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irq/irq_sim: Store multiple interrupt offsets in a bitmap

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Two threads can try to fire the irq_sim with different offsets and will
end up fighting for the irq_work asignment. Thomas Gleixner suggested a
solution based on a bitfield where we set a bit for every offset
associated with an interrupt that should be fired and then iterate over
all set bits in the interrupt handler.

This is a slightly modified solution using a bitmap so that we don't
impose a limit on the number of interrupts one can allocate with
irq_sim.

Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Bartosz Golaszewski <brgl@bgdev.pl>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
This commit is contained in:
Bartosz Golaszewski 2018-11-09 18:21:32 +01:00 committed by Marc Zyngier
parent 81b1e6e6a8
commit 06459901d5
2 changed files with 22 additions and 3 deletions
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2
include/linux/irq_sim.h
View File

@ -16,7 +16,7 @@
struct irq_sim_work_ctx {
struct irq_work work;
int irq;
unsigned long *pending;
};
struct irq_sim_irq_ctx {

23
kernel/irq/irq_sim.c
View File

@ -34,9 +34,20 @@ static struct irq_chip irq_sim_irqchip = {
static void irq_sim_handle_irq(struct irq_work *work)
{
struct irq_sim_work_ctx *work_ctx;
unsigned int offset = 0;
struct irq_sim *sim;
int irqnum;
work_ctx = container_of(work, struct irq_sim_work_ctx, work);
handle_simple_irq(irq_to_desc(work_ctx->irq));
sim = container_of(work_ctx, struct irq_sim, work_ctx);
while (!bitmap_empty(work_ctx->pending, sim->irq_count)) {
offset = find_next_bit(work_ctx->pending,
sim->irq_count, offset);
clear_bit(offset, work_ctx->pending);
irqnum = irq_sim_irqnum(sim, offset);
handle_simple_irq(irq_to_desc(irqnum));
}
}
/**
@ -63,6 +74,13 @@ int irq_sim_init(struct irq_sim *sim, unsigned int num_irqs)
return sim->irq_base;
}
sim->work_ctx.pending = bitmap_zalloc(num_irqs, GFP_KERNEL);
if (!sim->work_ctx.pending) {
kfree(sim->irqs);
irq_free_descs(sim->irq_base, num_irqs);
return -ENOMEM;
}
for (i = 0; i < num_irqs; i++) {
sim->irqs[i].irqnum = sim->irq_base + i;
sim->irqs[i].enabled = false;
@ -89,6 +107,7 @@ EXPORT_SYMBOL_GPL(irq_sim_init);
void irq_sim_fini(struct irq_sim *sim)
{
irq_work_sync(&sim->work_ctx.work);
bitmap_free(sim->work_ctx.pending);
irq_free_descs(sim->irq_base, sim->irq_count);
kfree(sim->irqs);
}
@ -143,7 +162,7 @@ EXPORT_SYMBOL_GPL(devm_irq_sim_init);
void irq_sim_fire(struct irq_sim *sim, unsigned int offset)
{
if (sim->irqs[offset].enabled) {
sim->work_ctx.irq = irq_sim_irqnum(sim, offset);
set_bit(offset, sim->work_ctx.pending);
irq_work_queue(&sim->work_ctx.work);
}
}