drivers: pnp: proc.c: Handle errors while attaching devices

Message ID 20210424194301.jmsqpycvsm7izbk3@ubuntu
State New
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Series
  • drivers: pnp: proc.c: Handle errors while attaching devices
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Commit Message

Anupama K Patil April 24, 2021, 7:43 p.m.
isapnp_proc_init() does not look at the return value from
isapnp_proc_attach_device(). Check for this return value in
isapnp_proc_detach_device().

Cleanup in isapnp_proc_detach_device and
isapnp_proc_detach_bus() for cleanup.

Changed sprintf() to the kernel-space function scnprintf() as it returns
the actual number of bytes written.

Removed unnecessary variables de, e of type 'struct proc_dir_entry' to
save memory.

Suggested-by: Shuah Khan <skhan@linuxfoundation.org>
Co-developed-by: B K Karthik <bkkarthik@pesu.pes.edu>
Signed-off-by: B K Karthik <bkkarthik@pesu.pes.edu>
Signed-off-by: Anupama K Patil <anupamakpatil123@gmail.com>
---
 drivers/pnp/isapnp/proc.c | 40 +++++++++++++++++++++++++++++----------
 1 file changed, 30 insertions(+), 10 deletions(-)

Comments

Barnabás Pőcze April 25, 2021, 1:06 a.m. | #1
Hi


2021. április 24., szombat 21:43 keltezéssel, Anupama K Patil írta:

> isapnp_proc_init() does not look at the return value from
> isapnp_proc_attach_device(). Check for this return value in
> isapnp_proc_detach_device().
>
> Cleanup in isapnp_proc_detach_device and
> isapnp_proc_detach_bus() for cleanup.
>
> Changed sprintf() to the kernel-space function scnprintf() as it returns
> the actual number of bytes written.
>
> Removed unnecessary variables de, e of type 'struct proc_dir_entry' to
> save memory.
>
> Suggested-by: Shuah Khan <skhan@linuxfoundation.org>
> Co-developed-by: B K Karthik <bkkarthik@pesu.pes.edu>
> Signed-off-by: B K Karthik <bkkarthik@pesu.pes.edu>
> Signed-off-by: Anupama K Patil <anupamakpatil123@gmail.com>
> ---
>  drivers/pnp/isapnp/proc.c | 40 +++++++++++++++++++++++++++++----------
>  1 file changed, 30 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/pnp/isapnp/proc.c b/drivers/pnp/isapnp/proc.c
> index 785a796430fa..46ebc24175b7 100644
> --- a/drivers/pnp/isapnp/proc.c
> +++ b/drivers/pnp/isapnp/proc.c
> @@ -54,34 +54,54 @@ static const struct proc_ops isapnp_proc_bus_proc_ops = {
>  	.proc_read	= isapnp_proc_bus_read,
>  };
>
> +static int isapnp_proc_detach_device(struct pnp_dev *dev)
> +{
> +	proc_remove(dev->procent);
> +	dev->procent = NULL;
> +	return 0;
> +}
> +
> +static int isapnp_proc_detach_bus(struct pnp_card *bus)
> +{
> +	proc_remove(bus->procdir);

Is there any reason for not setting `bus->procdir` to `NULL`
similarly to the previous function?


> +	return 0;
> +}
> +

Is there any reason why the previous two functions return something? It doesn't
seem to be necessary.


>  static int isapnp_proc_attach_device(struct pnp_dev *dev)
>  {
>  	struct pnp_card *bus = dev->card;
> -	struct proc_dir_entry *de, *e;
>  	char name[16];
>
> -	if (!(de = bus->procdir)) {
> -		sprintf(name, "%02x", bus->number);
> -		de = bus->procdir = proc_mkdir(name, isapnp_proc_bus_dir);
> -		if (!de)
> +	if (!bus->procdir) {
> +		scnprintf(name, 16, "%02x", bus->number);

I think `sizeof(name)` would be preferable to hard-coding 16.


> +		bus->procdir = proc_mkdir(name, isapnp_proc_bus_dir);
> +		if (!bus->procdir)
>  			return -ENOMEM;
>  	}
> -	sprintf(name, "%02x", dev->number);
> -	e = dev->procent = proc_create_data(name, S_IFREG | S_IRUGO, de,
> +	scnprintf(name, 16, "%02x", dev->number);

Here as well.


> +	dev->procent = proc_create_data(name, S_IFREG | S_IRUGO, bus->procdir,
>  					    &isapnp_proc_bus_proc_ops, dev);

Please align the continuation properly.


> -	if (!e)
> +	if (!dev->procent) {
> +		isapnp_proc_detach_bus(bus);

I'm not sure if this should be here. If I'm not mistaken, the code
creates a procfs directory for a bus when it first sees a `pnp_dev` from that bus.
This call removes the whole directory for the bus, and with that, the files of
those `pnp_dev`s which were successfully created earlier.


>  		return -ENOMEM;
> -	proc_set_size(e, 256);
> +	}
> +	proc_set_size(dev->procent, 256);
>  	return 0;
>  }
>
>  int __init isapnp_proc_init(void)
>  {
>  	struct pnp_dev *dev;
> +	int dev_attach;
>
>  	isapnp_proc_bus_dir = proc_mkdir("bus/isapnp", NULL);

You could add a check to see if this `proc_mkdir()` call succeeds, and
possibly return early if it does not.


