[PATCH RFC 2/2] mtd : Make the mtd_suspend return 0 if the suspend is not implemented

[dedekind1@gmail.com (Artem Bityutskiy)]

On Tue, 2012-01-24 at 09:06 +0000, Russell King - ARM Linux wrote:
> > However, the bug made it into the 3.3 merge window, so shouldn't this
> > bugfix be sent upstream immediately?
> 
> David is the MTD maintainer, and Artem just helps out.  I believe Artem
> is waiting for David to finish travelling before asking David (last seen
> at Hong Kong airport) to pull these fixes.  David in turn will pass them
> onto Linus.  Plus, Linus only started adding to -rc1 yesterday, so its a
> little early to expect this to be fixed.

Hi,

here is the latest version of the fix.

http://git.infradead.org/users/dedekind/l2-mtd-2.6.git/commit/283d43b9ce2952535aa89c0195085e2a1b7e5fce

Also attached.

>From 283d43b9ce2952535aa89c0195085e2a1b7e5fce Mon Sep 17 00:00:00 2001
From: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Date: Mon, 16 Jan 2012 11:07:16 +0200
Subject: [PATCH] mtd: fix MTD suspend

Commits 3fe4bae88460869a8e553397cd9057a4ee7ca341 and
079c985e7a6f4ce60f931cebfdd5ee3c3 broke MTD suspend in 2 ways:

1. When the '->suspend' method is not present, we return -EOPNOTSUPP,
but
   the callers of 'mtd_suspend()' expects 0 instead.
2. Checking of the 'mtd' parameter against NULL has been incorrectly
removed
   in 'mtd_cls_suspend()'.

This patch fixes the breakages. This has been found, analyzed, reported
and tested by Rafael J. Wysocki <rjw@sisk.pl>.

Note, this patch is not needed in the stable tree because it causes a
regression introduced during the v3.3 merge window.

Reported-by: Rafael J. Wysocki <rjw@sisk.pl>
Tested-by: Rafael J. Wysocki <rjw@sisk.pl>
Tested-by: Russell King <rmk+kernel@arm.linux.org.uk>
Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
---
 drivers/mtd/mtdcore.c   |    2 +-
 include/linux/mtd/mtd.h |    4 +---
 2 files changed, 2 insertions(+), 4 deletions(-)

diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c
index b265188..de96865 100644
--- a/drivers/mtd/mtdcore.c
+++ b/drivers/mtd/mtdcore.c
@@ -119,7 +119,7 @@ static int mtd_cls_suspend(struct device *dev,
pm_message_t state)
 {
 	struct mtd_info *mtd = dev_get_drvdata(dev);
 
-	return mtd_suspend(mtd);
+	return mtd ? mtd_suspend(mtd) : 0;
 }
 
 static int mtd_cls_resume(struct device *dev)
diff --git a/include/linux/mtd/mtd.h b/include/linux/mtd/mtd.h
index 1a81fde..d8c7aad 100644
--- a/include/linux/mtd/mtd.h
+++ b/include/linux/mtd/mtd.h
@@ -427,9 +427,7 @@ static inline int mtd_is_locked(struct mtd_info
*mtd, loff_t ofs, uint64_t len)
 
 static inline int mtd_suspend(struct mtd_info *mtd)
 {
-	if (!mtd->suspend)
-		return -EOPNOTSUPP;
-	return mtd->suspend(mtd);
+	return mtd->suspend ? mtd->suspend(mtd) : 0;
 }
 
 static inline void mtd_resume(struct mtd_info *mtd)
-- 
1.7.7.6

-- 
Best Regards,
Artem Bityutskiy
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