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

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

[Rafael J. Wysocki]

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;
 }
 
 static inline void mtd_resume(struct mtd_info *mtd)

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

[Artem Bityutskiy]

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

[Rafael J. Wysocki]

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;
>  }
> 
> 

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

[Artem Bityutskiy]

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Thanks Rafael!

I've pushed this patch to l2-mtd-2.6.git (David, would you please merge
it upstream?).

Rafael, should I add some tags with your name like Tested-by or
Acked-by?


From d0eb0d769923d562781fcf43fdc6fa28e3823756 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>.

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)
-- 
1.7.8.3


-- 
Best Regards,
Artem Bityutskiy

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

[Oliver Neukum]

Am Montag, 16. Januar 2012, 10:17:21 schrieb Artem Bityutskiy:
> Thanks Rafael!
> 
> I've pushed this patch to l2-mtd-2.6.git (David, would you please merge
> it upstream?).

Does this need to go into stable?

	Regards
		Oliver

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

[Artem Bityutskiy]

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On Mon, 2012-01-16 at 10:23 +0100, Oliver Neukum wrote:
> Am Montag, 16. Januar 2012, 10:17:21 schrieb Artem Bityutskiy:
> > Thanks Rafael!
> > 
> > I've pushed this patch to l2-mtd-2.6.git (David, would you please merge
> > it upstream?).
> 
> Does this need to go into stable?

No, this is a regression introduced during this merge window. I'll amend
the commit message to make it clear, thanks.

-- 
Best Regards,
Artem Bityutskiy

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

[Rafael J. Wysocki]

On Monday, January 16, 2012, Artem Bityutskiy wrote:
> Thanks Rafael!
> 
> I've pushed this patch to l2-mtd-2.6.git (David, would you please merge
> it upstream?).
> 
> Rafael, should I add some tags with your name like Tested-by or
> Acked-by?

Traditionally, the "Reported-and-tested-by" tag is used for such things,
so you can do that too ...

Thanks,
Rafael


> From d0eb0d769923d562781fcf43fdc6fa28e3823756 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>.
> 
> 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)
> 

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

[Rafael J. Wysocki]

On Monday, January 16, 2012, Artem Bityutskiy wrote:
> Thanks Rafael!
> 
> I've pushed this patch to l2-mtd-2.6.git (David, would you please merge
> it upstream?).
> 
> Rafael, should I add some tags with your name like Tested-by or
> Acked-by?
> 
> 
> From d0eb0d769923d562781fcf43fdc6fa28e3823756 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>.

Reported-and-tested-by: Rafael J. Wysocki <rjw@sisk.pl>

Is there any plan to push this patch to Linus for 3.3?  It fixes a rather
nasty suspend regression.

Thanks,
Rafael


> 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)
>