linux-kernel - [PATCH 2/2] irqchip/sifive-plic: Fix the interrupt was enabled accidentally issue.

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Date:   Mon, 12 Oct 2020 21:57:24 +0800
From:   Greentime Hu <greentime.hu@...ive.com>
To:     greentime.hu@...ive.com, tglx@...utronix.de, jason@...edaemon.net,
        maz@...nel.org, palmer@...belt.com, paul.walmsley@...ive.com,
        linux-kernel@...r.kernel.org, linux-riscv@...ts.infradead.org
Subject: [PATCH 2/2] irqchip/sifive-plic: Fix the interrupt was enabled accidentally issue.

In commit 2ca0b460bbcb ("genirq/affinity: Make affinity setting if activated opt-in"),
it added irqd_affinity_on_activate() checking in the function
irq_set_affinity_deactivated() so it will return false here.
In that case, it will call irq_try_set_affinity() -> plic_irq_toggle()
which will enable the interrupt to cause the CPU hang.

	if (irq_set_affinity_deactivated())
		return 0;
	...
	irq_try_set_affinity(data, mask, force);

[  919.015783] rcu: INFO: rcu_sched detected stalls on CPUs/tasks:
[  919.020922] rcu:     0-...0: (0 ticks this GP)
idle=7d2/1/0x4000000000000002 softirq=1424/1424 fqs=105807
[  919.030295]  (detected by 1, t=225825 jiffies, g=1561, q=3496)
[  919.036109] Task dump for CPU 0:
[  919.039321] kworker/0:1     R  running task        0    30      2 0x00000008
[  919.046359] Workqueue: events set_brightness_delayed
[  919.051302] Call Trace:
[  919.053738] [<ffffffe000930d92>] __schedule+0x194/0x4de
[  982.035783] rcu: INFO: rcu_sched detected stalls on CPUs/tasks:
[  982.040923] rcu:     0-...0: (0 ticks this GP)
idle=7d2/1/0x4000000000000002 softirq=1424/1424 fqs=113325
[  982.050294]  (detected by 1, t=241580 jiffies, g=1561, q=3509)
[  982.056108] Task dump for CPU 0:
[  982.059321] kworker/0:1     R  running task        0    30      2 0x00000008
[  982.066359] Workqueue: events set_brightness_delayed
[  982.071302] Call Trace:
[  982.073739] [<ffffffe000930d92>] __schedule+0x194/0x4de
[..]

After applying this patch, the CPU hang issue can be fixed.

Signed-off-by: Greentime Hu <greentime.hu@...ive.com>
---
 drivers/irqchip/irq-sifive-plic.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/irqchip/irq-sifive-plic.c b/drivers/irqchip/irq-sifive-plic.c
index 4cc8a2657a6d..8a673d9cff69 100644
--- a/drivers/irqchip/irq-sifive-plic.c
+++ b/drivers/irqchip/irq-sifive-plic.c
@@ -183,10 +183,14 @@ static int plic_irqdomain_map(struct irq_domain *d, unsigned int irq,
 			      irq_hw_number_t hwirq)
 {
 	struct plic_priv *priv = d->host_data;
+	struct irq_data *irqd;
 
 	irq_domain_set_info(d, irq, hwirq, &plic_chip, d->host_data,
 			    handle_fasteoi_irq, NULL, NULL);
 	irq_set_noprobe(irq);
+	irqd = irq_get_irq_data(irq);
+	irqd_set_single_target(irqd);
+	irqd_set_affinity_on_activate(irqd);
 	irq_set_affinity(irq, &priv->lmask);
 	return 0;
 }
-- 
2.28.0