Re: [RFC PATCH 1/6] kernel: implement queue spinlock API

[Michel Lespinasse]

On Thu, Feb 7, 2013 at 9:03 PM, Paul E. McKenney
<paulmck@xxxxxxxxxxxxxxxxxx> wrote:
> Right...  For spinlocks that -don't- disable irqs, you need to deal with
> the possibility that a CPU gets interrupted while spinning, and the
> interrupt handler also tries to acquire a queued lock.  One way to deal
> with this is to have a node per CPUxirq.  Of course, if interrupts
> handlers always disable irqs when acquiring a spinlock, then you only
> need CPUx2.

The simple solution would be to do like I proposed in my faster queue
spinlock proposal, have one function for process context lock
acquisitions, another for bh-disabled acquisitions, and just say that
hardirqs can't use the queue spinlocks (I don't expect we have any
locks taken from hardirq context where contention might be an issue ?)

-- 
Michel "Walken" Lespinasse
A program is never fully debugged until the last user dies.
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