>  	protocol_for_each_dev(&isapnp_protocol, dev) {
> -		isapnp_proc_attach_device(dev);
> +		dev_attach = isapnp_proc_attach_device(dev);
> +		if (!dev_attach) {

`isapnp_proc_attach_device()` returns 0 on success, so the condition should be inverted.
And maybe `err` or something like that would be a better name than `dev_attach`.


> +			pr_info("procfs: pnp: Unable to attach the device, not enough memory");

If I'm not mistaken, allocation failures are logged, so this is probably not needed.


> +			isapnp_proc_detach_device(dev);

I'm also not sure if this is needed here. If `isapnp_proc_attach_device()` returns
an error, then `dev->procdir` could not have been "created". In other words,
if the execution reaches this point, `proc_create_data()` could not have succeeded
because either it had not yet been called or it had failed.


> +			return -ENOMEM;

It is usually preferable to return the error code you receive. E.g.:

  err = isapnp_proc_attach_device(...);
  if (err) {
    ...
    return err;
  }


> +		}
>  	}
>  	return 0;
>  }
> --
> 2.25.1
>


Regards,
Barnabás Pőcze
Leon Romanovsky April 26, 2021, 5:04 a.m. | #2
On Sun, Apr 25, 2021 at 01:13:01AM +0530, Anupama K Patil wrote:
> isapnp_proc_init() does not look at the return value from

> isapnp_proc_attach_device(). Check for this return value in

> isapnp_proc_detach_device().

> 

> Cleanup in isapnp_proc_detach_device and

> isapnp_proc_detach_bus() for cleanup.

> 

> Changed sprintf() to the kernel-space function scnprintf() as it returns

> the actual number of bytes written.

> 

> Removed unnecessary variables de, e of type 'struct proc_dir_entry' to

> save memory.


What exactly do you fix for such an old code?

> 

> Suggested-by: Shuah Khan <skhan@linuxfoundation.org>

> Co-developed-by: B K Karthik <bkkarthik@pesu.pes.edu>

> Signed-off-by: B K Karthik <bkkarthik@pesu.pes.edu>

> Signed-off-by: Anupama K Patil <anupamakpatil123@gmail.com>

> ---

>  drivers/pnp/isapnp/proc.c | 40 +++++++++++++++++++++++++++++----------

>  1 file changed, 30 insertions(+), 10 deletions(-)

> 

> diff --git a/drivers/pnp/isapnp/proc.c b/drivers/pnp/isapnp/proc.c

> index 785a796430fa..46ebc24175b7 100644

> --- a/drivers/pnp/isapnp/proc.c

> +++ b/drivers/pnp/isapnp/proc.c

> @@ -54,34 +54,54 @@ static const struct proc_ops isapnp_proc_bus_proc_ops = {

>  	.proc_read	= isapnp_proc_bus_read,

>  };

>  

> +static int isapnp_proc_detach_device(struct pnp_dev *dev)

> +{

> +	proc_remove(dev->procent);

> +	dev->procent = NULL;

> +	return 0;

> +}

> +

> +static int isapnp_proc_detach_bus(struct pnp_card *bus)

> +{

> +	proc_remove(bus->procdir);

> +	return 0;

> +}


Please don't add one line functions that are called only once and have
return value that no one care about it.

Thanks

> +

>  static int isapnp_proc_attach_device(struct pnp_dev *dev)

>  {

>  	struct pnp_card *bus = dev->card;

> -	struct proc_dir_entry *de, *e;

>  	char name[16];

>  

> -	if (!(de = bus->procdir)) {

> -		sprintf(name, "%02x", bus->number);

> -		de = bus->procdir = proc_mkdir(name, isapnp_proc_bus_dir);

> -		if (!de)

> +	if (!bus->procdir) {

> +		scnprintf(name, 16, "%02x", bus->number);

> +		bus->procdir = proc_mkdir(name, isapnp_proc_bus_dir);

> +		if (!bus->procdir)

>  			return -ENOMEM;

>  	}

> -	sprintf(name, "%02x", dev->number);

> -	e = dev->procent = proc_create_data(name, S_IFREG | S_IRUGO, de,

> +	scnprintf(name, 16, "%02x", dev->number);

> +	dev->procent = proc_create_data(name, S_IFREG | S_IRUGO, bus->procdir,

>  					    &isapnp_proc_bus_proc_ops, dev);

> -	if (!e)

> +	if (!dev->procent) {

> +		isapnp_proc_detach_bus(bus);

>  		return -ENOMEM;

> -	proc_set_size(e, 256);

> +	}

> +	proc_set_size(dev->procent, 256);

>  	return 0;

>  }

>  

>  int __init isapnp_proc_init(void)

>  {

>  	struct pnp_dev *dev;

> +	int dev_attach;

>  

>  	isapnp_proc_bus_dir = proc_mkdir("bus/isapnp", NULL);

>  	protocol_for_each_dev(&isapnp_protocol, dev) {

> -		isapnp_proc_attach_device(dev);

> +		dev_attach = isapnp_proc_attach_device(dev);

> +		if (!dev_attach) {

> +			pr_info("procfs: pnp: Unable to attach the device, not enough memory");

> +			isapnp_proc_detach_device(dev);

> +			return -ENOMEM;

> +		}

>  	}

>  	return 0;

>  }

> -- 

> 2.25.1

> 




> _______________________________________________

> Kernelnewbies mailing list

> Kernelnewbies@kernelnewbies.org

> https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
B K Karthik April 26, 2021, 5:50 p.m. | #3
On 21/04/26 08:04AM, Leon Romanovsky wrote:
> On Sun, Apr 25, 2021 at 01:13:01AM +0530, Anupama K Patil wrote:

> > isapnp_proc_init() does not look at the return value from

> > isapnp_proc_attach_device(). Check for this return value in

> > isapnp_proc_detach_device().

