Re: [PATCH] rtmutex: multiple candidate owners without unrelatedboosting

From: Thomas Gleixner
Date: Wed Dec 15 2010 - 03:03:06 EST


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
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