Re: [PATCH V2 3/6] vDPA: implement IRQ offloading helpers in vDPA core

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On 2020/7/16 下午7:23, Zhu Lingshan wrote:
This commit implements IRQ offloading helpers


Let's say "vq irq allocate/free helpers" here.


in vDPA core by
introducing two couple of functions:

vdpa_alloc_vq_irq() and vdpa_free_vq_irq(): request irq and free
irq, will setup irq offloading.

vdpa_setup_irq() and vdpa_unsetup_irq(): supportive functions,
will call vhost_vdpa helpers.

Signed-off-by: Zhu Lingshan <lingshan.zhu@xxxxxxxxx>
Suggested-by: Jason Wang <jasowang@xxxxxxxxxx>
---
  drivers/vdpa/vdpa.c  | 42 ++++++++++++++++++++++++++++++++++++++++++
  include/linux/vdpa.h | 13 +++++++++++++
  2 files changed, 55 insertions(+)

diff --git a/drivers/vdpa/vdpa.c b/drivers/vdpa/vdpa.c
index ff6562f..cce4d91 100644
--- a/drivers/vdpa/vdpa.c
+++ b/drivers/vdpa/vdpa.c
@@ -163,6 +163,48 @@ void vdpa_unregister_driver(struct vdpa_driver *drv)
  }
  EXPORT_SYMBOL_GPL(vdpa_unregister_driver);
+static void vdpa_setup_irq(struct vdpa_device *vdev, int qid, int irq)
+{
+	struct vdpa_driver *drv = drv_to_vdpa(vdev->dev.driver);
+
+	if (drv->setup_vq_irq)
+		drv->setup_vq_irq(vdev, qid, irq);
+}
+
+static void vdpa_unsetup_irq(struct vdpa_device *vdev, int qid)
+{
+	struct vdpa_driver *drv = drv_to_vdpa(vdev->dev.driver);
+
+	if (drv->unsetup_vq_irq)
+		drv->unsetup_vq_irq(vdev, qid);


Do you need to check the existence of drv before calling unset_vq_irq()?

And how can this synchronize with driver releasing and binding?


+}
+
+int vdpa_alloc_vq_irq(struct device *dev, struct vdpa_device *vdev,
+		      unsigned int irq, irq_handler_t handler,
+		      unsigned long irqflags, const char *devname, void *dev_id,
+		      int qid)


Let's add comment as what has been done by other exported helpers.


+{
+	int ret;
+
+	ret = devm_request_irq(dev, irq, handler, irqflags, devname, dev_id);
+	if (ret)
+		dev_err(dev, "Failed to request irq for vq %d\n", qid);
+	else
+		vdpa_setup_irq(vdev, qid, irq);
+
+	return ret;
+
+}
+EXPORT_SYMBOL_GPL(vdpa_alloc_vq_irq);
+
+void vdpa_free_vq_irq(struct device *dev, struct vdpa_device *vdev, int irq,
+			 int qid, void *dev_id)
+{
+	devm_free_irq(dev, irq, dev_id);
+	vdpa_unsetup_irq(vdev, qid);
+}
+EXPORT_SYMBOL_GPL(vdpa_free_vq_irq);
+
  static int vdpa_init(void)
  {
  	return bus_register(&vdpa_bus);
diff --git a/include/linux/vdpa.h b/include/linux/vdpa.h
index 239db79..7d64d83 100644
--- a/include/linux/vdpa.h
+++ b/include/linux/vdpa.h
@@ -220,17 +220,30 @@ struct vdpa_device *__vdpa_alloc_device(struct device *parent,
int vdpa_register_device(struct vdpa_device *vdev);
  void vdpa_unregister_device(struct vdpa_device *vdev);
+/* request irq for a vq, setup irq offloading if its a vhost_vdpa vq */


Let's do the documentation in vdpa.c, and again, document the devres implications or j_xxxust name it as vdpa_devm_xxx.


+int vdpa_alloc_vq_irq(struct device *dev, struct vdpa_device *vdev,
+		      unsigned int irq, irq_handler_t handler,
+		      unsigned long irqflags, const char *devname, void *dev_id,
+		      int qid);
+/* free irq for a vq, unsetup irq offloading if its a vhost_vdpa vq */
+void vdpa_free_vq_irq(struct device *dev, struct vdpa_device *vdev, int irq,
+		      int qid, void *dev_id);
+
/**
   * vdpa_driver - operations for a vDPA driver
   * @driver: underlying device driver
   * @probe: the function to call when a device is found.  Returns 0 or -errno.
   * @remove: the function to call when a device is removed.
+ * @setup_vq_irq: setup irq offloading for a vhost_vdpa vq.
+ * @unsetup_vq_irq: unsetup offloading for a vhost_vdpa vq.


Let's not limit the methods for a specific use case like irq offloading here.


   */
  struct vdpa_driver {
  	struct device_driver driver;
  	int (*probe)(struct vdpa_device *vdev);
  	void (*remove)(struct vdpa_device *vdev);
+	void (*setup_vq_irq)(struct vdpa_device *vdev, int qid, int irq);
+	void (*unsetup_vq_irq)(struct vdpa_device *vdev, int qid);


To be consistent with the exported helper, let's use alloc_vq_irq/free_vq_irq

Thanks


  };
#define vdpa_register_driver(drv) \

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