> > 

> > Cleanup in isapnp_proc_detach_device and

> > isapnp_proc_detach_bus() for cleanup.

> > 

> > Changed sprintf() to the kernel-space function scnprintf() as it returns

> > the actual number of bytes written.

> > 

> > Removed unnecessary variables de, e of type 'struct proc_dir_entry' to

> > save memory.

> 

> What exactly do you fix for such an old code?


I was not aware that this code is so old. This fix was made after checkpatch reported assignment inside an if-statement.
Please ignore this patch if th change is not necessary as the code is probably not being used anywhere :)

Maybe the code has to be marked as obsolete in the MAINTAINERS file to prevent patches being sent?

> 

> > 

> > Suggested-by: Shuah Khan <skhan@linuxfoundation.org>

> > Co-developed-by: B K Karthik <bkkarthik@pesu.pes.edu>

> > Signed-off-by: B K Karthik <bkkarthik@pesu.pes.edu>

> > Signed-off-by: Anupama K Patil <anupamakpatil123@gmail.com>

> > ---

> >  drivers/pnp/isapnp/proc.c | 40 +++++++++++++++++++++++++++++----------

> >  1 file changed, 30 insertions(+), 10 deletions(-)

> > 

> > diff --git a/drivers/pnp/isapnp/proc.c b/drivers/pnp/isapnp/proc.c

> > index 785a796430fa..46ebc24175b7 100644

> > --- a/drivers/pnp/isapnp/proc.c

> > +++ b/drivers/pnp/isapnp/proc.c

> > @@ -54,34 +54,54 @@ static const struct proc_ops isapnp_proc_bus_proc_ops = {

> >  	.proc_read	= isapnp_proc_bus_read,

> >  };

> >  

> > +static int isapnp_proc_detach_device(struct pnp_dev *dev)

> > +{

> > +	proc_remove(dev->procent);

> > +	dev->procent = NULL;

> > +	return 0;

> > +}

> > +

> > +static int isapnp_proc_detach_bus(struct pnp_card *bus)

> > +{

> > +	proc_remove(bus->procdir);

> > +	return 0;

> > +}

> 

> Please don't add one line functions that are called only once and have

> return value that no one care about it.


These were only intended for a clean-up job, the idea of this function came from how PCI handles procfs.
Maybe those should be changed?

thanks,

karthik

> 

> Thanks

> 

> > +

> >  static int isapnp_proc_attach_device(struct pnp_dev *dev)

> >  {

> >  	struct pnp_card *bus = dev->card;

> > -	struct proc_dir_entry *de, *e;

> >  	char name[16];

> >  

> > -	if (!(de = bus->procdir)) {

> > -		sprintf(name, "%02x", bus->number);

> > -		de = bus->procdir = proc_mkdir(name, isapnp_proc_bus_dir);

> > -		if (!de)

> > +	if (!bus->procdir) {

> > +		scnprintf(name, 16, "%02x", bus->number);

> > +		bus->procdir = proc_mkdir(name, isapnp_proc_bus_dir);

> > +		if (!bus->procdir)

> >  			return -ENOMEM;

> >  	}

> > -	sprintf(name, "%02x", dev->number);

> > -	e = dev->procent = proc_create_data(name, S_IFREG | S_IRUGO, de,

> > +	scnprintf(name, 16, "%02x", dev->number);

> > +	dev->procent = proc_create_data(name, S_IFREG | S_IRUGO, bus->procdir,

> >  					    &isapnp_proc_bus_proc_ops, dev);

> > -	if (!e)

> > +	if (!dev->procent) {

> > +		isapnp_proc_detach_bus(bus);

> >  		return -ENOMEM;

> > -	proc_set_size(e, 256);

> > +	}

> > +	proc_set_size(dev->procent, 256);

> >  	return 0;

> >  }

> >  

> >  int __init isapnp_proc_init(void)

> >  {

> >  	struct pnp_dev *dev;

> > +	int dev_attach;

> >  

> >  	isapnp_proc_bus_dir = proc_mkdir("bus/isapnp", NULL);

> >  	protocol_for_each_dev(&isapnp_protocol, dev) {

> > -		isapnp_proc_attach_device(dev);

> > +		dev_attach = isapnp_proc_attach_device(dev);

> > +		if (!dev_attach) {

> > +			pr_info("procfs: pnp: Unable to attach the device, not enough memory");

> > +			isapnp_proc_detach_device(dev);

> > +			return -ENOMEM;

> > +		}

> >  	}

> >  	return 0;

> >  }

> > -- 

> > 2.25.1

> > 

> 

> 

> 

> > _______________________________________________

> > Kernelnewbies mailing list

> > Kernelnewbies@kernelnewbies.org

> > https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies

>
Leon Romanovsky April 27, 2021, 4:26 a.m. | #4
On Mon, Apr 26, 2021 at 11:20:32PM +0530, bkkarthik wrote:
> On 21/04/26 08:04AM, Leon Romanovsky wrote:

> > On Sun, Apr 25, 2021 at 01:13:01AM +0530, Anupama K Patil wrote:

> > > isapnp_proc_init() does not look at the return value from

> > > isapnp_proc_attach_device(). Check for this return value in

> > > isapnp_proc_detach_device().

