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Commit a84195f3 authored by Arnd Bergmann's avatar Arnd Bergmann Committed by Paul Mackerras
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[PATCH] ppc64: fix IPI on bpa_iic 



This fixes a severe bug in the bpa_iic driver that caused
all sorts of problems.

We had been using incorrect priority values for inter processor
interrupts, which resulted in always doing CALL_FUNCTION
instead of RESCHEDULE or DEBUGGER_BREAK.

The symptoms cured by this patch include bad performance on
SMP systems spurious kernel panics in the IPI code.

Signed-off-by: default avatarArnd Bergmann <arndb@de.ibm.com>
Signed-off-by: default avatarPaul Mackerras <paulus@samba.org>
parent 5f502413

arch/ppc64/kernel/bpa_iic.c

+21 −7
Original line number Diff line number Diff line
@@ -205,6 +205,18 @@ static struct iic_regs __iomem *find_iic(int cpu) 
}



#ifdef CONFIG_SMP



/* Use the highest interrupt priorities for IPI */

static inline int iic_ipi_to_irq(int ipi)

{

	return IIC_IPI_OFFSET + IIC_NUM_IPIS - 1 - ipi;

}



static inline int iic_irq_to_ipi(int irq)

{

	return IIC_NUM_IPIS - 1 - (irq - IIC_IPI_OFFSET);

}



void iic_setup_cpu(void)

{

	out_be64(&__get_cpu_var(iic).regs->prio, 0xff);
@@ -212,18 +224,20 @@ void iic_setup_cpu(void) 


void iic_cause_IPI(int cpu, int mesg)

{

	out_be64(&per_cpu(iic, cpu).regs->generate, mesg);

	out_be64(&per_cpu(iic, cpu).regs->generate, (IIC_NUM_IPIS - 1 - mesg) << 4);

}



static irqreturn_t iic_ipi_action(int irq, void *dev_id, struct pt_regs *regs)

{



	smp_message_recv(irq - IIC_IPI_OFFSET, regs);

	smp_message_recv(iic_irq_to_ipi(irq), regs);

	return IRQ_HANDLED;

}



static void iic_request_ipi(int irq, const char *name)

static void iic_request_ipi(int ipi, const char *name)

{

	int irq;



	irq = iic_ipi_to_irq(ipi);

	/* IPIs are marked SA_INTERRUPT as they must run with irqs

	 * disabled */

	get_irq_desc(irq)->handler = &iic_pic;
@@ -233,10 +247,10 @@ static void iic_request_ipi(int irq, const char *name) 


void iic_request_IPIs(void)

{

	iic_request_ipi(IIC_IPI_OFFSET + PPC_MSG_CALL_FUNCTION, "IPI-call");

	iic_request_ipi(IIC_IPI_OFFSET + PPC_MSG_RESCHEDULE, "IPI-resched");

	iic_request_ipi(PPC_MSG_CALL_FUNCTION, "IPI-call");

	iic_request_ipi(PPC_MSG_RESCHEDULE, "IPI-resched");

#ifdef CONFIG_DEBUGGER

	iic_request_ipi(IIC_IPI_OFFSET + PPC_MSG_DEBUGGER_BREAK, "IPI-debug");

	iic_request_ipi(PPC_MSG_DEBUGGER_BREAK, "IPI-debug");

#endif /* CONFIG_DEBUGGER */

}

#endif /* CONFIG_SMP */