Re: [PATCH 5/8] rcu: eliminate deadlock for rcu read site

From: Peter Zijlstra
Date: Mon Aug 12 2013 - 10:15:06 EST


On Mon, Aug 12, 2013 at 10:10:08AM -0400, Steven Rostedt wrote:
> On Mon, 12 Aug 2013 15:53:10 +0200
> Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
>
> > On Sat, Aug 10, 2013 at 11:43:59AM +0800, Lai Jiangshan wrote:
> > > Hi, Steven
> > >
> > > I was considering rtmutex's lock->wait_lock is a scheduler lock,
> > > But it is not, and it is just a spinlock of process context.
> > > I hope you change it to a spinlock of irq context.
> >
> > rwmutex::wait_lock is irq-safe; it had better be because its taken under
> > task_struct::pi_lock.
>
> It is? I thought it was the other way around. That is, pi_lock is taken
> under wait_lock.

Urgh, right you are.
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