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

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Date:   Wed, 28 Apr 2021 15:21:55 +0300
From:   Leon Romanovsky <leon@...nel.org>
To:     Jaroslav Kysela <perex@...ex.cz>
Cc:     bkkarthik <bkkarthik@...u.pes.edu>,
        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 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.

> 
> 
> 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@...ex.cz>
> Linux Sound Maintainer; ALSA Project; Red Hat, Inc.