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Subject[PATCH v2 2/3] irqchip/sifive-plic: Setup cpuhp once after boot CPU handler is present
Date
For multiple PLIC instances, the plic_init() is called once for each
PLIC instance. Due to this we have two issues:
1. cpuhp_setup_state() is called multiple times
2. plic_starting_cpu() can crash for boot CPU if cpuhp_setup_state()
is called before boot CPU PLIC handler is available.

This patch fixes both above issues.

Fixes: f1ad1133b18f ("irqchip/sifive-plic: Add support for multiple PLICs")
Cc: stable@vger.kernel.org
Signed-off-by: Anup Patel <anup.patel@wdc.com>
---
drivers/irqchip/irq-sifive-plic.c | 14 ++++++++++++--
1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/drivers/irqchip/irq-sifive-plic.c b/drivers/irqchip/irq-sifive-plic.c
index 9f7f8ce88c00..6c54abf5cc5e 100644
--- a/drivers/irqchip/irq-sifive-plic.c
+++ b/drivers/irqchip/irq-sifive-plic.c
@@ -76,6 +76,7 @@ struct plic_handler {
void __iomem *enable_base;
struct plic_priv *priv;
};
+static bool plic_cpuhp_setup_done;
static DEFINE_PER_CPU(struct plic_handler, plic_handlers);

static inline void plic_toggle(struct plic_handler *handler,
@@ -285,6 +286,7 @@ static int __init plic_init(struct device_node *node,
int error = 0, nr_contexts, nr_handlers = 0, i;
u32 nr_irqs;
struct plic_priv *priv;
+ struct plic_handler *handler;

priv = kzalloc(sizeof(*priv), GFP_KERNEL);
if (!priv)
@@ -313,7 +315,6 @@ static int __init plic_init(struct device_node *node,

for (i = 0; i < nr_contexts; i++) {
struct of_phandle_args parent;
- struct plic_handler *handler;
irq_hw_number_t hwirq;
int cpu, hartid;

@@ -367,9 +368,18 @@ static int __init plic_init(struct device_node *node,
nr_handlers++;
}

- cpuhp_setup_state(CPUHP_AP_IRQ_SIFIVE_PLIC_STARTING,
+ /*
+ * We can have multiple PLIC instances so setup cpuhp state only
+ * when context handler for current/boot CPU is present.
+ */
+ handler = this_cpu_ptr(&plic_handlers);
+ if (handler->present && !plic_cpuhp_setup_done) {
+ cpuhp_setup_state(CPUHP_AP_IRQ_SIFIVE_PLIC_STARTING,
"irqchip/sifive/plic:starting",
plic_starting_cpu, plic_dying_cpu);
+ plic_cpuhp_setup_done = true;
+ }
+
pr_info("mapped %d interrupts with %d handlers for %d contexts.\n",
nr_irqs, nr_handlers, nr_contexts);
set_handle_irq(plic_handle_irq);
--
2.25.1
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