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    SubjectRE: [PATCH v2 1/5] hwmon: introduce hwmon_sanitize_name()
    Date
    From: Guenter Roeck
    > Sent: 30 March 2022 15:23
    > On 3/29/22 09:07, Michael Walle wrote:
    > > More and more drivers will check for bad characters in the hwmon name
    > > and all are using the same code snippet. Consolidate that code by adding
    > > a new hwmon_sanitize_name() function.
    > >
    > > Signed-off-by: Michael Walle <michael@walle.cc>
    > > ---
    > > Documentation/hwmon/hwmon-kernel-api.rst | 9 ++++-
    > > drivers/hwmon/hwmon.c | 49 ++++++++++++++++++++++++
    > > include/linux/hwmon.h | 3 ++
    > > 3 files changed, 60 insertions(+), 1 deletion(-)
    > >
    > > diff --git a/Documentation/hwmon/hwmon-kernel-api.rst b/Documentation/hwmon/hwmon-kernel-api.rst
    > > index c41eb6108103..12f4a9bcef04 100644
    > > --- a/Documentation/hwmon/hwmon-kernel-api.rst
    > > +++ b/Documentation/hwmon/hwmon-kernel-api.rst
    > > @@ -50,6 +50,10 @@ register/unregister functions::
    > >
    > > void devm_hwmon_device_unregister(struct device *dev);
    > >
    > > + char *hwmon_sanitize_name(const char *name);
    > > +
    > > + char *devm_hwmon_sanitize_name(struct device *dev, const char *name);
    > > +
    > > hwmon_device_register_with_groups registers a hardware monitoring device.
    > > The first parameter of this function is a pointer to the parent device.
    > > The name parameter is a pointer to the hwmon device name. The registration
    > > @@ -93,7 +97,10 @@ removal would be too late.
    > >
    > > All supported hwmon device registration functions only accept valid device
    > > names. Device names including invalid characters (whitespace, '*', or '-')
    > > -will be rejected. The 'name' parameter is mandatory.
    > > +will be rejected. The 'name' parameter is mandatory. Before calling a
    > > +register function you should either use hwmon_sanitize_name or
    > > +devm_hwmon_sanitize_name to replace any invalid characters with an
    > > +underscore.
    >
    > That needs more details and deserves its own paragraph. Calling one of
    > the functions is only necessary if the original name does or can include
    > unsupported characters; an unconditional "should" is therefore a bit
    > strong. Also, it is important to mention that the function duplicates
    > the name, and that it is the responsibility of the caller to release
    > the name if hwmon_sanitize_name() was called and the device is removed.

    More worrying, and not documented, is that the buffer 'name' points
    to must persist.

    ISTM that the kmalloc() in __hwmon_device_register() should include
    space for a copy of the name.
    It can then do what it will with whatever is passed in.

    Oh yes, it has my 'favourite construct': if (!strlen(name)) ...
    (well str[strlen(str)] = 0 also happens!)

    David

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