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

Rafael J. Wysocki
2012-01-15T23:38:53Z

On Sunday, January 15, 2012, Artem Bityutskiy wrote:
> 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?

Yes, this works too.

Thanks,
Rafael

> 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;
> }
>
>