Re: [PATCH] rtmutex: multiple candidate owners without unrelated boosting

Thomas Gleixner
2010-12-15T08:03:00Z

On Tue, 14 Dec 2010, Steven Rostedt wrote:

> On Tue, 2010-12-14 at 17:04 +0800, Lai Jiangshan wrote:
>
> OK, I was looking at this in a bit more detail (the coffee finally set
> in) and I was at first looking to nuke the cand_owner since it is
> redundant to cand_seq. But I think we can nuke the cand_seq instead and
> use the top_waiter as the decider.

So you just use cand_owner (the name sucks) to flag that the waiter
has been woken up either by the boost code or by an unlock. The waiter
clears that flag with waiter->lock->wait_lock held before calling
schedule().

Though I think we do need it at all. wakeup of an already running task
is almost a nop, so having one less state to worry about is good.

Thanks,

tglx