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Message-ID: <204b38d9-7658-f21d-3153-e1d9db749550@arm.com>
Date: Tue, 11 Dec 2018 14:41:57 +0000
From: Marc Zyngier <marc.zyngier@....com>
To: Bartosz Golaszewski <brgl@...ev.pl>,
Thomas Gleixner <tglx@...utronix.de>,
Uwe Kleine-König <u.kleine-koenig@...gutronix.de>
Cc: Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] irq/irq_sim: store multiple interrupt offsets in a bitmap
On 11/12/2018 14:02, Bartosz Golaszewski wrote:
> pt., 9 lis 2018 o 18:21 Bartosz Golaszewski <brgl@...ev.pl> napisał(a):
>>
>> 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@...utronix.de>
>> Signed-off-by: Bartosz Golaszewski <brgl@...ev.pl>
>> ---
>> include/linux/irq_sim.h | 2 +-
>> kernel/irq/irq_sim.c | 23 +++++++++++++++++++++--
>> 2 files changed, 22 insertions(+), 3 deletions(-)
>>
>> diff --git a/include/linux/irq_sim.h b/include/linux/irq_sim.h
>> index 630a57e55db6..4500d453a63e 100644
>> --- a/include/linux/irq_sim.h
>> +++ b/include/linux/irq_sim.h
>> @@ -16,7 +16,7 @@
>>
>> struct irq_sim_work_ctx {
>> struct irq_work work;
>> - int irq;
>> + unsigned long *pending;
>> };
>>
>> struct irq_sim_irq_ctx {
>> diff --git a/kernel/irq/irq_sim.c b/kernel/irq/irq_sim.c
>> index dd20d0d528d4..98a20e1594ce 100644
>> --- a/kernel/irq/irq_sim.c
>> +++ b/kernel/irq/irq_sim.c
>> @@ -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);
>> }
>> }
>> --
>> 2.19.1
>>
>
> Ping and Cc'ing Marc Zyngier. Any chance of getting this in for 4.21?
Bizarrely, I can't find any trace of this patch in my Inbox. I've now
cherry-picked from https://lore.kernel.org/patchwork/patch/1009297/ .
Thanks,
M.
--
Jazz is not dead. It just smells funny...
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