Re: [patch] IA64: suppress return value of down_trylock() in salinfo_work_to_do()

[Matthew Wilcox <matthew@wil.cx>]

On Sat, Aug 02, 2008 at 07:32:00PM -0600, Matthew Wilcox wrote:
> I can't say that I think this is a good idea.  Has anyone looked at what
> it would take to actually track this?  For example, could we ever have
> the situation where:

Looking at this a bit more deeply, it seems to be a simple abuse of a
semaphore.

It's used both to exclude other tasks in salinfo_event_read() and as a
wake queue from interrupt context.  I think what we want is something
more like this:

	spin_lock(&data_saved_lock);
	if (!worktodo) {
		if (O_NONBLOCK)
			spin_unlock()
			return;
		else
			add to wait queue
			spin_unlock()
			schedule()
			spin_lock()
	}

Then we can just use wake_up() from interrupt context.

Thoughts?  I don't have any idea how to generate salinfo events, so I
wouldn't be able to test.

-- 
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