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

[bkkarthik]

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@xxxxxxxxxxxxxxxxxxx>
> > Co-developed-by: B K Karthik <bkkarthik@xxxxxxxxxxxx>
> > Signed-off-by: B K Karthik <bkkarthik@xxxxxxxxxxxx>
> > Signed-off-by: Anupama K Patil <anupamakpatil123@xxxxxxxxx>
> > ---
> >  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
> > 
> 
> 
> 
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