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    SubjectRe: [PATCH 2/2] livepatch: Allow to unregister or free shadow data using a custom function
    On Tue, Mar 13, 2018 at 04:54:48PM +0100, Petr Mladek wrote:
    > We might need to do some actions before the shadow variable is freed.
    > For example, we might need to remove it from a list or free some data
    > that it points to.
    >
    > This is already possible now. The user can get the shadow variable
    > by klp_shadow_get(), do the necessary actions, and then call
    > klp_shadow_free().
    >
    > This patch allow to do this a more elegant way. The user could implement
    > the needed actions in a callback that is passed to klp_shadow_free()
    > as a parameter. The callback usually does reverse operations to
    > the init_func that can be called by klp_shadow_*alloc().
    >
    > It is especially useful for klp_shadow_free_all(). There we need to do
    > these extra actions for each found shadow variable with the given ID.
    >
    > Note that the memory used by the shadow variable itself is still released
    > later by rcu callback. It is needed to protect internal structures that
    > keep all shadow variables. But free_func is called immediately. The shadow
    > variable must not be access anyway after klp_shadow_free() is called.
    > The user is responsible to protect this any suitable way.
    >
    > Be aware that free_func callback is called under klp_shadow_lock. It is
    > the same as for init_func in klp_shadow_alloc().
    >
    > Signed-off-by: Petr Mladek <pmladek@suse.com>

    Makes sense, though I'm not sure "free" is the right name:

    a) "free" isn't the opposite of "init"; and

    b) it may be used for things other than freeing.

    Shall we call them constructor/destructor?

    --
    Josh

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