Hi Marc,

On Friday, 18 August 2017 08:37:03 PDT Marc Zyngier wrote:

On 13/08/17 05:36, Paul Burton wrote:

quoted

Define the pcpu_masks variable using the kernel's standard per-cpu
variable support, rather than an open-coded array of structs containing
bitmaps.

Signed-off-by: Paul Burton <redacted>
Cc: Jason Cooper <redacted>
Cc: Marc Zyngier <redacted>
Cc: Ralf Baechle <redacted>
Cc: Thomas Gleixner <redacted>
Cc: linux-mips@linux-mips.org
---

 drivers/irqchip/irq-mips-gic.c | 17 ++++++++---------
 1 file changed, 8 insertions(+), 9 deletions(-)

diff --git a/drivers/irqchip/irq-mips-gic.c

b/drivers/irqchip/irq-mips-gic.c index feff4bf97577..00153231376a 100644

--- a/drivers/irqchip/irq-mips-gic.c
+++ b/drivers/irqchip/irq-mips-gic.c

@@ -13,6 +13,7 @@

 #include <linux/irq.h>
 #include <linux/irqchip.h>
 #include <linux/of_address.h>

+#include <linux/percpu.h>

 #include <linux/sched.h>
 #include <linux/smp.h>

@@ -23,6 +24,7 @@

 #include <dt-bindings/interrupt-controller/mips-gic.h>
 
 #define GIC_MAX_INTRS		256

+#define GIC_MAX_LONGS		BITS_TO_LONGS(GIC_MAX_INTRS)

 /* Add 2 to convert GIC CPU pin to core interrupt */
 #define GIC_CPU_PIN_OFFSET	2

@@ -40,11 +42,8 @@

 void __iomem *mips_gic_base;

-struct gic_pcpu_mask {
-	DECLARE_BITMAP(pcpu_mask, GIC_MAX_INTRS);
-};
+DEFINE_PER_CPU_READ_MOSTLY(unsigned long[GIC_MAX_LONGS], pcpu_masks);

-static struct gic_pcpu_mask pcpu_masks[NR_CPUS];

 static DEFINE_SPINLOCK(gic_lock);
 static struct irq_domain *gic_irq_domain;
 static struct irq_domain *gic_ipi_domain;

@@ -137,7 +136,7 @@ static void gic_handle_shared_int(bool chained)

 	DECLARE_BITMAP(intrmask, GIC_MAX_INTRS);
 	
 	/* Get per-cpu bitmaps */

-	pcpu_mask = pcpu_masks[smp_processor_id()].pcpu_mask;
+	pcpu_mask = this_cpu_ptr(pcpu_masks);

 	if (mips_cm_is64) {
 	
 		__ioread64_copy(pending, addr_gic_pend(),

@@ -254,8 +253,8 @@ static int gic_set_affinity(struct irq_data *d, const

struct cpumask *cpumask,> 
 	/* Update the pcpu_masks */
 	for (i = 0; i < min(gic_vpes, NR_CPUS); i++)

Is there any case where gic_vpes is not equal to nr_cpus?

Yes - if the kernel is built with CONFIG_NR_CPUS set to something other than 
the actual number of VPs (Virtual Processors, ie. hardware threads) in the 
system. (VPE, or Virtual Processing Element, is a roughly equivalent term used 
in older revisions of the MIPS architecture).

To be honest I suspect gic_vpes should go away, and for example in this case 
we should juse use for_each_possible_cpu(). The use of gic_vpes here was added 
by commit 2a0787051182 ("irqchip/mips-gic: Use gic_vpes instead of NR_CPUS") 
but it doesn't really do a good job of explaining why - I suspect Qais felt it 
was an optimisation, but that's debatable.

This code will need adjusting to add multi-cluster support, which is my 
ultimate goal here, anyway. So that'll be one of the next things for me to 
tackle.

Thanks,
    Paul

quoted

-		clear_bit(irq, pcpu_masks[i].pcpu_mask);
-	set_bit(irq, pcpu_masks[cpumask_first(&tmp)].pcpu_mask);
+		clear_bit(irq, per_cpu_ptr(pcpu_masks, i));
+	set_bit(irq, per_cpu_ptr(pcpu_masks, cpumask_first(&tmp)));

 	cpumask_copy(irq_data_get_affinity_mask(d), cpumask);
 	spin_unlock_irqrestore(&gic_lock, flags);

@@ -416,8 +415,8 @@ static int gic_shared_irq_domain_map(struct irq_domain

*d, unsigned int virq,> 
 	write_gic_map_pin(intr, GIC_MAP_PIN_MAP_TO_PIN | gic_cpu_pin);
 	write_gic_map_vp(intr, BIT(mips_cm_vp_id(vpe)));
 	for (i = 0; i < min(gic_vpes, NR_CPUS); i++)

-		clear_bit(intr, pcpu_masks[i].pcpu_mask);
-	set_bit(intr, pcpu_masks[vpe].pcpu_mask);
+		clear_bit(intr, per_cpu_ptr(pcpu_masks, i));
+	set_bit(intr, per_cpu_ptr(pcpu_masks, vpe));

 	spin_unlock_irqrestore(&gic_lock, flags);
 	
 	return 0;

Thanks,

	M.