[PATCH] drivers: pnp: proc.c: Handle errors while attaching devices

[PATCH] drivers: pnp: proc.c: Handle errors while attaching devices

[Anupama K Patil]

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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);
+	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;
 }
-- 
2.25.1


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Re: [PATCH] drivers: pnp: proc.c: Handle errors while attaching devices

[Valdis Klētnieks]

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On Sun, 25 Apr 2021 01:13:01 +0530, Anupama K Patil said:
> Changed sprintf() to the kernel-space function scnprintf() as it returns
> the actual number of bytes written.

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

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

Why do this when you don't *use* the number of bytes written, but instead ignore
the value returned?

For bonus points:  Given the %02x format, under what conditions can it
return a value other than 2?


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Re: [PATCH] drivers: pnp: proc.c: Handle errors while attaching devices

[Barnabás Pőcze]

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

Re: [PATCH] drivers: pnp: proc.c: Handle errors while attaching devices

[Leon Romanovsky]

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

Re: [PATCH] drivers: pnp: proc.c: Handle errors while attaching devices

[bkkarthik]

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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
> 

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Re: [PATCH] drivers: pnp: proc.c: Handle errors while attaching devices

[Leon Romanovsky]

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

Re: [PATCH] drivers: pnp: proc.c: Handle errors while attaching devices

[Valdis Klētnieks]

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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.

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Re: [PATCH] drivers: pnp: proc.c: Handle errors while attaching devices

[Leon Romanovsky]

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

Re: [PATCH] drivers: pnp: proc.c: Handle errors while attaching devices

[Jaroslav Kysela]

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.

Re: [PATCH] drivers: pnp: proc.c: Handle errors while attaching devices

[Leon Romanovsky]

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.

Re: [PATCH] drivers: pnp: proc.c: Handle errors while attaching devices

[bkkarthik]

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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.

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Re: [PATCH] drivers: pnp: proc.c: Handle errors while attaching devices

[Jaroslav Kysela]

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.

Re: [PATCH] drivers: pnp: proc.c: Handle errors while attaching devices

[bkkarthik]

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.