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    SubjectRe: [usb-storage] Re: [PATCH v4 12/12] RFC: watchdog: export core symbols in WATCHDOG_CORE namespace
    +++ Matthew Dharm [04/09/19 09:16 -0700]:
    >On Wed, Sep 4, 2019 at 5:12 AM Guenter Roeck <linux@roeck-us.net> wrote:
    >>
    >> Note that I don't object to the patch set in general. There may be symbols
    >> which only need be exported in the context of a single subsystem or even
    >> driver (if a driver consists of more than one module). For example, a mfd
    >> driver may export symbols which should only be called by its client drivers.
    >> In such a situation, it may well be beneficial to limit the use of exported
    >> symbols.
    >
    >I can appreciate this benefit.
    >
    >> I am not sure what good that does in practice (if I understand correctly,
    >> a driver only has to declare that it wants to use a restricted use symbol
    >> if it wants to use it), but that is a different question.
    >
    >I think this question implies that you are coming from the perspective
    >of "security" or wanting to restrict access to the underlying
    >functions, rather than wanting to clean-up the way symbols are handled
    >for manageability / maintainability purposes (which is the goal, as I
    >understand it).
    >
    >HOWEVER, I have one question: If these patches are included, and
    >someone wants to introduce a bit of code which needs to use two
    >symbols from different namespaces but with the same name, can that be
    >done? That is, if driver A has symbol 'foo' and driver B has symbol
    >'foo' (both in their respective namespaces), and driver C wants to use
    >A.foo and B.foo, can that be supported?

    As of now, we currently don't support this - modpost will warn if a
    symbol is exported more than once (across modules + vmlinux), and the
    module loader currently assumes exported symbol names are unique. Do
    you have a concrete use case? If there is a strong need for this, I
    don't think it'd be too hard to implement.

    Thanks,

    Jessica

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