Re: [PATCH] Input: iqs626a - Use common error handling code in iqs626_parse_events()

Dmitry Torokhov
2024-03-04T04:29:52Z

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@users.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@users.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