[PATCH] mtd: rawnand: mxc: remove __init qualifier from mxcnd_probe_dt

[PATCH] mtd: rawnand: mxc: remove __init qualifier from mxcnd_probe_dt

[Martin Kaiser]

mxcnd_probe_dt is called from mxcnd_probe, which is not marked as __init.

Using the sysfs unbind, bind nodes, mxcnd_probe and mxcnd_probe_dt can
potentially be called at any time. After the __init functions are cleaned,
mxcnd_probe_dt is no longer available. Calling it anyway causes a crash.

Signed-off-by: Martin Kaiser <martin@kaiser.cx>
---
I hope that my understanding is correct.

In practice, I could not get the kernel to crash, my compiler would
inline mxcnd_probe_dt into mxcnd_probe and ignore the __init.

If I marked mxcnd_probe_dt as noinline, I could trigger a crash as
follows

[root@host ]# echo bb000000.nand > /sys/bus/platform/drivers/mxc_nand/unbind
[root@host ]# echo bb000000.nand > /sys/bus/platform/drivers/mxc_nand/bind
Internal error: Oops - undefined instruction: 0 [#1] ARM
...

 drivers/mtd/nand/raw/mxc_nand.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/mtd/nand/raw/mxc_nand.c b/drivers/mtd/nand/raw/mxc_nand.c
index 26cef21..90cfb5e 100644
--- a/drivers/mtd/nand/raw/mxc_nand.c
+++ b/drivers/mtd/nand/raw/mxc_nand.c
@@ -1686,7 +1686,7 @@ static const struct of_device_id mxcnd_dt_ids[] = {
 };
 MODULE_DEVICE_TABLE(of, mxcnd_dt_ids);
 
-static int __init mxcnd_probe_dt(struct mxc_nand_host *host)
+static int mxcnd_probe_dt(struct mxc_nand_host *host)
 {
 	struct device_node *np = host->dev->of_node;
 	const struct of_device_id *of_id =
@@ -1700,7 +1700,7 @@ static int __init mxcnd_probe_dt(struct mxc_nand_host *host)
 	return 0;
 }
 #else
-static int __init mxcnd_probe_dt(struct mxc_nand_host *host)
+static int mxcnd_probe_dt(struct mxc_nand_host *host)
 {
 	return 1;
 }
-- 
2.1.4

Re: [PATCH] mtd: rawnand: mxc: remove __init qualifier from mxcnd_probe_dt

[Miquel Raynal]

Hi Martin, Boris,

On Fri, 22 Jun 2018 16:50:25 +0200, Martin Kaiser <martin@kaiser.cx>
wrote:

> mxcnd_probe_dt is called from mxcnd_probe, which is not marked as __init.
> 

I think this line is just a side note and should be at the end of the
commit log.

> Using the sysfs unbind, bind nodes, mxcnd_probe and mxcnd_probe_dt can
> potentially be called at any time. After the __init functions are cleaned,
> mxcnd_probe_dt is no longer available. Calling it anyway causes a crash.

The above paragraph explains the problem and the solution, you can just
add something like "mcvnd_probe is untouched because it is already not
marked as __init" instead of the first line.

> 
> Signed-off-by: Martin Kaiser <martin@kaiser.cx>

Boris, do you think this patch is a good candidate for stable?

If yes, Martin, could you please add a couple of stable/fixes tags above
your SoB?