> > > 

> > > Cleanup in isapnp_proc_detach_device and

> > > isapnp_proc_detach_bus() for cleanup.

> > > 

> > > Changed sprintf() to the kernel-space function scnprintf() as it returns

> > > the actual number of bytes written.

> > > 

> > > Removed unnecessary variables de, e of type 'struct proc_dir_entry' to

> > > save memory.


<...>

> > > +static int isapnp_proc_detach_device(struct pnp_dev *dev)

> > > +{

> > > +	proc_remove(dev->procent);

> > > +	dev->procent = NULL;

> > > +	return 0;

> > > +}

> > > +

> > > +static int isapnp_proc_detach_bus(struct pnp_card *bus)

> > > +{

> > > +	proc_remove(bus->procdir);

> > > +	return 0;

> > > +}

> > 

> > Please don't add one line functions that are called only once and have

> > return value that no one care about it.

> 

> These were only intended for a clean-up job, the idea of this function came from how PCI handles procfs.

> Maybe those should be changed?


Probably, the CONFIG_PROC_FS around pci_proc_*() is not needed too.

Thanks
Jaroslav Kysela April 28, 2021, 12:04 p.m. | #5
Dne 26. 04. 21 v 19:50 bkkarthik napsal(a):
> On 21/04/26 08:04AM, Leon Romanovsky wrote:

>> On Sun, Apr 25, 2021 at 01:13:01AM +0530, Anupama K Patil wrote:

>>> isapnp_proc_init() does not look at the return value from

>>> isapnp_proc_attach_device(). Check for this return value in

>>> isapnp_proc_detach_device().

>>>

>>> Cleanup in isapnp_proc_detach_device and

>>> isapnp_proc_detach_bus() for cleanup.

>>>

>>> Changed sprintf() to the kernel-space function scnprintf() as it returns

>>> the actual number of bytes written.

>>>

>>> Removed unnecessary variables de, e of type 'struct proc_dir_entry' to

>>> save memory.

>>

>> What exactly do you fix for such an old code?

> 

> I was not aware that this code is so old. This fix was made after checkpatch reported assignment inside an if-statement.

> Please ignore this patch if th change is not necessary as the code is probably not being used anywhere :)

> 

> Maybe the code has to be marked as obsolete in the MAINTAINERS file to prevent patches being sent?

> 

>>

>>>

>>> Suggested-by: Shuah Khan <skhan@linuxfoundation.org>

>>> Co-developed-by: B K Karthik <bkkarthik@pesu.pes.edu>

>>> Signed-off-by: B K Karthik <bkkarthik@pesu.pes.edu>

>>> Signed-off-by: Anupama K Patil <anupamakpatil123@gmail.com>

>>> ---

>>>  drivers/pnp/isapnp/proc.c | 40 +++++++++++++++++++++++++++++----------

>>>  1 file changed, 30 insertions(+), 10 deletions(-)

>>>

>>> diff --git a/drivers/pnp/isapnp/proc.c b/drivers/pnp/isapnp/proc.c

>>> index 785a796430fa..46ebc24175b7 100644

>>> --- a/drivers/pnp/isapnp/proc.c

>>> +++ b/drivers/pnp/isapnp/proc.c

>>> @@ -54,34 +54,54 @@ static const struct proc_ops isapnp_proc_bus_proc_ops = {

>>>  	.proc_read	= isapnp_proc_bus_read,

>>>  };

>>>  

>>> +static int isapnp_proc_detach_device(struct pnp_dev *dev)

>>> +{

>>> +	proc_remove(dev->procent);

>>> +	dev->procent = NULL;

>>> +	return 0;

>>> +}

>>> +

>>> +static int isapnp_proc_detach_bus(struct pnp_card *bus)

>>> +{

>>> +	proc_remove(bus->procdir);

>>> +	return 0;

>>> +}

>>

>> Please don't add one line functions that are called only once and have

>> return value that no one care about it.

> 

> These were only intended for a clean-up job, the idea of this function came from how PCI handles procfs.

> Maybe those should be changed?


Which code you refer? I see:

       for_each_pci_dev(dev)
                pci_proc_attach_device(dev);


The error codes are ignored, too. It does not harm, if proc entries are not
created (in this case - the system is unstable anyway). We should concentrate
only to the wrong pointers usage.

