Messages in this thread | | | From | Roland McGrath <> | Subject | Re: + do_wait-wakeup-optimization.patch added to -mm tree | Date | Wed, 3 Dec 2008 17:06:48 -0800 (PST) |
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> Let's suppose the ptracer finds the EXIT_ZOMBIE tracee and notifies its > ->real_parent which sleeps in do_wait(). In that case the usage of > eligible_child(task == ptracer) above is bogus, and checking for > group_leader is not rifgt too.
I had overlooked that do_notify_parent() call.
> > +static int do_wait_wake_function(wait_queue_t *curr, unsigned mode, int sync, > > + void *key) > > +{ > > + struct task_struct *task = current; > > I think we can fix (and simplify) this code if we change __wake_up_parent(), > it should call __wake_up(key => p), so we can do > > struct task_struct *task = key;
I had not looked into the bowels of various __wake_up variants, just assumed it would stay as it is and use wake_up_interruptible_sync.
That would certainly be cleaner. Then do_wait_wake_function would not need the second of its special cases, only the one double-check for the thread_group_leader && task_detached case.
I don't see an exposed __wake_up* variant that both passes a "key" pointer through and does "sync". For __wake_up_parent, "sync" is quite desireable.
> > + if (!needs_wakeup(task, w)) > > + return 0; > > + > > + return default_wake_function(curr, mode, sync, key); > > perhaps autoremove_wake_function() makes more sense.
Why? The do_wait loop will have to go through again and still might just sleep again. The explicit remove at the end of do_wait seems fine to me.
Thanks, Roland
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