Re: [PATCH] PM / MTD: Fix regressions related to mtd_suspend()

Artem Bityutskiy
2012-01-15T14:21:50Z

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On Sun, 2012-01-15 at 14:43 +0100, Rafael J. Wysocki wrote:
> From: Rafael J. Wysocki <rjw@sisk.pl>
>
> Commit 3fe4bae88460869a8e553397cd9057a4ee7ca341 (mtd: introduce
> mtd_suspend interface) introduced the mtd_suspend() routine
> which didn't check whether or not mtd and mtd->suspend were
> both valid pointers. Later commit 079c985e7a6f4ce60f931cebfdd5ee3c3
> (mtd: do not use mtd->suspend and mtd->resume directly) added the
> check for mtd->suspend, but still it failed to check mtd. Moreover,
> it caused mtd_suspend() to return an error code for NULL
> mtd->suspend, which makes system suspend fail on one of my test
> systems on every attempt and which is a regression from v3.2.
>
> Fix mtd_suspend() by making it check if mtd is not NULL and
> return 0 if mtd or mtd->suspend is NULL, which shouldn't prevent
> the system from suspending.
>
> Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
> ---
> include/linux/mtd/mtd.h | 4 +---
> 1 file changed, 1 insertion(+), 3 deletions(-)
>
> Index: linux/include/linux/mtd/mtd.h
> ===================================================================
> --- linux.orig/include/linux/mtd/mtd.h
> +++ linux/include/linux/mtd/mtd.h
> @@ -427,9 +427,7 @@ static inline int mtd_is_locked(struct m
>
> static inline int mtd_suspend(struct mtd_info *mtd)
> {
> - if (!mtd->suspend)
> - return -EOPNOTSUPP;
> - return mtd->suspend(mtd);
> + return mtd && mtd->suspend ? mtd->suspend(mtd) : 0;
> }

Thanks! But All the MTD API functions assume that the "mtd" pointer is
non-NULL, and this function should to the same for consistency.

Would you please give this patch a test?

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;
}

--
Best Regards,
Artem Bityutskiy

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