						Jaroslav

-- 
Jaroslav Kysela <perex@perex.cz>
Linux Sound Maintainer; ALSA Project; Red Hat, Inc.
Leon Romanovsky April 28, 2021, 12:21 p.m. | #6
On Wed, Apr 28, 2021 at 02:04:49PM +0200, Jaroslav Kysela wrote:
> Dne 26. 04. 21 v 19:50 bkkarthik napsal(a):

> > On 21/04/26 08:04AM, Leon Romanovsky wrote:

> >> On Sun, Apr 25, 2021 at 01:13:01AM +0530, Anupama K Patil wrote:

> >>> isapnp_proc_init() does not look at the return value from

> >>> isapnp_proc_attach_device(). Check for this return value in

> >>> isapnp_proc_detach_device().

> >>>

> >>> Cleanup in isapnp_proc_detach_device and

> >>> isapnp_proc_detach_bus() for cleanup.

> >>>

> >>> Changed sprintf() to the kernel-space function scnprintf() as it returns

> >>> the actual number of bytes written.

> >>>

> >>> Removed unnecessary variables de, e of type 'struct proc_dir_entry' to

> >>> save memory.

> >>

> >> What exactly do you fix for such an old code?

> > 

> > I was not aware that this code is so old. This fix was made after checkpatch reported assignment inside an if-statement.

> > Please ignore this patch if th change is not necessary as the code is probably not being used anywhere :)

> > 

> > Maybe the code has to be marked as obsolete in the MAINTAINERS file to prevent patches being sent?

> > 

> >>

> >>>

> >>> Suggested-by: Shuah Khan <skhan@linuxfoundation.org>

> >>> Co-developed-by: B K Karthik <bkkarthik@pesu.pes.edu>

> >>> Signed-off-by: B K Karthik <bkkarthik@pesu.pes.edu>

> >>> Signed-off-by: Anupama K Patil <anupamakpatil123@gmail.com>

> >>> ---

> >>>  drivers/pnp/isapnp/proc.c | 40 +++++++++++++++++++++++++++++----------

> >>>  1 file changed, 30 insertions(+), 10 deletions(-)

> >>>

> >>> diff --git a/drivers/pnp/isapnp/proc.c b/drivers/pnp/isapnp/proc.c

> >>> index 785a796430fa..46ebc24175b7 100644

> >>> --- a/drivers/pnp/isapnp/proc.c

> >>> +++ b/drivers/pnp/isapnp/proc.c

> >>> @@ -54,34 +54,54 @@ static const struct proc_ops isapnp_proc_bus_proc_ops = {

> >>>  	.proc_read	= isapnp_proc_bus_read,

> >>>  };

> >>>  

> >>> +static int isapnp_proc_detach_device(struct pnp_dev *dev)

> >>> +{

> >>> +	proc_remove(dev->procent);

> >>> +	dev->procent = NULL;

> >>> +	return 0;

> >>> +}

> >>> +

> >>> +static int isapnp_proc_detach_bus(struct pnp_card *bus)

> >>> +{

> >>> +	proc_remove(bus->procdir);

> >>> +	return 0;

> >>> +}

> >>

> >> Please don't add one line functions that are called only once and have

> >> return value that no one care about it.

> > 

> > These were only intended for a clean-up job, the idea of this function came from how PCI handles procfs.

> > Maybe those should be changed?

> 

> Which code you refer? I see:

> 

>        for_each_pci_dev(dev)

>                 pci_proc_attach_device(dev);


He talks about isapnp_proc_detach_*() functions.

> 

> 

> The error codes are ignored, too. It does not harm, if proc entries are not

> created (in this case - the system is unstable anyway). We should concentrate

> only to the wrong pointers usage.

> 

> 						Jaroslav

> 

> -- 

> Jaroslav Kysela <perex@perex.cz>

> Linux Sound Maintainer; ALSA Project; Red Hat, Inc.
B K Karthik April 28, 2021, 12:26 p.m. | #7
On 21/04/28 03:21PM, Leon Romanovsky wrote:
> On Wed, Apr 28, 2021 at 02:04:49PM +0200, Jaroslav Kysela wrote:

> > Dne 26. 04. 21 v 19:50 bkkarthik napsal(a):

> > > On 21/04/26 08:04AM, Leon Romanovsky wrote:

> > >> On Sun, Apr 25, 2021 at 01:13:01AM +0530, Anupama K Patil wrote:

> > >>> isapnp_proc_init() does not look at the return value from

> > >>> isapnp_proc_attach_device(). Check for this return value in

> > >>> isapnp_proc_detach_device().

> > >>>

> > >>> Cleanup in isapnp_proc_detach_device and

> > >>> isapnp_proc_detach_bus() for cleanup.

> > >>>

> > >>> Changed sprintf() to the kernel-space function scnprintf() as it returns

> > >>> the actual number of bytes written.

> > >>>

> > >>> Removed unnecessary variables de, e of type 'struct proc_dir_entry' to

> > >>> save memory.

> > >>

> > >> What exactly do you fix for such an old code?

> > > 

> > > I was not aware that this code is so old. This fix was made after checkpatch reported assignment inside an if-statement.

> > > Please ignore this patch if th change is not necessary as the code is probably not being used anywhere :)

> > > 

> > > Maybe the code has to be marked as obsolete in the MAINTAINERS file to prevent patches being sent?

