linux-kernel - [PATCH RFC] irqchip: gic-v3: Support forced cpu irq affinity setting

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Date:   Tue, 08 Aug 2017 14:34:53 +0530
From:   Alim Akhtar <alim.akhtar@...sung.com>
To:     tglx@...utronix.de, linux-kernel@...r.kernel.org
Cc:     jason@...edaemon.net, marc.zyngier@....com,
        linux-arm-kernel@...ts.infradead.org, shaik.ameer@...sung.com,
        aswani.reddy@...sung.com, abhinav.k@...sung.com,
        alim.akhtar@...il.com, arjun.kv@...sung.com
Subject: [PATCH RFC] irqchip: gic-v3: Support forced cpu irq affinity
 setting

Skip check for online cpu mask when setting irq affinity of per cpu timer
during early startup of not yet online cpu.

Signed-off-by: Shaik Ameer Basha <shaik.ameer@...sung.com>
Signed-off-by: Aswani Reddy <aswani.reddy@...sung.com>
Signed-off-by: Alim Akhtar <alim.akhtar@...sung.com>
---
 drivers/irqchip/irq-gic-v3.c | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

Currently when non boot CPUs comes up and if setting of IRQ affinity gets called
before cpu online status gets updated, gic_mpidr_to_affinity() returns
undesirable cpu number. Using __force__ flag ignore cpu_online_mask and setup
the intended cpu affinity for the irq.

The same approch is used in gicv2 
(commit: ffde1de64012c: irqchip: Gic: Support forced affinity setting)

diff --git a/drivers/irqchip/irq-gic-v3.c b/drivers/irqchip/irq-gic-v3.c
index dbffb7a..c238c64 100644
--- a/drivers/irqchip/irq-gic-v3.c
+++ b/drivers/irqchip/irq-gic-v3.c
@@ -640,11 +640,16 @@ static void gic_smp_init(void)
 static int gic_set_affinity(struct irq_data *d, const struct cpumask *mask_val,
 			    bool force)
 {
-	unsigned int cpu = cpumask_any_and(mask_val, cpu_online_mask);
+	unsigned int cpu;
 	void __iomem *reg;
 	int enabled;
 	u64 val;
 
+	if (!force)
+		cpu = cpumask_any_and(mask_val, cpu_online_mask);
+	else
+		cpu = cpumask_first(mask_val);
+
 	if (cpu >= nr_cpu_ids)
 		return -EINVAL;
 
-- 
2.7.4