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

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Message-ID: <20210428123709.dbciscrm5qjr3bxa@burgerking>
Date:   Wed, 28 Apr 2021 18:07:09 +0530
From:   bkkarthik <bkkarthik@...u.pes.edu>
To:     Jaroslav Kysela <perex@...ex.cz>
Cc:     Leon Romanovsky <leon@...nel.org>,
        Anupama K Patil <anupamakpatil123@...il.com>,
        "Rafael J. Wysocki" <rafael.j.wysocki@...el.com>,
        linux-acpi@...r.kernel.org, linux-kernel@...r.kernel.org,
        skhan@...uxfoundation.org, gregkh@...uxfoundation.org,
        kernelnewbies@...nelnewbies.org
Subject: Re: [PATCH] drivers: pnp: proc.c: Handle errors while attaching
 devices

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@...uxfoundation.org>
> >>>>> Co-developed-by: B K Karthik <bkkarthik@...u.pes.edu>
> >>>>> Signed-off-by: B K Karthik <bkkarthik@...u.pes.edu>
> >>>>> Signed-off-by: Anupama K Patil <anupamakpatil123@...il.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@...ex.cz>
> Linux Sound Maintainer; ALSA Project; Red Hat, Inc.