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: Arnd Bergmann <[email protected]>
--- linux-2.6.13-rc6.orig/arch/ppc64/kernel/bpa_iic.c
+++ linux-2.6.13-rc6/arch/ppc64/kernel/bpa_iic.c
@@ -205,6 +205,18 @@ static struct iic_regs __iomem *find_iic
}
#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, con
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 */
-
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