virtio/vsock: rework MSG_PEEK for SOCK_STREAM

This reworks current implementation of MSG_PEEK logic:
1) Replaces 'skb_queue_walk_safe()' with 'skb_queue_walk()'. There is
   no need in the first one, as there are no removes of skb in loop.
2) Removes nested while loop - MSG_PEEK logic could be implemented
   without it: just iterate over skbs without removing it and copy
   data from each until destination buffer is not full.

Signed-off-by: Arseniy Krasnov <AVKrasnov@sberdevices.ru>
Reviewed-by: Bobby Eshleman <bobby.eshleman@bytedance.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Paolo Abeni <pabeni@redhat.com>

diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
index b769fc2589315098083f5b2a2c6850438d4265c4..2ee40574c3398cb080cc06f359032fd6d081c6dd 100644 (file)
--- a/net/vmw_vsock/virtio_transport_common.c
+++ b/net/vmw_vsock/virtio_transport_common.c
@@ -348,37 +348,34 @@ virtio_transport_stream_do_peek(struct vsock_sock *vsk,
                                size_t len)
 {
        struct virtio_vsock_sock *vvs = vsk->trans;
-       size_t bytes, total = 0, off;
-       struct sk_buff *skb, *tmp;
-       int err = -EFAULT;
+       struct sk_buff *skb;
+       size_t total = 0;
+       int err;
 
        spin_lock_bh(&vvs->rx_lock);
 
-       skb_queue_walk_safe(&vvs->rx_queue, skb,  tmp) {
-               off = 0;
+       skb_queue_walk(&vvs->rx_queue, skb) {
+               size_t bytes;
 
-               if (total == len)
-                       break;
+               bytes = len - total;
+               if (bytes > skb->len)
+                       bytes = skb->len;
 
-               while (total < len && off < skb->len) {
-                       bytes = len - total;
-                       if (bytes > skb->len - off)
-                               bytes = skb->len - off;
+               spin_unlock_bh(&vvs->rx_lock);
 
-                       /* sk_lock is held by caller so no one else can dequeue.
-                        * Unlock rx_lock since memcpy_to_msg() may sleep.
-                        */
-                       spin_unlock_bh(&vvs->rx_lock);
+               /* sk_lock is held by caller so no one else can dequeue.
+                * Unlock rx_lock since memcpy_to_msg() may sleep.
+                */
+               err = memcpy_to_msg(msg, skb->data, bytes);
+               if (err)
+                       goto out;
 
-                       err = memcpy_to_msg(msg, skb->data + off, bytes);
-                       if (err)
-                               goto out;
+               total += bytes;
 
-                       spin_lock_bh(&vvs->rx_lock);
+               spin_lock_bh(&vvs->rx_lock);
 
-                       total += bytes;
-                       off += bytes;
-               }
+               if (total == len)
+                       break;
        }
 
        spin_unlock_bh(&vvs->rx_lock);