i8259.c spinlocks unnecessary

Benjamin Herrenschmidt benh at kernel.crashing.org
Sat Jun 29 23:55:42 EST 2002

>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.


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