[Devel] [PATCH RHEL9 COMMIT] vhost/vsock: split out vhost_vsock_drop_backends helper

[Konstantin Khorenko]

The commit is pushed to "branch-rh9-5.14.0-427.44.1.vz9.80.x-ovz" and will appear at git at bitbucket.org:openvz/vzkernel.git
after rh9-5.14.0-427.44.1.vz9.80.8
------>
commit 31d603dfc116ddaadf4167eb823a333ba805163f
Author: Pavel Tikhomirov <ptikhomirov at virtuozzo.com>
Date:   Tue Jan 28 18:48:00 2025 +0800

    vhost/vsock: split out vhost_vsock_drop_backends helper
    
    Split the actual backend dropping part from vhost_vsock_stop, we will
    need to use it where vsock->dev.mutex is already taken and owner is
    checked.
    
    https://virtuozzo.atlassian.net/browse/VSTOR-98105
    Signed-off-by: Pavel Tikhomirov <ptikhomirov at virtuozzo.com>
    
    Feature: vhost-vsock: VHOST_RESET_OWNER ioctl
---
 drivers/vhost/vsock.c | 26 +++++++++++++++++---------
 1 file changed, 17 insertions(+), 9 deletions(-)

diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
index f2532b954e33..ca6a95204b4a 100644
--- a/drivers/vhost/vsock.c
+++ b/drivers/vhost/vsock.c
@@ -615,9 +615,24 @@ static int vhost_vsock_start(struct vhost_vsock *vsock)
 	return ret;
 }
 
-static int vhost_vsock_stop(struct vhost_vsock *vsock, bool check_owner)
+static void vhost_vsock_drop_backends(struct vhost_vsock *vsock)
 {
+	struct vhost_virtqueue *vq;
 	size_t i;
+
+	lockdep_assert_held(&vsock->dev.mutex);
+
+	for (i = 0; i < ARRAY_SIZE(vsock->vqs); i++) {
+		vq = &vsock->vqs[i];
+
+		mutex_lock(&vq->mutex);
+		vhost_vq_set_backend(vq, NULL);
+		mutex_unlock(&vq->mutex);
+	}
+}
+
+static int vhost_vsock_stop(struct vhost_vsock *vsock, bool check_owner)
+{
 	int ret = 0;
 
 	mutex_lock(&vsock->dev.mutex);
@@ -628,14 +643,7 @@ static int vhost_vsock_stop(struct vhost_vsock *vsock, bool check_owner)
 			goto err;
 	}
 
-	for (i = 0; i < ARRAY_SIZE(vsock->vqs); i++) {
-		struct vhost_virtqueue *vq = &vsock->vqs[i];
-
-		mutex_lock(&vq->mutex);
-		vhost_vq_set_backend(vq, NULL);
-		mutex_unlock(&vq->mutex);
-	}
-
+	vhost_vsock_drop_backends(vsock);
 err:
 	mutex_unlock(&vsock->dev.mutex);
 	return ret;