mtd: don't WARN about overloaded users of mtd->reboot_notifier.notifier_call

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Gitweb:     http://git.infradead.org/?p=mtd-2.6.git;a=commit;h=f8479dd6a03cfdc3b14e742045bfd8748cd86bd7
Commit:     f8479dd6a03cfdc3b14e742045bfd8748cd86bd7
Parent:     28ec8a864f4b67bb801aede7919391531612c7dd
Author:     Brian Norris <computersforpeace at gmail.com>
AuthorDate: Tue Nov 3 17:01:53 2015 -0800
Committer:  Brian Norris <computersforpeace at gmail.com>
CommitDate: Fri Nov 6 09:33:15 2015 -0800

    mtd: don't WARN about overloaded users of mtd->reboot_notifier.notifier_call
    
    There are multiple types of users of mtd->reboot_notifier.notifier_call:
    
    (1) A while back, the cfi_cmdset_000{1,2} chip drivers implemented a
    reboot notifier to (on a best effort basis) attempt to reset their flash
    chips before rebooting.
    
    (2) More recently, we implemented a common _reboot() hook so that MTD
    drivers (particularly, NAND flash) could better halt I/O operations
    without having to reimplement the same notifier boilerplate.
    
    Currently, the WARN_ONCE() condition here was written to handle (2), but
    at the same time it mis-diagnosed case (1) as an already-registered MTD.
    Let's fix this by having the WARN_ONCE() condition better imitate the
    condition that immediately follows it. (Wow, I don't know how I missed
    that one.)
    
    (Side note: Unfortunately, we can't yet combine the reboot notifier code
    for (1) and (2) with a patch like [1], because some users of (1) also
    use mtdconcat, and so the mtd_info struct from cfi_cmdset_000{1,2} won't
    actually get registered with mtdcore, and therefore their reboot
    notifier won't get registered.)
    
    [1] http://patchwork.ozlabs.org/patch/417981/
    
    Suggested-by: Guenter Roeck <linux at roeck-us.net>
    Signed-off-by: Brian Norris <computersforpeace at gmail.com>
    Cc: Jesper Nilsson <jespern at axis.com>
    Cc: linux-cris-kernel at axis.com
    Tested-by: Ezequiel Garcia <ezequiel at vanguardiasur.com.ar>
    Tested-by: Guenter Roeck <linux at roeck-us.net>
    Signed-off-by: Brian Norris <computersforpeace at gmail.com>
---
 drivers/mtd/mtdcore.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c
index b1eea48..a91cee9 100644
--- a/drivers/mtd/mtdcore.c
+++ b/drivers/mtd/mtdcore.c
@@ -616,7 +616,8 @@ int mtd_device_parse_register(struct mtd_info *mtd, const char * const *types,
 	 * does cause problems with parse_mtd_partitions() above (e.g.,
 	 * cmdlineparts will register partitions more than once).
 	 */
-	WARN_ONCE(mtd->reboot_notifier.notifier_call, "MTD already registered\n");
+	WARN_ONCE(mtd->_reboot && mtd->reboot_notifier.notifier_call,
+		  "MTD already registered\n");
 	if (mtd->_reboot && !mtd->reboot_notifier.notifier_call) {
 		mtd->reboot_notifier.notifier_call = mtd_reboot_notifier;
 		register_reboot_notifier(&mtd->reboot_notifier);