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SubjectRe: Schedule affinity_notify work while migrating IRQs during hot plug
On 2017-02-27 09:21, Thomas Gleixner wrote:
> On Mon, 27 Feb 2017, Sodagudi Prasad wrote:
>> So I am thinking that, adding following sched_work() would notify
>> clients.
>
> And break the world and some more.
>
>> diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
>> index 6b66959..5e4766b 100644
>> --- a/kernel/irq/manage.c
>> +++ b/kernel/irq/manage.c
>> @@ -207,6 +207,7 @@ int irq_do_set_affinity(struct irq_data *data,
>> const
>> struct cpumask *mask,
>> case IRQ_SET_MASK_OK_DONE:
>> cpumask_copy(desc->irq_common_data.affinity, mask);
>> case IRQ_SET_MASK_OK_NOCOPY:
>> + schedule_work(&desc->affinity_notify->work);
>> irq_set_thread_affinity(desc);
>> ret = 0;
>
> You cannot do that unconditionally and just slap that schedule_work()
> call
> into the code. Aside of that schedule_work() would be invoked twice for
> all
> calls which come via irq_set_affinity_locked() ....
Hi Tglx,

Yes. I agree with you, schedule_work() gets invoked twice with previous
change.

How about calling irq_set_notify_locked() instead of
irq_do_set_notify()?

diff --git a/kernel/irq/cpuhotplug.c b/kernel/irq/cpuhotplug.c
index 011f8c4..e8ce0db 100644
--- a/kernel/irq/cpuhotplug.c
+++ b/kernel/irq/cpuhotplug.c
@@ -18,8 +18,8 @@ static bool migrate_one_irq(struct irq_desc *desc)
{
struct irq_data *d = irq_desc_get_irq_data(desc);
const struct cpumask *affinity = d->common->affinity;
- struct irq_chip *c;
bool ret = false;
+ int r;

/*
* If this is a per-CPU interrupt, or the affinity does not
@@ -34,15 +34,10 @@ static bool migrate_one_irq(struct irq_desc *desc)
ret = true;
}

- c = irq_data_get_irq_chip(d);
- if (!c->irq_set_affinity) {
- pr_debug("IRQ%u: unable to set affinity\n", d->irq);
- } else {
- int r = irq_do_set_affinity(d, affinity, false);
- if (r)
- pr_warn_ratelimited("IRQ%u: set affinity
failed(%d).\n",
+ r = irq_set_affinity_locked(d, affinity, false);
+ if (r)
+ pr_warn_ratelimited("IRQ%u: set affinity failed(%d).\n",
d->irq, r);
- }

return ret;

-Thanks, Prasad
>
> Thanks,
>
> tglx

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