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    SubjectRe: Why /dev/sdc1 doesn't show up...
    > right).  Or you can run a notifier on "enlivening" a module: I'd hoped
    > to avoid that.

    Actually, after some thought, this seems to clearly be the Right
    Thing, because it solves another existing race. Consider a module
    which does:

    if (!register_foo(&my_foo))
    goto cleanup;
    if (!create_proc_entry(&my_entry))
    goto cleanup_foo;

    If register_foo() calls /sbin/hotplug, the module can still fail to
    load and /sbin/hotplug is called for something that doesn't exist.
    With the new module loader, you can also have /sbin/hotplug try to
    access the module before it's gone live, which will fail to prevent
    the "using before we know module won't fail init" race.

    Now, if you run /sbin/hotplug out of a notifier which is fired when
    the module actually goes live, this problem vanishes. It also means
    we can block module unload until /sbin/hotplug is run.

    The part that makes this feel like the Right Thing is that adding to

    /* THIS_MODULE == NULL */
    notifier_call_chain(&module_notifiers, MODULE_LIVE, NULL);

    means that /sbin/hotplug is called for everything which was registered
    at boot. (We may not want to do this, but in general the symmetry
    seems really nice).

    [ Note: the logic for /sbin/hotplug applies to any similar "publicity"
    function which promises that something now exists. ]

    Al, thoughts?
    Anyone who quotes me in their sig is an idiot. -- Rusty Russell.
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      Last update: 2005-03-22 13:31    [W:0.019 / U:18.572 seconds]
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