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    SubjectRe: [PATCH 0 of 4] Generic AIO by scheduling stacks


    On Tue, 30 Jan 2007, Linus Torvalds wrote:
    >
    > Does that mean that we might not have some cases where we'd need to make
    > sure we do things differently? Of course not. Something migt show up. But
    > this actually makes it very clear what the difference between "struct
    > thread_struct" and "struct task_struct" are. One is shared between
    > fibrils, the other isn't.

    Btw, this is also something where we should just disallow certain system
    calls from being done through the asynchronous method.

    Notably, clone/fork(), execve() and exit() are all things that we probably
    simply shouldn't allow as "AIO" events.

    The process handling ones are obvious: they are very much about the shared
    "struct task_struct", so they rather clearly should only done "natively".

    More interesting is the question about "close()", though. Currently we
    have an optimization (fget/fput_light) that basically boils down to "we
    know we are the only owners". That optimization becomes more "interesting"
    with AIO - we need to disable it when fibrils are active (because other
    fibrils or the main thread can do it), but we can still keep it for the
    non-fibril case.

    So we can certainly allow close() to happen in a fibril, but at the same
    time, this is an area where just the *existence* of fibrils means that
    certain other decisions that were thread-related may be modified to be
    aware of the micro-threads too.

    I suspect there are rather few of those, though. The only one I can think
    of is literally the fget/fput_light() case, but there could be others.

    Linus
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