Thanks,
Miquèl

> ---
> I hope that my understanding is correct.
> 
> In practice, I could not get the kernel to crash, my compiler would
> inline mxcnd_probe_dt into mxcnd_probe and ignore the __init.
> 
> If I marked mxcnd_probe_dt as noinline, I could trigger a crash as
> follows
> 
> [root@host ]# echo bb000000.nand > /sys/bus/platform/drivers/mxc_nand/unbind
> [root@host ]# echo bb000000.nand > /sys/bus/platform/drivers/mxc_nand/bind
> Internal error: Oops - undefined instruction: 0 [#1] ARM
> ...
> 
>  drivers/mtd/nand/raw/mxc_nand.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/mtd/nand/raw/mxc_nand.c b/drivers/mtd/nand/raw/mxc_nand.c
> index 26cef21..90cfb5e 100644
> --- a/drivers/mtd/nand/raw/mxc_nand.c
> +++ b/drivers/mtd/nand/raw/mxc_nand.c
> @@ -1686,7 +1686,7 @@ static const struct of_device_id mxcnd_dt_ids[] = {
>  };
>  MODULE_DEVICE_TABLE(of, mxcnd_dt_ids);
>  
> -static int __init mxcnd_probe_dt(struct mxc_nand_host *host)
> +static int mxcnd_probe_dt(struct mxc_nand_host *host)
>  {
>  	struct device_node *np = host->dev->of_node;
>  	const struct of_device_id *of_id =
> @@ -1700,7 +1700,7 @@ static int __init mxcnd_probe_dt(struct mxc_nand_host *host)
>  	return 0;
>  }
>  #else
> -static int __init mxcnd_probe_dt(struct mxc_nand_host *host)
> +static int mxcnd_probe_dt(struct mxc_nand_host *host)
>  {
>  	return 1;
>  }

Re: [PATCH] mtd: rawnand: mxc: remove __init qualifier from mxcnd_probe_dt

[Boris Brezillon]

On Tue, 26 Jun 2018 09:10:05 +0200
Miquel Raynal <miquel.raynal@bootlin.com> wrote:

> Hi Martin, Boris,
> 
> On Fri, 22 Jun 2018 16:50:25 +0200, Martin Kaiser <martin@kaiser.cx>
> wrote:
> 
> > mxcnd_probe_dt is called from mxcnd_probe, which is not marked as __init.
> >   
> 
> I think this line is just a side note and should be at the end of the
> commit log.
> 
> > Using the sysfs unbind, bind nodes, mxcnd_probe and mxcnd_probe_dt can
> > potentially be called at any time. After the __init functions are cleaned,
> > mxcnd_probe_dt is no longer available. Calling it anyway causes a crash.  
> 
> The above paragraph explains the problem and the solution, you can just
> add something like "mcvnd_probe is untouched because it is already not
> marked as __init" instead of the first line.
> 
> > 
> > Signed-off-by: Martin Kaiser <martin@kaiser.cx>  
> 
> Boris, do you think this patch is a good candidate for stable?
> 
> If yes, Martin, could you please add a couple of stable/fixes tags above
> your SoB?

We should at least have a Fixes tag. For the stable one, I'm not so
sure because the bug does not exist in practice (the compiler always
inline mxcnd_probe_dt()).

> 
> Thanks,
> Miquèl
> 
> > ---
> > I hope that my understanding is correct.
> > 
> > In practice, I could not get the kernel to crash, my compiler would
> > inline mxcnd_probe_dt into mxcnd_probe and ignore the __init.
> > 
> > If I marked mxcnd_probe_dt as noinline, I could trigger a crash as
> > follows
> > 
> > [root@host ]# echo bb000000.nand > /sys/bus/platform/drivers/mxc_nand/unbind
> > [root@host ]# echo bb000000.nand > /sys/bus/platform/drivers/mxc_nand/bind
> > Internal error: Oops - undefined instruction: 0 [#1] ARM
> > ...
> > 
> >  drivers/mtd/nand/raw/mxc_nand.c | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> > 
> > diff --git a/drivers/mtd/nand/raw/mxc_nand.c b/drivers/mtd/nand/raw/mxc_nand.c
> > index 26cef21..90cfb5e 100644
> > --- a/drivers/mtd/nand/raw/mxc_nand.c
> > +++ b/drivers/mtd/nand/raw/mxc_nand.c
> > @@ -1686,7 +1686,7 @@ static const struct of_device_id mxcnd_dt_ids[] = {
> >  };
> >  MODULE_DEVICE_TABLE(of, mxcnd_dt_ids);
> >  
> > -static int __init mxcnd_probe_dt(struct mxc_nand_host *host)
> > +static int mxcnd_probe_dt(struct mxc_nand_host *host)
> >  {
> >  	struct device_node *np = host->dev->of_node;
> >  	const struct of_device_id *of_id =
> > @@ -1700,7 +1700,7 @@ static int __init mxcnd_probe_dt(struct mxc_nand_host *host)
> >  	return 0;
> >  }
> >  #else
> > -static int __init mxcnd_probe_dt(struct mxc_nand_host *host)
> > +static int mxcnd_probe_dt(struct mxc_nand_host *host)
> >  {
> >  	return 1;
> >  }  

