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From:   Jorge Lopez <jorgealtxwork@gmail.com>
Date:   Fri, 28 Apr 2023 14:38:46 -0500
Message-ID: <CAOOmCE-6Mz5YoZs+Xac+p=+yFpL+EctVFsCsMum6SLzKYqTY5g@mail.gmail.com>
Subject: Re: [PATCH v11 08/14] HP BIOSCFG driver - bioscfg-h
To:     =?UTF-8?Q?Thomas_Wei=C3=9Fschuh?= <thomas@t-8ch.de>
Cc:     hdegoede@redhat.com, platform-driver-x86@vger.kernel.org,
        linux-kernel@vger.kernel.org
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On Fri, Apr 28, 2023 at 11:30=E2=80=AFAM Thomas Wei=C3=9Fschuh <thomas@t-8c=
h.de> wrote:
>
> On 2023-04-28 11:19:04-0500, Jorge Lopez wrote:
> > On Fri, Apr 28, 2023 at 11:09=E2=80=AFAM Thomas Wei=C3=9Fschuh <thomas@=
t-8ch.de> wrote:
> > >
> > > On 2023-04-28 11:03:56-0500, Jorge Lopez wrote:
> > > > On Fri, Apr 28, 2023 at 10:36=E2=80=AFAM Thomas Wei=C3=9Fschuh <tho=
mas@t-8ch.de> wrote:
> > > > >
> > > > > On 2023-04-28 10:24:40-0500, Jorge Lopez wrote:
> > > > > > On Sun, Apr 23, 2023 at 7:01=E2=80=AFAM Thomas Wei=C3=9Fschuh <=
thomas@t-8ch.de> wrote:
> > > > > > >
> > > > > > > On 2023-04-20 11:54:48-0500, Jorge Lopez wrote:
> > > > > > > > ---
> > > > > > > >  drivers/platform/x86/hp/hp-bioscfg/bioscfg.h | 613 +++++++=
++++++++++++
> > > > > > > >  1 file changed, 613 insertions(+)
> > > > > > > >  create mode 100644 drivers/platform/x86/hp/hp-bioscfg/bios=
cfg.h
> > >
> > > <snip>
> > >
> > > > > > > > +#define ATTRIBUTE_PROPERTY_STORE(curr_val, type)          =
           \
> > > > > > > > +     static ssize_t curr_val##_store(struct kobject *kobj,=
           \
> > > > > > > > +                                     struct kobj_attribute=
 *attr,    \
> > > > > > > > +                                     const char *buf, size=
_t count)  \
> > > > > > > > +     {                                                    =
           \
> > > > > > > > +             char *p =3D NULL;                            =
             \
> > > > > > > > +             char *attr_value =3D NULL;                   =
             \
> > > > > > > > +             int i;                                       =
           \
> > > > > > > > +             int ret =3D -EIO;                            =
             \
> > > > > > > > +                                                          =
           \
> > > > > > > > +             attr_value =3D kstrdup(buf, GFP_KERNEL);     =
             \
> > > > > > > > +             if (!attr_value)                             =
           \
> > > > > > > > +                     return -ENOMEM;                      =
           \
> > > > > > > > +                                                          =
           \
> > > > > > > > +             p =3D memchr(attr_value, '\n', count);       =
             \
> > > > > > > > +             if (p !=3D NULL)                             =
             \
> > > > > > > > +                     *p =3D '\0';                         =
             \
> > > > > > >
> > > > > > > This can also truncate the string if there is data after the =
newline.
> > > > > >
> > > > > > This is a expected behavior as described by Hans in a later ema=
il
> > > > >
> > > > > I'm fine with stripping a trailing newline.
> > > > >
> > > > > But this truncates the string at the first newline.
> > > > >
> > > > > "foo\nbar" -> "foo"
> > > > > "\nfoo" -> ""
> > > > >
> > > > All inputs expected by this driver and respectively by BIOS are a
> > > > single line.  For this reason, '\n' will cause the string to be
> > > > truncated.
> > > > I propose reporting a warning message indicating that the data ente=
red
> > > > has a '\n' character and will be truncated in addition to failing t=
he
> > > > operation with -EINVAL
> > >
> > > EINVAL sounds good, but a warning is overkill IMO.
> > >
> > > Whoever put in the garbage value will see the error.
> > >
> > > Stripping a trailing newline still seems fine though.
> >
> > So. should the driver return an -EINVAL error or truncate the line,
> > report a warning message, and allow it to proceed.?
> > Please advice
>
> p =3D memchr(attr_value, '\n', count)
> if (p =3D=3D attr_value + count - 1) {
>         *p =3D '\0'; /* strip trailing newline */
>         count--;
> } else if (p) {
>         return -EINVAL; /* enforce single line input */
> }
>
> (untested)
>
> When putting it into a helper you may need to adapt it a bit.
>
> > > This would be a very good candidate for a helper function.

Done!   Helper function created.