linux-kernel - Re: [PATCH] Input: iqs626a - Use common error handling code in iqs626_parse

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Message-ID: <ZeVOPSt0L1D4BxuZ@google.com>
Date: Sun, 3 Mar 2024 20:29:49 -0800
From: Dmitry Torokhov <dmitry.torokhov@...il.com>
To: Jeff LaBundy <jeff@...undy.com>
Cc: Markus Elfring <Markus.Elfring@....de>, linux-input@...r.kernel.org,
	kernel-janitors@...r.kernel.org, Rob Herring <robh@...nel.org>,
	Uwe Kleine-König <u.kleine-koenig@...gutronix.de>,
	LKML <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] Input: iqs626a - Use common error handling code in
 iqs626_parse_events()

On Sun, Mar 03, 2024 at 09:12:16PM -0600, Jeff LaBundy wrote:
> Hi Markus,
> 
> On Sat, Mar 02, 2024 at 12:42:08PM +0100, Markus Elfring wrote:
> > From: Markus Elfring <elfring@...rs.sourceforge.net>
> > Date: Sat, 2 Mar 2024 11:44:17 +0100
> > 
> > Add a jump target so that a bit of exception handling can be better reused
> > at the end of this function implementation.
> > 
> > This issue was transformed by using the Coccinelle software.
> > 
> > Signed-off-by: Markus Elfring <elfring@...rs.sourceforge.net>
> > ---
> >  drivers/input/misc/iqs626a.c | 13 +++++++------
> >  1 file changed, 7 insertions(+), 6 deletions(-)
> > 
> > diff --git a/drivers/input/misc/iqs626a.c b/drivers/input/misc/iqs626a.c
> > index 0dab54d3a060..fa9570755f7b 100644
> > --- a/drivers/input/misc/iqs626a.c
> > +++ b/drivers/input/misc/iqs626a.c
> > @@ -530,8 +530,7 @@ iqs626_parse_events(struct iqs626_private *iqs626,
> >  					dev_err(&client->dev,
> >  						"Invalid input type: %u\n",
> >  						val);
> > -					fwnode_handle_put(ev_node);
> > -					return -EINVAL;
> > +					goto put_fwnode;
> >  				}
> > 
> >  				iqs626->kp_type[ch_id][i] = val;
> > @@ -545,8 +544,7 @@ iqs626_parse_events(struct iqs626_private *iqs626,
> >  				dev_err(&client->dev,
> >  					"Invalid %s channel hysteresis: %u\n",
> >  					fwnode_get_name(ch_node), val);
> > -				fwnode_handle_put(ev_node);
> > -				return -EINVAL;
> > +				goto put_fwnode;
> >  			}
> > 
> >  			if (i == IQS626_EVENT_DEEP_DN ||
> > @@ -566,8 +564,7 @@ iqs626_parse_events(struct iqs626_private *iqs626,
> >  				dev_err(&client->dev,
> >  					"Invalid %s channel threshold: %u\n",
> >  					fwnode_get_name(ch_node), val);
> > -				fwnode_handle_put(ev_node);
> > -				return -EINVAL;
> > +				goto put_fwnode;
> >  			}
> > 
> >  			if (ch_id == IQS626_CH_HALL)
> > @@ -580,6 +577,10 @@ iqs626_parse_events(struct iqs626_private *iqs626,
> >  	}
> > 
> >  	return 0;
> > +
> > +put_fwnode:
> > +	fwnode_handle_put(ev_node);
> > +	return -EINVAL;
> >  }
> > 
> >  static noinline_for_stack int
> > --
> > 2.44.0
> > 
> 
> Thank you for this patch, but it seems like a NAK to me. I think this is
> a matter of personal preference, and according to mine, it is much more
> confusing to insert a goto label after a function's primary return path
> than to have 2-3 calls to fwnode_handle_put().
> 
> If you feel strongly otherwise, then I would suggest a helper function as
> recommended by Dmitry in another thread. However, maybe that helper should
> live in the driver core, as I suspect this driver is not the only place we
> can avoid calling fwnode_handle_put() in an error path that returns an int.

Yes, it should go into include/linux/fwnode.h, something like

DEFINE_FREE(fwnode, struct fwnode_handle *, if (_T) fwnode_hanlde_put(_T));

Then drivers can do:

	struct fwnode_handle *ev_node __free(fwnode) =
		fwnode_get_named_child_node(ch_node, ev_name);

and have it automatically be "put" once execution leaves the variable
scope.

Ah, we actually already have it defined in include/linux/property.h, all
the better.

Thanks.

-- 
Dmitry