> > > 

> > >>

> > >>>

> > >>> Suggested-by: Shuah Khan <skhan@linuxfoundation.org>

> > >>> Co-developed-by: B K Karthik <bkkarthik@pesu.pes.edu>

> > >>> Signed-off-by: B K Karthik <bkkarthik@pesu.pes.edu>

> > >>> Signed-off-by: Anupama K Patil <anupamakpatil123@gmail.com>

> > >>> ---

> > >>>  drivers/pnp/isapnp/proc.c | 40 +++++++++++++++++++++++++++++----------

> > >>>  1 file changed, 30 insertions(+), 10 deletions(-)

> > >>>

> > >>> diff --git a/drivers/pnp/isapnp/proc.c b/drivers/pnp/isapnp/proc.c

> > >>> index 785a796430fa..46ebc24175b7 100644

> > >>> --- a/drivers/pnp/isapnp/proc.c

> > >>> +++ b/drivers/pnp/isapnp/proc.c

> > >>> @@ -54,34 +54,54 @@ static const struct proc_ops isapnp_proc_bus_proc_ops = {

> > >>>  	.proc_read	= isapnp_proc_bus_read,

> > >>>  };

> > >>>  

> > >>> +static int isapnp_proc_detach_device(struct pnp_dev *dev)

> > >>> +{

> > >>> +	proc_remove(dev->procent);

> > >>> +	dev->procent = NULL;

> > >>> +	return 0;

> > >>> +}

> > >>> +

> > >>> +static int isapnp_proc_detach_bus(struct pnp_card *bus)

> > >>> +{

> > >>> +	proc_remove(bus->procdir);

> > >>> +	return 0;

> > >>> +}

> > >>

> > >> Please don't add one line functions that are called only once and have

> > >> return value that no one care about it.

> > > 

> > > These were only intended for a clean-up job, the idea of this function came from how PCI handles procfs.

> > > Maybe those should be changed?

> > 

> > Which code you refer? I see:

> > 

> >        for_each_pci_dev(dev)

> >                 pci_proc_attach_device(dev);

> 

> He talks about isapnp_proc_detach_*() functions.


Yes, pci_proc_detach_device() and pci_proc_detach_bus() are both one-line functions as well.
I don't mean to question working code, we only tried to do something similar here for ISA.

thanks,

karthik

> 

> > 

> > 

> > The error codes are ignored, too. It does not harm, if proc entries are not

> > created (in this case - the system is unstable anyway). We should concentrate

> > only to the wrong pointers usage.

> > 

> > 						Jaroslav

> > 

> > -- 

> > Jaroslav Kysela <perex@perex.cz>

> > Linux Sound Maintainer; ALSA Project; Red Hat, Inc.
Jaroslav Kysela April 28, 2021, 12:30 p.m. | #8
Dne 28. 04. 21 v 14:21 Leon Romanovsky napsal(a):
> On Wed, Apr 28, 2021 at 02:04:49PM +0200, Jaroslav Kysela wrote:

>> Dne 26. 04. 21 v 19:50 bkkarthik napsal(a):

>>> On 21/04/26 08:04AM, Leon Romanovsky wrote:

>>>> On Sun, Apr 25, 2021 at 01:13:01AM +0530, Anupama K Patil wrote:

>>>>> isapnp_proc_init() does not look at the return value from

>>>>> isapnp_proc_attach_device(). Check for this return value in

>>>>> isapnp_proc_detach_device().

>>>>>

>>>>> Cleanup in isapnp_proc_detach_device and

>>>>> isapnp_proc_detach_bus() for cleanup.

>>>>>

>>>>> Changed sprintf() to the kernel-space function scnprintf() as it returns

>>>>> the actual number of bytes written.

>>>>>

>>>>> Removed unnecessary variables de, e of type 'struct proc_dir_entry' to

>>>>> save memory.

>>>>

>>>> What exactly do you fix for such an old code?

>>>

>>> I was not aware that this code is so old. This fix was made after checkpatch reported assignment inside an if-statement.

>>> Please ignore this patch if th change is not necessary as the code is probably not being used anywhere :)

>>>

>>> Maybe the code has to be marked as obsolete in the MAINTAINERS file to prevent patches being sent?

>>>

>>>>

>>>>>

>>>>> Suggested-by: Shuah Khan <skhan@linuxfoundation.org>

>>>>> Co-developed-by: B K Karthik <bkkarthik@pesu.pes.edu>

>>>>> Signed-off-by: B K Karthik <bkkarthik@pesu.pes.edu>

>>>>> Signed-off-by: Anupama K Patil <anupamakpatil123@gmail.com>

>>>>> ---

>>>>>  drivers/pnp/isapnp/proc.c | 40 +++++++++++++++++++++++++++++----------

>>>>>  1 file changed, 30 insertions(+), 10 deletions(-)

>>>>>

>>>>> diff --git a/drivers/pnp/isapnp/proc.c b/drivers/pnp/isapnp/proc.c

>>>>> index 785a796430fa..46ebc24175b7 100644

>>>>> --- a/drivers/pnp/isapnp/proc.c

>>>>> +++ b/drivers/pnp/isapnp/proc.c

>>>>> @@ -54,34 +54,54 @@ static const struct proc_ops isapnp_proc_bus_proc_ops = {

>>>>>  	.proc_read	= isapnp_proc_bus_read,

>>>>>  };

>>>>>  

>>>>> +static int isapnp_proc_detach_device(struct pnp_dev *dev)

>>>>> +{

>>>>> +	proc_remove(dev->procent);

>>>>> +	dev->procent = NULL;

>>>>> +	return 0;

>>>>> +}

>>>>> +

>>>>> +static int isapnp_proc_detach_bus(struct pnp_card *bus)

>>>>> +{

>>>>> +	proc_remove(bus->procdir);

>>>>> +	return 0;

>>>>> +}

>>>>

>>>> Please don't add one line functions that are called only once and have

>>>> return value that no one care about it.

