Benjamin Herrenschmidt wrote:
On Thu, 2009-10-29 at 00:28 +0300, Valentine wrote:
Benjamin Herrenschmidt wrote:
On Wed, 2009-10-28 at 22:19 +0300, Valentine wrote:
I'm just not sure that we need to clear HARDIRQEN here, since we don't
really hard-disable the the interrupts.
We do, or rather, we come in with the interrupts hard disabled, no ?
Yes, looks like the interrupts are disabled at this point (before
preempt_schedule_irq) most of the times, but we don't hard-disable them
here. We just soft-disable them to make preempt_schedule_irq happy. Even
if an interrupt fires, it will be hard-disabled and the hardirq flag
will be cleared by the exception handler right away. I just think that
there's no need to clear hardirq flag if we don't clear MSR_EE.
My point is that MSR_EE _is_ already clear... isn't it ?
Yes, the MSR_EE is cleared before we jump to do_work. I'm OK with
clearing the hardirqenable flag. I just assumed that the hardirq flag
was supposed to reflect the MSR_EE state, so it looked a bit odd
clearing the MSR_EE at one place and then reflecting the change at another.
Anyway, the patch works fine.
Thanks,
Val.
So either we
set it back, or we clear HARDIRQEN to reflect it. It will be re-enable
as soon as preempt_schedule_irq() calls local_irq_enable() which is soon
enough anyways.
Also that avoids perf interrupt sneaking in since those act as NMIs in
that regard and -will- get in even when soft disabled.
Cheers,
Ben.
Thanks,
Val.
Ben.
Thanks,
Val.
+ TRACE_DISABLE_INTS
+
+ /* Call the scheduler with soft IRQs off */
+1: bl .preempt_schedule_irq
+
+ /* Hard-disable interrupts again (and update PACA) */
#ifdef CONFIG_PPC_BOOK3E
- wrteei 1
- bl .preempt_schedule
wrteei 0
#else
- ori r10,r10,MSR_EE
- mtmsrd r10,1 /* reenable interrupts */
- bl .preempt_schedule
mfmsr r10
- clrrdi r9,r1,THREAD_SHIFT
- rldicl r10,r10,48,1 /* disable interrupts again */
+ rldicl r10,r10,48,1
rotldi r10,r10,16
mtmsrd r10,1
#endif /* CONFIG_PPC_BOOK3E */
+ li r0,0
+ stb r0,PACAHARDIRQEN(r13)
+
+ /* Re-test flags and eventually loop */
+ clrrdi r9,r1,THREAD_SHIFT
ld r4,TI_FLAGS(r9)
andi. r0,r4,_TIF_NEED_RESCHED
bne 1b
b restore
user_work:
-#endif
+#endif /* CONFIG_PREEMPT */
+
/* Enable interrupts */
#ifdef CONFIG_PPC_BOOK3E
wrteei 1
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