lkml.org 
[lkml]   [2002]   [Nov]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    From
    SubjectRe: Why /dev/sdc1 doesn't show up...
    Date
    > 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
    init/main.c:

    /* 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?
    Rusty.
    --
    Anyone who quotes me in their sig is an idiot. -- Rusty Russell.
    -
    To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
    the body of a message to majordomo@vger.kernel.org
    More majordomo info at http://vger.kernel.org/majordomo-info.html
    Please read the FAQ at http://www.tux.org/lkml/

    \
     
     \ /
      Last update: 2005-03-22 13:31    [W:0.022 / U:179.996 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site