On Sun, Mar 05, 2023 at 11:06:26PM +0300, Arseniy Krasnov wrote:
Substraction of 'skb->len' is redundant here: 'skb_headroom()' is delta
between 'data' and 'head' pointers, e.g. it is number of bytes returned
to user (of course accounting size of header). 'skb->len' is number of
bytes rest in buffer.
Fixes: 71dc9ec9ac7d ("virtio/vsock: replace virtio_vsock_pkt with sk_buff")
Signed-off-by: Arseniy Krasnov <AVKrasnov@xxxxxxxxxxxxxx>
---
net/vmw_vsock/virtio_transport_common.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/net/vmw_vsock/virtio_transport_common.c b/net/vmw_vsock/virtio_transport_common.c
index a1581c77cf84..2e2a773df5c1 100644
--- a/net/vmw_vsock/virtio_transport_common.c
+++ b/net/vmw_vsock/virtio_transport_common.c
@@ -255,7 +255,7 @@ static void virtio_transport_dec_rx_pkt(struct virtio_vsock_sock *vvs,
{
int len;
- len = skb_headroom(skb) - sizeof(struct virtio_vsock_hdr) - skb->len;
+ len = skb_headroom(skb) - sizeof(struct virtio_vsock_hdr);
IIUC virtio_transport_dec_rx_pkt() is always called after skb_pull(),
so skb_headroom() is returning the amount of space we removed.
Looking at the other patches in this series, I think maybe we should
change virtio_transport_dec_rx_pkt() and virtio_transport_inc_rx_pkt()
by passing the value to subtract or add directly.
Since some times we don't remove the whole payload, so it would be
better to call it with the value in hdr->len.
I mean something like this (untested):
index a1581c77cf84..9e69ae7a9a96 100644
--- a/net/vmw_vsock/virtio_transport_common.c
+++ b/net/vmw_vsock/virtio_transport_common.c
@@ -241,21 +241,18 @@ static int virtio_transport_send_pkt_info(struct vsock_sock *vsk,
}
static bool virtio_transport_inc_rx_pkt(struct virtio_vsock_sock *vvs,
- struct sk_buff *skb)
+ u32 len)
{
- if (vvs->rx_bytes + skb->len > vvs->buf_alloc)
+ if (vvs->rx_bytes + len > vvs->buf_alloc)
return false;
- vvs->rx_bytes += skb->len;
+ vvs->rx_bytes += len;
return true;
}
static void virtio_transport_dec_rx_pkt(struct virtio_vsock_sock *vvs,
- struct sk_buff *skb)
+ u32 len)
{
- int len;
-
- len = skb_headroom(skb) - sizeof(struct virtio_vsock_hdr) - skb->len;
vvs->rx_bytes -= len;
vvs->fwd_cnt += len;
}
@@ -388,7 +385,7 @@ virtio_transport_stream_do_dequeue(struct vsock_sock *vsk,
skb_pull(skb, bytes);
if (skb->len == 0) {
- virtio_transport_dec_rx_pkt(vvs, skb);
+ virtio_transport_dec_rx_pkt(vvs, bytes);
consume_skb(skb);
} else {
__skb_queue_head(&vvs->rx_queue, skb);
@@ -437,17 +434,17 @@ static int virtio_transport_seqpacket_do_dequeue(struct vsock_sock *vsk,
while (!msg_ready) {
struct virtio_vsock_hdr *hdr;
+ size_t pkt_len;
skb = __skb_dequeue(&vvs->rx_queue);
if (!skb)
break;
hdr = virtio_vsock_hdr(skb);
+ pkt_len = (size_t)le32_to_cpu(hdr->len);
if (dequeued_len >= 0) {
- size_t pkt_len;
size_t bytes_to_copy;
- pkt_len = (size_t)le32_to_cpu(hdr->len);
bytes_to_copy = min(user_buf_len, pkt_len);
if (bytes_to_copy) {
@@ -484,7 +481,7 @@ static int virtio_transport_seqpacket_do_dequeue(struct vsock_sock *vsk,
msg->msg_flags |= MSG_EOR;
}
- virtio_transport_dec_rx_pkt(vvs, skb);
+ virtio_transport_dec_rx_pkt(vvs, pkt_len);
kfree_skb(skb);
}
@@ -1040,7 +1037,7 @@ virtio_transport_recv_enqueue(struct vsock_sock *vsk,
spin_lock_bh(&vvs->rx_lock);
- can_enqueue = virtio_transport_inc_rx_pkt(vvs, skb);
+ can_enqueue = virtio_transport_inc_rx_pkt(vvs, len);
if (!can_enqueue) {
free_pkt = true;
goto out;
When we used vsock_pkt, we were passing the structure because the `len`
field was immutable (and copied from the header), whereas with skb it
can change and so we introduced these errors.
What do you think?
Thanks,
Stefano
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