea932c312 100644
--- 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);
         }