* i8259.c spinlocks unnecessary
@ 2002-06-28 21:29 Cort Dougan
2002-06-29 13:55 ` Benjamin Herrenschmidt
0 siblings, 1 reply; 3+ messages in thread
From: Cort Dougan @ 2002-06-28 21:29 UTC (permalink / raw)
To: linuxppc-dev
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?
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^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: i8259.c spinlocks unnecessary
2002-06-28 21:29 i8259.c spinlocks unnecessary Cort Dougan
@ 2002-06-29 13:55 ` Benjamin Herrenschmidt
2002-06-29 14:28 ` Benjamin Herrenschmidt
0 siblings, 1 reply; 3+ messages in thread
From: Benjamin Herrenschmidt @ 2002-06-29 13:55 UTC (permalink / raw)
To: Cort Dougan, linuxppc-dev
>
>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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^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: i8259.c spinlocks unnecessary
2002-06-29 13:55 ` Benjamin Herrenschmidt
@ 2002-06-29 14:28 ` Benjamin Herrenschmidt
0 siblings, 0 replies; 3+ messages in thread
From: Benjamin Herrenschmidt @ 2002-06-29 14:28 UTC (permalink / raw)
To: Benjamin Herrenschmidt, Cort Dougan, linuxppc-dev
>irc.c don't have a global spinlock, only per-desc locks, so you can well
irq.c
I should sleep more ;)
Ben.
** Sent via the linuxppc-dev mail list. See http://lists.linuxppc.org/
^ permalink raw reply [flat|nested] 3+ messages in thread
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2002-06-28 21:29 i8259.c spinlocks unnecessary Cort Dougan
2002-06-29 13:55 ` Benjamin Herrenschmidt
2002-06-29 14:28 ` Benjamin Herrenschmidt
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