Messages in this thread Patch in this message | | | Date | Mon, 27 Feb 2017 09:12:00 -0800 | From | Sodagudi Prasad <> | Subject | Re: Schedule affinity_notify work while migrating IRQs during hot plug |
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On 2017-02-21 12:59, Sodagudi Prasad wrote: > Hi Thomas, > > Currently irq_set_affinity() is called to migrate irqs from > migrate_one_irq() > during cpu hot plug and clients which are interested to know the irq > affinity change > not getting notified > > take_cpu_down () --> __cpu_disable() --> > irq_migrate_all_off_this_cpu(); > > irq_set_affinity() is changing the IRQ affinity at chip level > but it is not notifying the affinity_notify work. >
Hi Thomas and All,
I could see that in the 3.10 kernel irq affinity notifiers are getting called when a core getting hot plugged. But in later kernel versions api used to change affinity was changed from irq_set_affinity_locked() to irq_do_set_affinity(), so irq notifiers are not getting called when a core hot plugged. https://git.kernel.org/cgit/linux/kernel/git/stable/linux-stable.git/tree/kernel/irq/manage.c?id=refs/tags/v3.10.105#n201
In latest kernel following path is executed to migrate IRQs. irq_migrate_all_off_this_cpu() --> migrate_one_irq() -> irq_do_set_affinity().
As I mentioned above, irq_set_affinity_locked() notifies all clients drivers, which are registered for IRQ affinity change but irq_do_set_affinity() API just changes the affinity at irq chip level but does not notify the clients drivers. I am not sure whether it is just a miss during IRQ framework refactor or intentionally done like this. Can you please check whether following code change make sense or not?
So I am thinking that, adding following sched_work() would notify clients.
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; }
> How about below change, so that clients drivers gets notified about > irq affinity changes? > --- 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; > > With this change, notifications of IRQ affinity gets executed and > notified > to client drivers.
-Thanks, Prasad -- The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum, Linux Foundation Collaborative Project
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