Benjamin Herrenschmidt wrote:

On Thu, 2009-10-29 at 00:28 +0300, Valentine wrote:

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Benjamin Herrenschmidt wrote:

quoted

On Wed, 2009-10-28 at 22:19 +0300, Valentine wrote:

quoted

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.

quoted

Thanks,
Val.

quoted

Ben.

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Thanks,
Val.

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+	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