Re: [PATCH] mmc: meson-gx: remove IRQF_ONESHOT

[Brad Harper]

On 7/10/2020 10:32 pm, Jerome Brunet wrote:
> With arm64 defconfig on Khadas vim3, no obvious regression. Looks good.
>
> Tested-by: Jerome Brunet <jbrunet@xxxxxxxxxxxx>
>
> I did not test with RT. Brad, Could you let us know is Thomas's patch
> works for you ? Thx
There was a merge conflict in applying against v5.9-rc8-rt12 with
particular this patch:
https://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-rt-devel.git/commit/kernel/irq/manage.c?h=linux-5.9.y-rt&id=18df00ef0b2b1513dc8f1a9ed26b11fff2261c30

I did manage to add the patch after attempting to resolve the conflict
which solves the deadlock issue I am seeing with mmc and works fine during
testing (a kernel compilation on preempt_rt configured kernel).

irq_thread in /kernel/irq/manage.c Looks like this (not 100% sure I
should have placed the irq_finalize_oneshot before
add_interrupt_randomness).

Based on this I can provide

Tested-by: Brad Harper <bjharper@xxxxxxxxx>

---
static int irq_thread(void *data)
{
        struct callback_head on_exit_work;
        struct irqaction *action = data;
        struct irq_desc *desc = irq_to_desc(action->irq);
        irqreturn_t (*handler_fn)(struct irq_desc *desc,
                        struct irqaction *action);

        if (force_irqthreads && test_bit(IRQTF_FORCED_THREAD,
&action->thread_flags))
                handler_fn = irq_forced_thread_fn;
        else
                handler_fn = irq_thread_fn;

        init_task_work(&on_exit_work, irq_thread_dtor);
        task_work_add(current, &on_exit_work, false);

        irq_thread_check_affinity(desc, action);

        while (!irq_wait_for_interrupt(action)) {
                irqreturn_t action_ret;

                irq_thread_check_affinity(desc, action);

                action_ret = handler_fn(desc, action);
                if (action_ret == IRQ_HANDLED)
                        atomic_inc(&desc->threads_handled);

                if (action_ret == IRQ_WAKE_THREAD)
                        irq_wake_secondary(desc, action);

                irq_finalize_oneshot(desc, action);

                if (IS_ENABLED(CONFIG_PREEMPT_RT)) {
                       migrate_disable();
                       add_interrupt_randomness(action->irq, 0,
                                desc->random_ip ^ (unsigned long) action);
                       migrate_enable();
                }
                wake_threads_waitq(desc);
        }

        /*
         * This is the regular exit path. __free_irq() is stopping the
         * thread via kthread_stop() after calling
         * synchronize_hardirq(). So neither IRQTF_RUNTHREAD nor the
         * oneshot mask bit can be set.
         */
        task_work_cancel(current, irq_thread_dtor);
        return 0;
}

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