[v2,3/4] irq: Allow multiple clients to register for irq affinity notification

Message ID 1407945689-18494-4-git-send-email-lina.iyer@linaro.org
State New
Headers show

Commit Message

Lina Iyer Aug. 13, 2014, 4:01 p.m.
The current implementation allows only a single notification callback
whenever the IRQ's SMP affinity is changed. Adding a second notification
punts the existing notifier function out of registration.

Add a list of notifiers, allowing multiple clients to register for irq
affinity notifications.

Signed-off-by: Lina Iyer <lina.iyer@linaro.org>
---
 drivers/infiniband/hw/qib/qib_iba7322.c |  4 +-
 include/linux/interrupt.h               | 12 ++++-
 include/linux/irq.h                     |  1 +
 include/linux/irqdesc.h                 |  6 ++-
 kernel/irq/irqdesc.c                    |  1 +
 kernel/irq/manage.c                     | 85 ++++++++++++++++++++++-----------
 lib/cpu_rmap.c                          |  2 +-
 7 files changed, 74 insertions(+), 37 deletions(-)

Comments

Kevin Hilman Aug. 19, 2014, 12:04 a.m. | #1
Lina Iyer <lina.iyer@linaro.org> writes:

> The current implementation allows only a single notification callback
> whenever the IRQ's SMP affinity is changed. Adding a second notification
> punts the existing notifier function out of registration.
>
> Add a list of notifiers, allowing multiple clients to register for irq
> affinity notifications.

nit: the changelog describes "what", but doesn't answer "why?"  You
address it a bit in the cover letter, but it should probably be spelled out
here since this patch will likely need to be separated from this series
and taken via the IRQ core maintiners.

Kevin
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Lina Iyer Aug. 19, 2014, 12:17 a.m. | #2
On Mon, Aug 18, 2014 at 05:04:22PM -0700, Kevin Hilman wrote:
>Lina Iyer <lina.iyer@linaro.org> writes:
>
>> The current implementation allows only a single notification callback
>> whenever the IRQ's SMP affinity is changed. Adding a second notification
>> punts the existing notifier function out of registration.
>>
>> Add a list of notifiers, allowing multiple clients to register for irq
>> affinity notifications.
>
>nit: the changelog describes "what", but doesn't answer "why?"  You
>address it a bit in the cover letter, but it should probably be spelled out
>here since this patch will likely need to be separated from this series
>and taken via the IRQ core maintiners.
Good point. I will amend it.

>
>Kevin
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Patch

diff --git a/drivers/infiniband/hw/qib/qib_iba7322.c b/drivers/infiniband/hw/qib/qib_iba7322.c
index a7eb325..62cb77d 100644
--- a/drivers/infiniband/hw/qib/qib_iba7322.c
+++ b/drivers/infiniband/hw/qib/qib_iba7322.c
@@ -3345,9 +3345,7 @@  static void reset_dca_notifier(struct qib_devdata *dd, struct qib_msix_entry *m)
 		"Disabling notifier on HCA %d irq %d\n",
 		dd->unit,
 		m->msix.vector);
-	irq_set_affinity_notifier(
-		m->msix.vector,
-		NULL);
+	irq_release_affinity_notifier(m->notifier);
 	m->notifier = NULL;
 }
 
diff --git a/include/linux/interrupt.h b/include/linux/interrupt.h
index 698ad05..c1e227c 100644
--- a/include/linux/interrupt.h
+++ b/include/linux/interrupt.h
@@ -203,7 +203,7 @@  static inline int check_wakeup_irqs(void) { return 0; }
  * struct irq_affinity_notify - context for notification of IRQ affinity changes
  * @irq:		Interrupt to which notification applies
  * @kref:		Reference count, for internal use
- * @work:		Work item, for internal use
+ * @list:		Add to the notifier list, for internal use
  * @notify:		Function to be called on change.  This will be
  *			called in process context.
  * @release:		Function to be called on release.  This will be
@@ -214,7 +214,7 @@  static inline int check_wakeup_irqs(void) { return 0; }
 struct irq_affinity_notify {
 	unsigned int irq;
 	struct kref kref;
-	struct work_struct work;
+	struct list_head list;
 	void (*notify)(struct irq_affinity_notify *, const cpumask_t *mask);
 	void (*release)(struct kref *ref);
 };
@@ -265,6 +265,8 @@  extern int irq_set_affinity_hint(unsigned int irq, const struct cpumask *m);
 extern int
 irq_set_affinity_notifier(unsigned int irq, struct irq_affinity_notify *notify);
 
