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authorRich Felker <dalias@libc.org>2016-10-08 21:11:27 -0400
committerRich Felker <dalias@libc.org>2016-10-18 18:56:11 -0400
commit0e42be2d5bb14f609856770d780468cfaa29c69a (patch)
treedfb06ccbdfd5a568ef8ebea12808d0264b193201
parent673f4a835d169f6cab75d8ac8e14ace8038f0c7d (diff)
downloadlinux-sh-0e42be2d5bb14f609856770d780468cfaa29c69a.tar.gz
irqchip/jcore: fix lost per-cpu interrupts
The J-Core AIC does not have separate interrupt numbers reserved for cpu-local vs global interrupts. Instead, the driver requesting the irq is expected to know whether its device uses per-cpu interrupts or not. Previously it was assumed that handle_simple_irq could work for both cases, but it intentionally drops interrupts for an irq number that already has a handler running. This resulted in the timer interrupt for one cpu being lost when multiple cpus' timers were set for approximately the same expiration time, leading to stalls. In theory the same could also happen with IPIs. To solve the problem, instead of registering handle_simple_irq as the handler, register a wrapper function which checks whether the irq to be handled was requested as per-cpu or not, and passes it to handle_simple_irq or handle_percpu_irq accordingly. Signed-off-by: Rich Felker <dalias@libc.org>
-rw-r--r--drivers/irqchip/irq-jcore-aic.c20
1 files changed, 19 insertions, 1 deletions
diff --git a/drivers/irqchip/irq-jcore-aic.c b/drivers/irqchip/irq-jcore-aic.c
index 5e5e3bb7d3c7..ed4d2339d0eb 100644
--- a/drivers/irqchip/irq-jcore-aic.c
+++ b/drivers/irqchip/irq-jcore-aic.c
@@ -25,12 +25,30 @@
static struct irq_chip jcore_aic;
+/*
+ * The J-Core AIC1 and AIC2 are cpu-local interrupt controllers and do
+ * not distinguish or use distinct irq number ranges for per-cpu event
+ * interrupts (timer, IPI). Since information to determine whether a
+ * particular irq number should be treated as per-cpu is not available
+ * at mapping time, we use a wrapper handler function which chooses
+ * the right handler at runtime based on whether IRQF_PERCPU was used
+ * when requesting the irq.
+ */
+
+static void handle_jcore_irq(struct irq_desc *desc)
+{
+ if (irqd_is_per_cpu(irq_desc_get_irq_data(desc)))
+ handle_percpu_irq(desc);
+ else
+ handle_simple_irq(desc);
+}
+
static int jcore_aic_irqdomain_map(struct irq_domain *d, unsigned int irq,
irq_hw_number_t hwirq)
{
struct irq_chip *aic = d->host_data;
- irq_set_chip_and_handler(irq, aic, handle_simple_irq);
+ irq_set_chip_and_handler(irq, aic, handle_jcore_irq);
return 0;
}