[PATCH v10 07/10] vfio: Add helper to search vfio_device in a dev_set

[Yi Liu <yi.l.liu@xxxxxxxxx>]

There are drivers that need to search vfio_device within a given dev_set.
e.g. vfio-pci. So add a helper.

vfio_pci_is_device_in_set() now returns -EBUSY in commit a882c16a2b7e
("vfio/pci: Change vfio_pci_try_bus_reset() to use the dev_set") where
it was trying to preserve the return of vfio_pci_try_zap_and_vma_lock_cb().
However, it makes more sense to return -ENODEV.

Suggested-by: Alex Williamson <alex.williamson@xxxxxxxxxx>
Reviewed-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
Tested-by: Yanting Jiang <yanting.jiang@xxxxxxxxx>
Tested-by: Terrence Xu <terrence.xu@xxxxxxxxx>
Tested-by: Zhenzhong Duan <zhenzhong.duan@xxxxxxxxx>
Signed-off-by: Yi Liu <yi.l.liu@xxxxxxxxx>
---
 drivers/vfio/pci/vfio_pci_core.c |  6 +-----
 drivers/vfio/vfio_main.c         | 15 +++++++++++++++
 include/linux/vfio.h             |  3 +++
 3 files changed, 19 insertions(+), 5 deletions(-)

diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c
index 3d595ad2ed0a..5b5316a5484a 100644
--- a/drivers/vfio/pci/vfio_pci_core.c
+++ b/drivers/vfio/pci/vfio_pci_core.c
@@ -2377,12 +2377,8 @@ static bool vfio_dev_in_groups(struct vfio_pci_core_device *vdev,
 static int vfio_pci_is_device_in_set(struct pci_dev *pdev, void *data)
 {
 	struct vfio_device_set *dev_set = data;
-	struct vfio_device *cur;
 
-	list_for_each_entry(cur, &dev_set->device_list, dev_set_list)
-		if (cur->dev == &pdev->dev)
-			return 0;
-	return -EBUSY;
+	return vfio_find_device_in_devset(dev_set, &pdev->dev) ? 0 : -ENODEV;
 }
 
 /*
diff --git a/drivers/vfio/vfio_main.c b/drivers/vfio/vfio_main.c
index f0ca33b2e1df..ab4f3a794f78 100644
--- a/drivers/vfio/vfio_main.c
+++ b/drivers/vfio/vfio_main.c
@@ -141,6 +141,21 @@ unsigned int vfio_device_set_open_count(struct vfio_device_set *dev_set)
 }
 EXPORT_SYMBOL_GPL(vfio_device_set_open_count);
 
+struct vfio_device *
+vfio_find_device_in_devset(struct vfio_device_set *dev_set,
+			   struct device *dev)
+{
+	struct vfio_device *cur;
+
+	lockdep_assert_held(&dev_set->lock);
+
+	list_for_each_entry(cur, &dev_set->device_list, dev_set_list)
+		if (cur->dev == dev)
+			return cur;
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(vfio_find_device_in_devset);
+
 /*
  * Device objects - create, release, get, put, search
  */
diff --git a/include/linux/vfio.h b/include/linux/vfio.h
index 2a45853773a6..ee120d2d530b 100644
--- a/include/linux/vfio.h
+++ b/include/linux/vfio.h
@@ -244,6 +244,9 @@ void vfio_unregister_group_dev(struct vfio_device *device);
 
 int vfio_assign_device_set(struct vfio_device *device, void *set_id);
 unsigned int vfio_device_set_open_count(struct vfio_device_set *dev_set);
+struct vfio_device *
+vfio_find_device_in_devset(struct vfio_device_set *dev_set,
+			   struct device *dev);
 
 int vfio_mig_get_next_state(struct vfio_device *device,
 			    enum vfio_device_mig_state cur_fsm,
-- 
2.34.1