>>>

>>> These were only intended for a clean-up job, the idea of this function came from how PCI handles procfs.

>>> Maybe those should be changed?

>>

>> Which code you refer? I see:

>>

>>        for_each_pci_dev(dev)

>>                 pci_proc_attach_device(dev);

> 

> He talks about isapnp_proc_detach_*() functions.


But only this patch introduced those functions. The pci_proc_init() code does
not call pci_proc_detach_*() functions and ignores the allocation errors, too.
I don't think that this cleanup code is required.

					Jaroslav

-- 
Jaroslav Kysela <perex@perex.cz>
Linux Sound Maintainer; ALSA Project; Red Hat, Inc.
B K Karthik April 28, 2021, 12:37 p.m. | #9
On 21/04/28 02:30PM, Jaroslav Kysela wrote:
> Dne 28. 04. 21 v 14:21 Leon Romanovsky napsal(a):

> > On Wed, Apr 28, 2021 at 02:04:49PM +0200, Jaroslav Kysela wrote:

> >> Dne 26. 04. 21 v 19:50 bkkarthik napsal(a):

> >>> On 21/04/26 08:04AM, Leon Romanovsky wrote:

> >>>> On Sun, Apr 25, 2021 at 01:13:01AM +0530, Anupama K Patil wrote:

> >>>>> isapnp_proc_init() does not look at the return value from

> >>>>> isapnp_proc_attach_device(). Check for this return value in

> >>>>> isapnp_proc_detach_device().

> >>>>>

> >>>>> Cleanup in isapnp_proc_detach_device and

> >>>>> isapnp_proc_detach_bus() for cleanup.

> >>>>>

> >>>>> Changed sprintf() to the kernel-space function scnprintf() as it returns

> >>>>> the actual number of bytes written.

> >>>>>

> >>>>> Removed unnecessary variables de, e of type 'struct proc_dir_entry' to

> >>>>> save memory.

> >>>>

> >>>> What exactly do you fix for such an old code?

> >>>

> >>> I was not aware that this code is so old. This fix was made after checkpatch reported assignment inside an if-statement.

> >>> Please ignore this patch if th change is not necessary as the code is probably not being used anywhere :)

> >>>

> >>> Maybe the code has to be marked as obsolete in the MAINTAINERS file to prevent patches being sent?

> >>>

> >>>>

> >>>>>

> >>>>> Suggested-by: Shuah Khan <skhan@linuxfoundation.org>

> >>>>> Co-developed-by: B K Karthik <bkkarthik@pesu.pes.edu>

> >>>>> Signed-off-by: B K Karthik <bkkarthik@pesu.pes.edu>

> >>>>> Signed-off-by: Anupama K Patil <anupamakpatil123@gmail.com>

> >>>>> ---

> >>>>>  drivers/pnp/isapnp/proc.c | 40 +++++++++++++++++++++++++++++----------

> >>>>>  1 file changed, 30 insertions(+), 10 deletions(-)

> >>>>>

> >>>>> diff --git a/drivers/pnp/isapnp/proc.c b/drivers/pnp/isapnp/proc.c

> >>>>> index 785a796430fa..46ebc24175b7 100644

> >>>>> --- a/drivers/pnp/isapnp/proc.c

> >>>>> +++ b/drivers/pnp/isapnp/proc.c

> >>>>> @@ -54,34 +54,54 @@ static const struct proc_ops isapnp_proc_bus_proc_ops = {

> >>>>>  	.proc_read	= isapnp_proc_bus_read,

> >>>>>  };

> >>>>>  

> >>>>> +static int isapnp_proc_detach_device(struct pnp_dev *dev)

> >>>>> +{

> >>>>> +	proc_remove(dev->procent);

> >>>>> +	dev->procent = NULL;

> >>>>> +	return 0;

> >>>>> +}

> >>>>> +

> >>>>> +static int isapnp_proc_detach_bus(struct pnp_card *bus)

> >>>>> +{

> >>>>> +	proc_remove(bus->procdir);

> >>>>> +	return 0;

> >>>>> +}

> >>>>

> >>>> Please don't add one line functions that are called only once and have

> >>>> return value that no one care about it.

> >>>

> >>> These were only intended for a clean-up job, the idea of this function came from how PCI handles procfs.

> >>> Maybe those should be changed?

> >>

> >> Which code you refer? I see:

> >>

> >>        for_each_pci_dev(dev)

> >>                 pci_proc_attach_device(dev);

> > 

> > He talks about isapnp_proc_detach_*() functions.

