xsk: add missing write- and data-dependency barrier
Here, we add a missing write-barrier, and use READ_ONCE for the
data-dependency barrier.
Signed-off-by: Björn Töpel <bjorn.topel@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c
index 378dd92..01f010e 100644
--- a/net/xdp/xsk.c
+++ b/net/xdp/xsk.c
@@ -228,6 +228,8 @@ static int xsk_init_queue(u32 entries, struct xsk_queue **queue,
if (!q)
return -ENOMEM;
+ /* Make sure queue is ready before it can be seen by others */
+ smp_wmb();
*queue = q;
return 0;
}
@@ -532,21 +534,23 @@ static int xsk_mmap(struct file *file, struct socket *sock,
unsigned long size = vma->vm_end - vma->vm_start;
struct xdp_sock *xs = xdp_sk(sock->sk);
struct xsk_queue *q = NULL;
+ struct xdp_umem *umem;
unsigned long pfn;
struct page *qpg;
if (offset == XDP_PGOFF_RX_RING) {
- q = xs->rx;
+ q = READ_ONCE(xs->rx);
} else if (offset == XDP_PGOFF_TX_RING) {
- q = xs->tx;
+ q = READ_ONCE(xs->tx);
} else {
- if (!xs->umem)
+ umem = READ_ONCE(xs->umem);
+ if (!umem)
return -EINVAL;
if (offset == XDP_UMEM_PGOFF_FILL_RING)
- q = xs->umem->fq;
+ q = READ_ONCE(umem->fq);
else if (offset == XDP_UMEM_PGOFF_COMPLETION_RING)
- q = xs->umem->cq;
+ q = READ_ONCE(umem->cq);
}
if (!q)