+extern int
+irq_release_affinity_notifier(struct irq_affinity_notify *notify);
 #else /* CONFIG_SMP */
 
 static inline int irq_set_affinity(unsigned int irq, const struct cpumask *m)
@@ -295,6 +297,12 @@  irq_set_affinity_notifier(unsigned int irq, struct irq_affinity_notify *notify)
 {
 	return 0;
 }
+
+static inline int
+irq_release_affinity_notifier(struct irq_affinity_notify *notify)
+{
+	return 0;
+}
 #endif /* CONFIG_SMP */
 
 /*
diff --git a/include/linux/irq.h b/include/linux/irq.h
index 62af592..2634a48 100644
--- a/include/linux/irq.h
+++ b/include/linux/irq.h
@@ -20,6 +20,7 @@ 
 #include <linux/errno.h>
 #include <linux/topology.h>
 #include <linux/wait.h>
+#include <linux/list.h>
 
 #include <asm/irq.h>
 #include <asm/ptrace.h>
diff --git a/include/linux/irqdesc.h b/include/linux/irqdesc.h
index 472c021..db3509e 100644
--- a/include/linux/irqdesc.h
+++ b/include/linux/irqdesc.h
@@ -31,7 +31,8 @@  struct irq_desc;
  * @threads_handled_last: comparator field for deferred spurious detection of theraded handlers
  * @lock:		locking for SMP
  * @affinity_hint:	hint to user space for preferred irq affinity
- * @affinity_notify:	context for notification of affinity changes
+ * @affinity_notify:	list of notification clients for affinity changes
+ * @affinity_work:	Work queue for handling affinity change notifications
  * @pending_mask:	pending rebalanced interrupts
  * @threads_oneshot:	bitfield to handle shared oneshot threads
  * @threads_active:	number of irqaction threads currently running
@@ -60,7 +61,8 @@  struct irq_desc {
 	struct cpumask		*percpu_enabled;
 #ifdef CONFIG_SMP
 	const struct cpumask	*affinity_hint;
-	struct irq_affinity_notify *affinity_notify;
+	struct list_head	affinity_notify;
+	struct work_struct	affinity_work;
 #ifdef CONFIG_GENERIC_PENDING_IRQ
 	cpumask_var_t		pending_mask;
 #endif
diff --git a/kernel/irq/irqdesc.c b/kernel/irq/irqdesc.c
index 1487a12..c95e1f3 100644
--- a/kernel/irq/irqdesc.c
+++ b/kernel/irq/irqdesc.c
@@ -91,6 +91,7 @@  static void desc_set_defaults(unsigned int irq, struct irq_desc *desc, int node,
 	for_each_possible_cpu(cpu)
 		*per_cpu_ptr(desc->kstat_irqs, cpu) = 0;
 	desc_smp_init(desc, node);
+	INIT_LIST_HEAD(&desc->affinity_notify);
 }
 
 int nr_irqs = NR_IRQS;
diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c
index 88657d7..99fc0e7 100644
--- a/kernel/irq/manage.c
+++ b/kernel/irq/manage.c
@@ -209,10 +209,9 @@  int irq_set_affinity_locked(struct irq_data *data, const struct cpumask *mask,
 		irq_copy_pending(desc, mask);
 	}
 
-	if (desc->affinity_notify) {
-		kref_get(&desc->affinity_notify->kref);
-		schedule_work(&desc->affinity_notify->work);
-	}
+	if (!list_empty(&desc->affinity_notify))
+		schedule_work(&desc->affinity_work);
+
 	irqd_set(data, IRQD_AFFINITY_SET);
 
 	return ret;
@@ -248,14 +247,14 @@  EXPORT_SYMBOL_GPL(irq_set_affinity_hint);
 
 static void irq_affinity_notify(struct work_struct *work)
 {
-	struct irq_affinity_notify *notify =
-		container_of(work, struct irq_affinity_notify, work);
-	struct irq_desc *desc = irq_to_desc(notify->irq);
+	struct irq_desc *desc =
+			container_of(work, struct irq_desc, affinity_work);
 	cpumask_var_t cpumask;
 	unsigned long flags;
+	struct irq_affinity_notify *notify;
 
 	if (!desc || !alloc_cpumask_var(&cpumask, GFP_KERNEL))
-		goto out;
+		return;
 
 	raw_spin_lock_irqsave(&desc->lock, flags);
 	if (irq_move_pending(&desc->irq_data))
@@ -264,11 +263,20 @@  static void irq_affinity_notify(struct work_struct *work)
 		cpumask_copy(cpumask, desc->irq_data.affinity);
 	raw_spin_unlock_irqrestore(&desc->lock, flags);
 
