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

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Message-ID: <11e5db31-2a8f-458d-a249-7205e37aa20f@moroto.mountain>
Date: Mon, 4 Mar 2024 11:18:45 +0300
From: Dan Carpenter <dan.carpenter@...aro.org>
To: Dmitry Torokhov <dmitry.torokhov@...il.com>
Cc: Jeff LaBundy <jeff@...undy.com>, 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 08:29:49PM -0800, Dmitry Torokhov wrote:
> 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.

It's already there.

DEFINE_FREE(fwnode_handle, struct fwnode_handle *, fwnode_handle_put(_T))

I can send a patch for this.  You need to be a bit carefull to move
the declaration into the correct scope for this to work.  I should write
some Smatch rules for this...

regards,
dan carpenter