[PATCH 4.9 37/51] vsock: lookup and setup guest_cid inside vhost_vsock_lock

Greg Kroah-Hartman
2018-12-11T16:13:05Z

[ Upstream commit 6c083c2b8a0a110cad936bc0a2c089f0d8115175 ]

Multi vsocks may setup the same cid at the same time.

Signed-off-by: Gao feng <omarapazanadi@gmail.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
drivers/vhost/vsock.c | 25 +++++++++++++++++--------
1 file changed, 17 insertions(+), 8 deletions(-)

diff --git a/drivers/vhost/vsock.c b/drivers/vhost/vsock.c
index 0ec970ca64ce..6bca57896915 100644
--- a/drivers/vhost/vsock.c
+++ b/drivers/vhost/vsock.c
@@ -50,11 +50,10 @@ static u32 vhost_transport_get_local_cid(void)
return VHOST_VSOCK_DEFAULT_HOST_CID;
}

-static struct vhost_vsock *vhost_vsock_get(u32 guest_cid)
+static struct vhost_vsock *__vhost_vsock_get(u32 guest_cid)
{
struct vhost_vsock *vsock;

- spin_lock_bh(&vhost_vsock_lock);
list_for_each_entry(vsock, &vhost_vsock_list, list) {
u32 other_cid = vsock->guest_cid;

@@ -63,15 +62,24 @@ static struct vhost_vsock *vhost_vsock_get(u32 guest_cid)
continue;

if (other_cid == guest_cid) {
- spin_unlock_bh(&vhost_vsock_lock);
return vsock;
}
}
- spin_unlock_bh(&vhost_vsock_lock);

return NULL;
}

+static struct vhost_vsock *vhost_vsock_get(u32 guest_cid)
+{
+ struct vhost_vsock *vsock;
+
+ spin_lock_bh(&vhost_vsock_lock);
+ vsock = __vhost_vsock_get(guest_cid);
+ spin_unlock_bh(&vhost_vsock_lock);
+
+ return vsock;
+}
+
static void
vhost_transport_do_send_pkt(struct vhost_vsock *vsock,
struct vhost_virtqueue *vq)
@@ -607,11 +615,12 @@ static int vhost_vsock_set_cid(struct vhost_vsock *vsock, u64 guest_cid)
return -EINVAL;

/* Refuse if CID is already in use */
- other = vhost_vsock_get(guest_cid);
- if (other && other != vsock)
- return -EADDRINUSE;
-
spin_lock_bh(&vhost_vsock_lock);
+ other = __vhost_vsock_get(guest_cid);
+ if (other && other != vsock) {
+ spin_unlock_bh(&vhost_vsock_lock);
+ return -EADDRINUSE;
+ }
vsock->guest_cid = guest_cid;
spin_unlock_bh(&vhost_vsock_lock);

--
2.19.1