-	notify->notify(notify, cpumask);
+	list_for_each_entry(notify, &desc->affinity_notify, list) {
+		/**
+		 * Check and get the kref only if the kref has not been
+		 * released by now. Its possible that the reference count
+		 * is already 0, we dont want to notify those if they are
+		 * already released.
+		 */
+		if (!kref_get_unless_zero(&notify->kref))
+			continue;
+		notify->notify(notify, cpumask);
+		kref_put(&notify->kref, notify->release);
+	}
 
 	free_cpumask_var(cpumask);
-out:
-	kref_put(&notify->kref, notify->release);
 }
 
 /**
@@ -286,34 +294,50 @@  int
 irq_set_affinity_notifier(unsigned int irq, struct irq_affinity_notify *notify)
 {
 	struct irq_desc *desc = irq_to_desc(irq);
-	struct irq_affinity_notify *old_notify;
 	unsigned long flags;
 
-	/* The release function is promised process context */
-	might_sleep();
-
 	if (!desc)
 		return -EINVAL;
 
-	/* Complete initialisation of *notify */
-	if (notify) {
-		notify->irq = irq;
-		kref_init(&notify->kref);
-		INIT_WORK(&notify->work, irq_affinity_notify);
+	if (!notify) {
+		WARN("%s called with NULL notifier - use irq_release_affinity_notifier function instead.\n",
+				__func__);
+		return -EINVAL;
 	}
 
+	notify->irq = irq;
+	kref_init(&notify->kref);
+	INIT_LIST_HEAD(&notify->list);
 	raw_spin_lock_irqsave(&desc->lock, flags);
-	old_notify = desc->affinity_notify;
-	desc->affinity_notify = notify;
+	list_add(&notify->list, &desc->affinity_notify);
 	raw_spin_unlock_irqrestore(&desc->lock, flags);
 
-	if (old_notify)
-		kref_put(&old_notify->kref, old_notify->release);
-
 	return 0;
 }
 EXPORT_SYMBOL_GPL(irq_set_affinity_notifier);
 
+/**
+ *	irq_release_affinity_notifier - Remove us from notifications
+ *	@notify: Context for notification
+ */
+int irq_release_affinity_notifier(struct irq_affinity_notify *notify)
+{
+	struct irq_desc *desc;
+	unsigned long flags;
+
+	if (!notify)
+		return -EINVAL;
+
+	desc = irq_to_desc(notify->irq);
+	raw_spin_lock_irqsave(&desc->lock, flags);
+	list_del(&notify->list);
+	raw_spin_unlock_irqrestore(&desc->lock, flags);
+	kref_put(&notify->kref, notify->release);
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(irq_release_affinity_notifier);
+
 #ifndef CONFIG_AUTO_IRQ_AFFINITY
 /*
  * Generic version of the affinity autoselector.
@@ -348,6 +372,8 @@  setup_affinity(unsigned int irq, struct irq_desc *desc, struct cpumask *mask)
 		if (cpumask_intersects(mask, nodemask))
 			cpumask_and(mask, mask, nodemask);
 	}
+	INIT_LIST_HEAD(&desc->affinity_notify);
+	INIT_WORK(&desc->affinity_work, irq_affinity_notify);
 	irq_do_set_affinity(&desc->irq_data, mask, false);
 	return 0;
 }
@@ -1414,14 +1440,15 @@  EXPORT_SYMBOL_GPL(remove_irq);
 void free_irq(unsigned int irq, void *dev_id)
 {
 	struct irq_desc *desc = irq_to_desc(irq);
+	struct irq_affinity_notify *notify;
 
 	if (!desc || WARN_ON(irq_settings_is_per_cpu_devid(desc)))
 		return;
 
-#ifdef CONFIG_SMP
-	if (WARN_ON(desc->affinity_notify))
-		desc->affinity_notify = NULL;
-#endif
+	WARN_ON(!list_empty(&desc->affinity_notify));
+
+	list_for_each_entry(notify, &desc->affinity_notify, list)
+		kref_put(&notify->kref, notify->release);
 
 	chip_bus_lock(desc);
 	kfree(__free_irq(irq, dev_id));
diff --git a/lib/cpu_rmap.c b/lib/cpu_rmap.c
index 4f134d8..0c8da50 100644
--- a/lib/cpu_rmap.c
+++ b/lib/cpu_rmap.c
@@ -235,7 +235,7 @@  void free_irq_cpu_rmap(struct cpu_rmap *rmap)
 
 	for (index = 0; index < rmap->used; index++) {
 		glue = rmap->obj[index];
-		irq_set_affinity_notifier(glue->notify.irq, NULL);
+		irq_release_affinity_notifier(&glue->notify);
 	}
 
 	cpu_rmap_put(rmap);