i8259.c spinlocks unnecessary

[Benjamin Herrenschmidt]

>
>I looked through the 8259 code and I believe the spinlocks there are
>unnecessary.  The code is covered by a spinlock when called from irq.c.
>
>I instrumented the code and after running quite some time my code review
>matches what I've seen.
>
>Anyone comment?  Does someone want to remove them?

irc.c don't have a global spinlock, only per-desc locks, so you can well
have one CPU dealing with an incoming interrupt and another CPU doing
a disable/enable_irq() on a different interrupt at the same time for
example. My understanding is that i8259 should be protected against
such races.

Ben.


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