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Revert "vsock/virtio: fix skb overhead overflow on 32-bit builds"

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This reverts commit 4157501b9a ("vsock/virtio: fix skb overhead
overflow on 32-bit builds"). The fix was semantically correct (although
it would have been better to use mul_u32_u32(), as David pointed out),
but in practice we are estimating the memory used to allocate the SKBs,
and this will never cause a 32-bit variable to overflow on a 32-bit
system, since the memory would have run out long before that. On 64-bit,
SKB_TRUESIZE() already evaluates to size_t, so the multiplication is
already in 64-bit arithmetic without the cast.

Let's revert this to avoid unnecessary 64-bit multiplies on the
per-packet receive path on 32-bit systems.

Reported-by: David Laight <david.laight.linux@gmail.com>
Closes: https://lore.kernel.org/netdev/20260523173557.5cc4f4f6@pumpkin
Suggested-by: "Michael S. Tsirkin" <mst@redhat.com>
Signed-off-by: Stefano Garzarella <sgarzare@redhat.com>
Acked-by: Michael S. Tsirkin <mst@redhat.com>
Reviewed-by: David Laight <david.laight.linux@gmail.com>
Link: https://patch.msgid.link/20260527171046.130211-1-sgarzare@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Stefano Garzarella 2026-05-27 19:10:46 +02:00 committed by Jakub Kicinski
parent 1f03da8aea
commit e03f0b53b4
1 changed files with 1 additions and 1 deletions
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2
net/vmw_vsock/virtio_transport_common.c
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@ -417,7 +417,7 @@ static int virtio_transport_send_pkt_info(struct vsock_sock *vsk,
static bool virtio_transport_inc_rx_pkt(struct virtio_vsock_sock *vvs,
u32 len)
{
u64 skb_overhead = ((u64)skb_queue_len(&vvs->rx_queue) + 1) * SKB_TRUESIZE(0);
u64 skb_overhead = (skb_queue_len(&vvs->rx_queue) + 1) * SKB_TRUESIZE(0);
/* Allow at most buf_alloc * 2 total budget (payload + overhead),
* similar to how SO_RCVBUF is doubled to reserve space for sk_buff