virtio: unify config_changed handling

Replace duplicated code in all transports with a single wrapper in
virtio.c.

The only functional change is in virtio_mmio.c: if a buggy device sends
us an interrupt before driver is set, we previously returned IRQ_NONE,
now we return IRQ_HANDLED.

As this must not happen in practice, this does not look like a big deal.

See also commit 3fff0179e33cd7d0a688dab65700c46ad089e934
	virtio-pci: do not oops on config change if driver not loaded.
for the original motivation behind the driver check.

Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

7 files changed, 17 insertions, 28 deletions

diff --git a/drivers/misc/mic/card/mic_virtio.c b/drivers/misc/mic/card/mic_virtio.c
index f14b60080c21..e64794730e21 100644
--- a/drivers/misc/mic/card/mic_virtio.c
+++ b/drivers/misc/mic/card/mic_virtio.c
@@ -462,16 +462,12 @@ static void mic_handle_config_change(struct mic_device_desc __iomem *d,
         struct mic_device_ctrl __iomem *dc
                 = (void __iomem *)d + mic_aligned_desc_size(d);
         struct mic_vdev *mvdev = (struct mic_vdev *)ioread64(&dc->vdev);
-        struct virtio_driver *drv;
 
         if (ioread8(&dc->config_change) != MIC_VIRTIO_PARAM_CONFIG_CHANGED)
                 return;
 
         dev_dbg(mdrv->dev, "%s %d\n", __func__, __LINE__);
-        drv = container_of(mvdev->vdev.dev.driver,
-                                struct virtio_driver, driver);
-        if (drv->config_changed)
-                drv->config_changed(&mvdev->vdev);
+        virtio_config_changed(&mvdev->vdev);
         iowrite8(1, &dc->guest_ack);
 }
 
diff --git a/drivers/s390/kvm/kvm_virtio.c b/drivers/s390/kvm/kvm_virtio.c
index a1349653c6d9..643129070c51 100644
--- a/drivers/s390/kvm/kvm_virtio.c
+++ b/drivers/s390/kvm/kvm_virtio.c
@@ -406,15 +406,8 @@ static void kvm_extint_handler(struct ext_code ext_code,
 
         switch (param) {
         case VIRTIO_PARAM_CONFIG_CHANGED:
-        {
-                struct virtio_driver *drv;
-                drv = container_of(vq->vdev->dev.driver,
-                                   struct virtio_driver, driver);
-                if (drv->config_changed)
-                        drv->config_changed(vq->vdev);
-
+                virtio_config_changed(vq->vdev);
                 break;
-        }
         case VIRTIO_PARAM_DEV_ADD:
                 schedule_work(&hotplug_work);
                 break;
diff --git a/drivers/s390/kvm/virtio_ccw.c b/drivers/s390/kvm/virtio_ccw.c
index d2c0b442bce5..6cbe6ef3c889 100644
--- a/drivers/s390/kvm/virtio_ccw.c
+++ b/drivers/s390/kvm/virtio_ccw.c
@@ -940,11 +940,7 @@ static void virtio_ccw_int_handler(struct ccw_device *cdev,
                 vring_interrupt(0, vq);
         }
         if (test_bit(0, &vcdev->indicators2)) {
-                drv = container_of(vcdev->vdev.dev.driver,
-                                   struct virtio_driver, driver);
-
-                if (drv && drv->config_changed)
-                        drv->config_changed(&vcdev->vdev);
+                virtio_config_changed(&vcdev->vdev);
                 clear_bit(0, &vcdev->indicators2);
         }
 }
diff --git a/drivers/virtio/virtio.c b/drivers/virtio/virtio.c
index fed0ce198ae3..3980687401f6 100644
--- a/drivers/virtio/virtio.c
+++ b/drivers/virtio/virtio.c
@@ -239,6 +239,15 @@ void unregister_virtio_device(struct virtio_device *dev)
 }
 EXPORT_SYMBOL_GPL(unregister_virtio_device);
 
+void virtio_config_changed(struct virtio_device *dev)
+{
+        struct virtio_driver *drv = drv_to_virtio(dev->dev.driver);
+
+        if (drv && drv->config_changed)
+                drv->config_changed(dev);
+}
+EXPORT_SYMBOL_GPL(virtio_config_changed);
+
 static int virtio_init(void)
 {
         if (bus_register(&virtio_bus) != 0)
diff --git a/drivers/virtio/virtio_mmio.c b/drivers/virtio/virtio_mmio.c
index c600ccfd6922..ef9a1650bb80 100644
--- a/drivers/virtio/virtio_mmio.c
+++ b/drivers/virtio/virtio_mmio.c
@@ -234,8 +234,6 @@ static irqreturn_t vm_interrupt(int irq, void *opaque)
 {
         struct virtio_mmio_device *vm_dev = opaque;
         struct virtio_mmio_vq_info *info;
-        struct virtio_driver *vdrv = container_of(vm_dev->vdev.dev.driver,
-                        struct virtio_driver, driver);
         unsigned long status;
         unsigned long flags;
         irqreturn_t ret = IRQ_NONE;
@@ -244,9 +242,8 @@ static irqreturn_t vm_interrupt(int irq, void *opaque)
         status = readl(vm_dev->base + VIRTIO_MMIO_INTERRUPT_STATUS);
         writel(status, vm_dev->base + VIRTIO_MMIO_INTERRUPT_ACK);
 
-        if (unlikely(status & VIRTIO_MMIO_INT_CONFIG)
-                        && vdrv && vdrv->config_changed) {
-                vdrv->config_changed(&vm_dev->vdev);
+        if (unlikely(status & VIRTIO_MMIO_INT_CONFIG)) {
+                virtio_config_changed(&vm_dev->vdev);
                 ret = IRQ_HANDLED;
         }
 
diff --git a/drivers/virtio/virtio_pci.c b/drivers/virtio/virtio_pci.c
index add40d00dcdb..f39f4e772e6a 100644
--- a/drivers/virtio/virtio_pci.c
+++ b/drivers/virtio/virtio_pci.c
@@ -211,12 +211,8 @@ static bool vp_notify(struct virtqueue *vq)
 static irqreturn_t vp_config_changed(int irq, void *opaque)
 {
         struct virtio_pci_device *vp_dev = opaque;
-        struct virtio_driver *drv;
-        drv = container_of(vp_dev->vdev.dev.driver,
-                           struct virtio_driver, driver);
 
-        if (drv && drv->config_changed)
-                drv->config_changed(&vp_dev->vdev);
+        virtio_config_changed(&vp_dev->vdev);
         return IRQ_HANDLED;
 }
 
diff --git a/include/linux/virtio.h b/include/linux/virtio.h
index b46671e28de2..3c19bd3189cb 100644
--- a/include/linux/virtio.h
+++ b/include/linux/virtio.h
@@ -108,6 +108,8 @@ void unregister_virtio_device(struct virtio_device *dev);
 
 void virtio_break_device(struct virtio_device *dev);
 
+void virtio_config_changed(struct virtio_device *dev);
+
 /**
  * virtio_driver - operations for a virtio I/O driver
  * @driver: underlying device driver (populate name and owner).