Re: [PATCH] mtd: rawnand: mxc: remove __init qualifier from mxcnd_probe_dt

[Miquel Raynal]

Hi Boris,

On Tue, 26 Jun 2018 09:24:13 +0200, Boris Brezillon
<boris.brezillon@bootlin.com> wrote:

> On Tue, 26 Jun 2018 09:10:05 +0200
> Miquel Raynal <miquel.raynal@bootlin.com> wrote:
> 
> > Hi Martin, Boris,
> > 
> > On Fri, 22 Jun 2018 16:50:25 +0200, Martin Kaiser <martin@kaiser.cx>
> > wrote:
> >   
> > > mxcnd_probe_dt is called from mxcnd_probe, which is not marked as __init.
> > >     
> > 
> > I think this line is just a side note and should be at the end of the
> > commit log.
> >   
> > > Using the sysfs unbind, bind nodes, mxcnd_probe and mxcnd_probe_dt can
> > > potentially be called at any time. After the __init functions are cleaned,
> > > mxcnd_probe_dt is no longer available. Calling it anyway causes a crash.    
> > 
> > The above paragraph explains the problem and the solution, you can just
> > add something like "mcvnd_probe is untouched because it is already not
> > marked as __init" instead of the first line.
> >   
> > > 
> > > Signed-off-by: Martin Kaiser <martin@kaiser.cx>    
> > 
> > Boris, do you think this patch is a good candidate for stable?
> > 
> > If yes, Martin, could you please add a couple of stable/fixes tags above
> > your SoB?  
> 
> We should at least have a Fixes tag. For the stable one, I'm not so
> sure because the bug does not exist in practice (the compiler always
> inline mxcnd_probe_dt()).

Fine, then a Fixes tag will be enough and I will take it into
nand/next as it is not urgent at all to have it in the main tree.


Miquèl

[PATCH v2] mtd: rawnand: mxc: remove __init qualifier from mxcnd_probe_dt

[Martin Kaiser]

Using the sysfs unbind, bind nodes, mxcnd_probe and mxcnd_probe_dt can
potentially be called at any time. After the __init functions are cleaned,
mxcnd_probe_dt is no longer available. Calling it anyway causes a crash.

mxcnd_probe used to be marked as __init, this was removed years ago.
Remove the __init qualifier from from mxcnd_probe_dt as well.

Fixes: 06f2551 ("mtd: remove use of __devinit")
Signed-off-by: Martin Kaiser <martin@kaiser.cx>
---
changes in v2
   - rephrased the commit message
   - added a Fixes: tag

 drivers/mtd/nand/raw/mxc_nand.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/mtd/nand/raw/mxc_nand.c b/drivers/mtd/nand/raw/mxc_nand.c
index 26cef21..90cfb5e 100644
--- a/drivers/mtd/nand/raw/mxc_nand.c
+++ b/drivers/mtd/nand/raw/mxc_nand.c
@@ -1686,7 +1686,7 @@ static const struct of_device_id mxcnd_dt_ids[] = {
 };
 MODULE_DEVICE_TABLE(of, mxcnd_dt_ids);
 
-static int __init mxcnd_probe_dt(struct mxc_nand_host *host)
+static int mxcnd_probe_dt(struct mxc_nand_host *host)
 {
 	struct device_node *np = host->dev->of_node;
 	const struct of_device_id *of_id =
@@ -1700,7 +1700,7 @@ static int __init mxcnd_probe_dt(struct mxc_nand_host *host)
 	return 0;
 }
 #else
-static int __init mxcnd_probe_dt(struct mxc_nand_host *host)
+static int mxcnd_probe_dt(struct mxc_nand_host *host)
 {
 	return 1;
 }
-- 
2.1.4

Re: [PATCH] mtd: rawnand: mxc: remove __init qualifier from mxcnd_probe_dt

[Martin Kaiser]

Hi Miquel & Boris,

thanks for your feedback.

