linux-kernel - Re: [PATCH v2 08/15] platform/chrome: cros_ec_proto: handle empty payload in getting proto info

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Date:   Wed, 8 Jun 2022 02:16:58 +0000
From:   Tzung-Bi Shih <tzungbi@...nel.org>
To:     Guenter Roeck <groeck@...gle.com>
Cc:     bleung@...omium.org, groeck@...omium.org,
        chrome-platform@...ts.linux.dev, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v2 08/15] platform/chrome: cros_ec_proto: handle empty
 payload in getting proto info

On Tue, Jun 07, 2022 at 11:47:56AM -0700, Guenter Roeck wrote:
> On Tue, Jun 7, 2022 at 7:57 AM Tzung-Bi Shih <tzungbi@...nel.org> wrote:
> >
> > cros_ec_get_proto_info() expects to receive
> > sizeof(struct ec_response_get_protocol_info) from send_command().  The
> > payload is valid only if the return value is positive.
> >
> > Add Kunit tests for returning 0 in send_command() and handle the case in
> > cros_ec_get_proto_info().
> >
> That should be two separate patches.

Ack, will separate them in next version.  I put them together because I wrote
Kunit test first to make sure the second half takes effect (somehow TDD).

Could I still put the Kunit patch first (even if it introduces Kunit test
failure)?

> 
> > Signed-off-by: Tzung-Bi Shih <tzungbi@...nel.org>
> > ---
> > No v1.  New in the series.
> >
> >  drivers/platform/chrome/cros_ec_proto.c      |   5 +
> >  drivers/platform/chrome/cros_ec_proto_test.c | 132 +++++++++++++++++++
> >  2 files changed, 137 insertions(+)
> >
> > diff --git a/drivers/platform/chrome/cros_ec_proto.c b/drivers/platform/chrome/cros_ec_proto.c
> > index 893b76703da6..6f5be9e5ede4 100644
> > --- a/drivers/platform/chrome/cros_ec_proto.c
> > +++ b/drivers/platform/chrome/cros_ec_proto.c
> > @@ -314,6 +314,11 @@ static int cros_ec_get_proto_info(struct cros_ec_device *ec_dev, int devidx)
> >                 goto exit;
> >         }
> >
> > +       if (ret == 0) {
> > +               ret = -EPROTO;
> > +               goto exit;
> > +       }
> > +
> 
> I think you can move that into the if() statement above (which already
> checks for ret >=0),
> making it a special case of that situation.

Nope, there is no "ret >= 0" (you could be confusing with
cros_ec_get_host_event_wake_mask()).

The result flow roughly like:

ret = send_command(...);
if (ret < 0)
  goto exit;

mapped = cros_ec_map_error(...);
if (mapped) {
  ...
  goto exit;
}

if (ret == 0) {
  ...
  goto exit;
}