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    SubjectRe: [PATCH v3 0/2] Fix ordering of ftrace/livepatch calls on module load and unload
    On Fri, Feb 05, 2016 at 10:08:15PM -0500, Jessica Yu wrote:
    > As explained here [1], livepatch modules are failing to initialize properly
    > because the ftrace coming module notifier (which calls
    > ftrace_module_enable()) runs *after* the livepatch module notifier (which
    > enables the patch(es)). Thus livepatch attempts to apply patches to
    > modules before ftrace_module_enable() is even called for the corresponding
    > module(s). As a result, patch modules break. Ftrace code must run before
    > livepatch on module load, and the reverse is true on module unload.
    >
    > For ftrace and livepatch, order of initialization (plus exit/cleanup code) is
    > important for loading and unloading modules, and using module notifiers to
    > perform this work is not ideal since it is not always clear what gets called
    > when. In this patchset, dependence on the module notifier call chain is removed
    > in favor of hard coding the corresponding function calls in the module loader.
    > This promotes better code visibility and ensures that ftrace and livepatch code
    > get called in the correct order on patch module load and unload.
    >
    > Tested the changes with a test livepatch module that patches 9p and nilfs2,
    > and verified that the issue described in [1] is fixed.

    Since Rusty agreed to your suggested changes for splitting up
    complete_formation() and for setting mod->state = MODULE_STATE_GOING
    before calling the going notifiers in the error path, can you do a v4
    with those changes? They should probably be split up like:

    1. split up complete_formation()
    2. set MODULE_STATE_GOING before calling going notifiers in error path
    3. remove ftrace module notifier
    4. remove livepatch module notifier

    --
    Josh

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