Thus wrote Miquel Raynal (miquel.raynal@bootlin.com):

> Hi Boris,

> On Tue, 26 Jun 2018 09:24:13 +0200, Boris Brezillon
> <boris.brezillon@bootlin.com> wrote:

> > On Tue, 26 Jun 2018 09:10:05 +0200
> > Miquel Raynal <miquel.raynal@bootlin.com> wrote:

> > > Hi Martin, Boris,

> > > On Fri, 22 Jun 2018 16:50:25 +0200, Martin Kaiser <martin@kaiser.cx>
> > > wrote:

> > > > mxcnd_probe_dt is called from mxcnd_probe, which is not marked as __init.


> > > I think this line is just a side note and should be at the end of the
> > > commit log.

> > > > Using the sysfs unbind, bind nodes, mxcnd_probe and mxcnd_probe_dt can
> > > > potentially be called at any time. After the __init functions are cleaned,
> > > > mxcnd_probe_dt is no longer available. Calling it anyway causes a crash.    

> > > The above paragraph explains the problem and the solution, you can just
> > > add something like "mcvnd_probe is untouched because it is already not
> > > marked as __init" instead of the first line.


> > > > Signed-off-by: Martin Kaiser <martin@kaiser.cx>    

> > > Boris, do you think this patch is a good candidate for stable?

> > > If yes, Martin, could you please add a couple of stable/fixes tags above
> > > your SoB?  

> > We should at least have a Fixes tag. For the stable one, I'm not so
> > sure because the bug does not exist in practice (the compiler always
> > inline mxcnd_probe_dt()).

> Fine, then a Fixes tag will be enough and I will take it into
> nand/next as it is not urgent at all to have it in the main tree.

I agree that this is not a candidate for stable. I just sent an update
with a Fixes tag and rephrased commit message.

Best regards,
Martin

Re: [PATCH v2] mtd: rawnand: mxc: remove __init qualifier from mxcnd_probe_dt

[Miquel Raynal]

Hi Martin,

On Wed, 27 Jun 2018 10:52:37 +0200, Martin Kaiser <martin@kaiser.cx>
wrote:

> Using the sysfs unbind, bind nodes, mxcnd_probe and mxcnd_probe_dt can
> potentially be called at any time. After the __init functions are cleaned,
> mxcnd_probe_dt is no longer available. Calling it anyway causes a crash.
> 
> mxcnd_probe used to be marked as __init, this was removed years ago.
> Remove the __init qualifier from from mxcnd_probe_dt as well.
> 
> Fixes: 06f2551 ("mtd: remove use of __devinit")

Nitpick: the Fixes tag should use at least the 12 first characters of
the SHA-1 ID, see:

https://www.kernel.org/doc/html/v4.16/process/submitting-patches.html#describe-your-changes

Thanks,
Miquèl

[PATCH v3] mtd: rawnand: mxc: remove __init qualifier from mxcnd_probe_dt

[Martin Kaiser]

Using the sysfs unbind, bind nodes, mxcnd_probe and mxcnd_probe_dt can
potentially be called at any time. After the __init functions are cleaned,
mxcnd_probe_dt is no longer available. Calling it anyway causes a crash.

mxcnd_probe used to be marked as __init, this was removed years ago.
Remove the __init qualifier from from mxcnd_probe_dt as well.