> 

> But only this patch introduced those functions. The pci_proc_init() code does

> not call pci_proc_detach_*() functions and ignores the allocation errors, too.


The changes in this patch make isapnp_proc_init() look at the return value of isapnp_proc_attach_device() and call isapnp_proc_detach_device() if that returns an error code.

> I don't think that this cleanup code is required.


Oh okay!

karthik

> 

> 					Jaroslav

> 

> -- 

> Jaroslav Kysela <perex@perex.cz>

> Linux Sound Maintainer; ALSA Project; Red Hat, Inc.
Valdis Kl=?utf-8?Q?=c4=93?=tnieks April 29, 2021, 4:31 a.m. | #10
On Tue, 27 Apr 2021 07:26:27 +0300, Leon Romanovsky said:
> On Mon, Apr 26, 2021 at 11:20:32PM +0530, bkkarthik wrote:

> > These were only intended for a clean-up job, the idea of this function came from how PCI handles procfs.

> > Maybe those should be changed?

>

> Probably, the CONFIG_PROC_FS around pci_proc_*() is not needed too.


Will that actually build correctly if it's an embedded system or something build with
CONFIG_PROC_FS=n?  I'd expect that to die a horrid death while linking vmlinx due
to stuff inside that #ifdef calling symbols only present with PROC_FS=m/y.

In general, inline ifdef's are frowned upon, so if you come across one in the kernel
source, that's probably a *big* hint that either (a) refactoring the code to eliminate
an inline ifdef was just too ugly to be allowed to live or (b) you *have* to put a guard
around it because you're guaranteed a build failure otherwise.
Leon Romanovsky April 29, 2021, 7:05 a.m. | #11
On Thu, Apr 29, 2021 at 12:31:13AM -0400, Valdis Klētnieks wrote:
> On Tue, 27 Apr 2021 07:26:27 +0300, Leon Romanovsky said:

> > On Mon, Apr 26, 2021 at 11:20:32PM +0530, bkkarthik wrote:

> > > These were only intended for a clean-up job, the idea of this function came from how PCI handles procfs.

> > > Maybe those should be changed?

> >

> > Probably, the CONFIG_PROC_FS around pci_proc_*() is not needed too.

> 

> Will that actually build correctly if it's an embedded system or something build with

> CONFIG_PROC_FS=n?  I'd expect that to die a horrid death while linking vmlinx due

> to stuff inside that #ifdef calling symbols only present with PROC_FS=m/y.


We are talking about pci_proc_detach_device() and pci_proc_detach_bus() here.
They will build perfectly without CONFIG_PROC_FS.

Thanks

Patch

diff --git a/drivers/pnp/isapnp/proc.c b/drivers/pnp/isapnp/proc.c
index 785a796430fa..46ebc24175b7 100644
--- a/drivers/pnp/isapnp/proc.c
+++ b/drivers/pnp/isapnp/proc.c
@@ -54,34 +54,54 @@  static const struct proc_ops isapnp_proc_bus_proc_ops = {
 	.proc_read	= isapnp_proc_bus_read,
 };
 
+static int isapnp_proc_detach_device(struct pnp_dev *dev)
+{
+	proc_remove(dev->procent);
+	dev->procent = NULL;
+	return 0;
+}
+
+static int isapnp_proc_detach_bus(struct pnp_card *bus)
+{
+	proc_remove(bus->procdir);
+	return 0;
+}
+
 static int isapnp_proc_attach_device(struct pnp_dev *dev)
 {
 	struct pnp_card *bus = dev->card;
-	struct proc_dir_entry *de, *e;
 	char name[16];
 
-	if (!(de = bus->procdir)) {
-		sprintf(name, "%02x", bus->number);
-		de = bus->procdir = proc_mkdir(name, isapnp_proc_bus_dir);
-		if (!de)
+	if (!bus->procdir) {
+		scnprintf(name, 16, "%02x", bus->number);
+		bus->procdir = proc_mkdir(name, isapnp_proc_bus_dir);
+		if (!bus->procdir)
 			return -ENOMEM;
 	}
-	sprintf(name, "%02x", dev->number);
-	e = dev->procent = proc_create_data(name, S_IFREG | S_IRUGO, de,
+	scnprintf(name, 16, "%02x", dev->number);
+	dev->procent = proc_create_data(name, S_IFREG | S_IRUGO, bus->procdir,
 					    &isapnp_proc_bus_proc_ops, dev);
-	if (!e)
+	if (!dev->procent) {
+		isapnp_proc_detach_bus(bus);
 		return -ENOMEM;
-	proc_set_size(e, 256);
+	}
+	proc_set_size(dev->procent, 256);
 	return 0;
 }
 
 int __init isapnp_proc_init(void)
 {
 	struct pnp_dev *dev;
+	int dev_attach;
 
 	isapnp_proc_bus_dir = proc_mkdir("bus/isapnp", NULL);
 	protocol_for_each_dev(&isapnp_protocol, dev) {
-		isapnp_proc_attach_device(dev);
+		dev_attach = isapnp_proc_attach_device(dev);
+		if (!dev_attach) {
+			pr_info("procfs: pnp: Unable to attach the device, not enough memory");
+			isapnp_proc_detach_device(dev);
+			return -ENOMEM;
+		}
 	}
 	return 0;
 }