[V6,1/3] genirq: add device_has_managed_msi_irq

Commit Message

Ming Lei July 22, 2021, 9:52 a.m. UTC

irq vector allocation with managed affinity may be used by driver, and
blk-mq needs this info for draining queue because genirq core will shutdown
managed irq when all CPUs in the affinity mask are offline.

The info of using managed irq is often produced by drivers, and it is
consumed by blk-mq, so different subsystems are involved in this info flow.

Address this issue by adding one helper of device_has_managed_msi_irq()
which is suggested by John Garry.

Suggested-by: John Garry <[e-mail]>
Signed-off-by: Ming Lei <[e-mail]>
---
 include/linux/msi.h |  5 +++++
 kernel/irq/msi.c    | 18 ++++++++++++++++++
 2 files changed, 23 insertions(+)

Comments

Christoph Hellwig July 22, 2021, 1:05 p.m. UTC | #1

On Thu, Jul 22, 2021 at 05:52:44PM +0800, Ming Lei wrote:
> irq vector allocation with managed affinity may be used by driver, and
> blk-mq needs this info for draining queue because genirq core will shutdown
> managed irq when all CPUs in the affinity mask are offline.
> 
> The info of using managed irq is often produced by drivers, and it is
> consumed by blk-mq, so different subsystems are involved in this info flow.
> 
> Address this issue by adding one helper of device_has_managed_msi_irq()
> which is suggested by John Garry.

This implies non-MSI irqs can't be managed, which is true right now.
If the irq maintaines are fine with that:

Reviewed-by: Christoph Hellwig <[e-mail]>

Patch

diff --git a/include/linux/msi.h b/include/linux/msi.h
index 6aff469e511d..2d0f3962d3c3 100644
--- a/include/linux/msi.h
+++ b/include/linux/msi.h
@@ -59,10 +59,15 @@  struct platform_msi_priv_data;
 void __get_cached_msi_msg(struct msi_desc *entry, struct msi_msg *msg);
 #ifdef CONFIG_GENERIC_MSI_IRQ
 void get_cached_msi_msg(unsigned int irq, struct msi_msg *msg);
+bool device_has_managed_msi_irq(struct device *dev);
 #else
 static inline void get_cached_msi_msg(unsigned int irq, struct msi_msg *msg)
 {
 }
+static inline bool device_has_managed_msi_irq(struct device *dev)
+{
+	return false;
+}
 #endif
 
 typedef void (*irq_write_msi_msg_t)(struct msi_desc *desc,
diff --git a/kernel/irq/msi.c b/kernel/irq/msi.c
index c41965e348b5..01aae22246c8 100644
--- a/kernel/irq/msi.c
+++ b/kernel/irq/msi.c
@@ -69,6 +69,24 @@  void get_cached_msi_msg(unsigned int irq, struct msi_msg *msg)
 }
 EXPORT_SYMBOL_GPL(get_cached_msi_msg);
 
+/**
+ * device_has_managed_msi_irq - Query if device has managed irq entry
+ * @dev:	Pointer to the device for which we want to query
+ *
+ * Return true if there is managed irq vector allocated on this device
+ */
+bool device_has_managed_msi_irq(struct device *dev)
+{
+	struct msi_desc *desc;
+
+	for_each_msi_entry(desc, dev) {
+		if (desc->affinity && desc->affinity->is_managed)
+			return true;
+	}
+	return false;
+}
+EXPORT_SYMBOL_GPL(device_has_managed_msi_irq);
+
 #ifdef CONFIG_GENERIC_MSI_IRQ_DOMAIN
 static inline void irq_chip_write_msi_msg(struct irq_data *data,
 					  struct msi_msg *msg)