Fixes: 06f255106923 ("mtd: remove use of __devinit")
Signed-off-by: Martin Kaiser <martin@kaiser.cx>
---
changes in v3
   - show the first 12 characters of the SHA-1 ID in the Fixes: tag

changes in v2
   - rephrased the commit message
   - added a Fixes: tag

 drivers/mtd/nand/raw/mxc_nand.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/mtd/nand/raw/mxc_nand.c b/drivers/mtd/nand/raw/mxc_nand.c
index 26cef218bb43..90cfb5e730aa 100644
--- a/drivers/mtd/nand/raw/mxc_nand.c
+++ b/drivers/mtd/nand/raw/mxc_nand.c
@@ -1686,7 +1686,7 @@ static const struct of_device_id mxcnd_dt_ids[] = {
 };
 MODULE_DEVICE_TABLE(of, mxcnd_dt_ids);
 
-static int __init mxcnd_probe_dt(struct mxc_nand_host *host)
+static int mxcnd_probe_dt(struct mxc_nand_host *host)
 {
 	struct device_node *np = host->dev->of_node;
 	const struct of_device_id *of_id =
@@ -1700,7 +1700,7 @@ static int __init mxcnd_probe_dt(struct mxc_nand_host *host)
 	return 0;
 }
 #else
-static int __init mxcnd_probe_dt(struct mxc_nand_host *host)
+static int mxcnd_probe_dt(struct mxc_nand_host *host)
 {
 	return 1;
 }
-- 
2.1.4

Re: [PATCH v3] mtd: rawnand: mxc: remove __init qualifier from mxcnd_probe_dt

[Boris Brezillon]

On Wed, 27 Jun 2018 22:47:44 +0200
Martin Kaiser <martin@kaiser.cx> wrote:

> Using the sysfs unbind, bind nodes, mxcnd_probe and mxcnd_probe_dt can
> potentially be called at any time. After the __init functions are cleaned,
> mxcnd_probe_dt is no longer available. Calling it anyway causes a crash.
> 
> mxcnd_probe used to be marked as __init, this was removed years ago.
> Remove the __init qualifier from from mxcnd_probe_dt as well.
> 
> Fixes: 06f255106923 ("mtd: remove use of __devinit")
> Signed-off-by: Martin Kaiser <martin@kaiser.cx>

Reviewed-by: Boris Brezillon <boris.brezillon@bootlin.com>

> ---
> changes in v3
>    - show the first 12 characters of the SHA-1 ID in the Fixes: tag
> 
> changes in v2
>    - rephrased the commit message
>    - added a Fixes: tag
> 
>  drivers/mtd/nand/raw/mxc_nand.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/mtd/nand/raw/mxc_nand.c b/drivers/mtd/nand/raw/mxc_nand.c
> index 26cef218bb43..90cfb5e730aa 100644
> --- a/drivers/mtd/nand/raw/mxc_nand.c
> +++ b/drivers/mtd/nand/raw/mxc_nand.c
> @@ -1686,7 +1686,7 @@ static const struct of_device_id mxcnd_dt_ids[] = {
>  };
>  MODULE_DEVICE_TABLE(of, mxcnd_dt_ids);
>  
> -static int __init mxcnd_probe_dt(struct mxc_nand_host *host)
> +static int mxcnd_probe_dt(struct mxc_nand_host *host)
>  {
>  	struct device_node *np = host->dev->of_node;
>  	const struct of_device_id *of_id =
> @@ -1700,7 +1700,7 @@ static int __init mxcnd_probe_dt(struct mxc_nand_host *host)
>  	return 0;
>  }
>  #else
> -static int __init mxcnd_probe_dt(struct mxc_nand_host *host)
> +static int mxcnd_probe_dt(struct mxc_nand_host *host)
>  {
>  	return 1;
>  }

Re: [PATCH v3] mtd: rawnand: mxc: remove __init qualifier from mxcnd_probe_dt

[Miquel Raynal]

Hi Martin,

Martin Kaiser <martin@kaiser.cx> wrote on Wed, 27 Jun 2018 22:47:44
+0200:

> Using the sysfs unbind, bind nodes, mxcnd_probe and mxcnd_probe_dt can
> potentially be called at any time. After the __init functions are cleaned,
> mxcnd_probe_dt is no longer available. Calling it anyway causes a crash.
> 
> mxcnd_probe used to be marked as __init, this was removed years ago.
> Remove the __init qualifier from from mxcnd_probe_dt as well.
> 
> Fixes: 06f255106923 ("mtd: remove use of __devinit")
> Signed-off-by: Martin Kaiser <martin@kaiser.cx>
> ---

Applied to nand/next, thanks!
Miquèl