linux-kernel - Re: [PATCH] irq/irq_sim: store multiple interrupt offsets in a bitmap

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Date:   Tue, 11 Dec 2018 16:39:48 +0100
From:   Bartosz Golaszewski <brgl@...ev.pl>
To:     Marc Zyngier <marc.zyngier@....com>
Cc:     Thomas Gleixner <tglx@...utronix.de>,
        Uwe Kleine-König 
        <u.kleine-koenig@...gutronix.de>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] irq/irq_sim: store multiple interrupt offsets in a bitmap

wt., 11 gru 2018 o 15:42 Marc Zyngier <marc.zyngier@....com> napisał(a):
>
> 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/ .
>

Your e-mail doesn't pop up with get_maintainer on this patch. That's
why you didn't get it initially.

Bart