Messages in this thread | | | Date | Tue, 13 Feb 2007 23:10:52 +0100 | From | Ingo Molnar <> | Subject | Re: [patch 00/11] ANNOUNCE: "Syslets", generic asynchronous system call support |
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* Davide Libenzi <davidel@xmailserver.org> wrote:
> > If this is going to be a generic AIO subsystem: > > > > - Cancellation of peding request > > What about the busy_async_threads list becoming a hash/rb_tree indexed > by syslet_atom ptr. A cancel would lookup the thread and send a signal > (of course, signal handling of the async threads should be set > properly)?
well, each async syslet has a separate TID at the moment, so if we want a submitted syslet to be cancellable then we could return the TID of the syslet handler (instead of the NULL) in sys_async_exec(). Then user-space could send a signal the old-fashioned way, via sys_tkill(), if it so wishes.
the TID could also be used in a sys_async_wait_on() API. I.e. it would be a natural, readily accessible 'cookie' for the pending work. TIDs can be looked up lockless via RCU, so it's reasonably fast as well.
( Note that there's already a way to 'signal' pending syslets: do_exit() in the user context will signal all async contexts (which results in -EINTR of currently executing syscalls, wherever possible) and will tear them down. But that's too crude for aio_cancel() i guess. )
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