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

Dan Carpenter
2024-03-04T08:18:51Z

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@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.

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