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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