From e6762c8bcf982821935a2b1cb33cf8335d0eefae Mon Sep 17 00:00:00 2001 From: Magnus Karlsson Date: Fri, 8 Feb 2019 14:13:50 +0100 Subject: xsk: add missing smp_rmb() in xsk_mmap All the setup code in AF_XDP is protected by a mutex with the exception of the mmap code that cannot use it. To make sure that a process banging on the mmap call at the same time as another process is setting up the socket, smp_wmb() calls were added in the umem registration code and the queue creation code, so that the published structures that xsk_mmap needs would be consistent. However, the corresponding smp_rmb() calls were not added to the xsk_mmap code. This patch adds these calls. Fixes: 37b076933a8e3 ("xsk: add missing write- and data-dependency barrier") Fixes: c0c77d8fb787c ("xsk: add user memory registration support sockopt") Signed-off-by: Magnus Karlsson Signed-off-by: Alexei Starovoitov --- net/xdp/xsk.c | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'net/xdp/xsk.c') diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c index a03268454a27..45f3b528dc09 100644 --- a/net/xdp/xsk.c +++ b/net/xdp/xsk.c @@ -669,6 +669,8 @@ static int xsk_mmap(struct file *file, struct socket *sock, if (!umem) return -EINVAL; + /* Matches the smp_wmb() in XDP_UMEM_REG */ + smp_rmb(); if (offset == XDP_UMEM_PGOFF_FILL_RING) q = READ_ONCE(umem->fq); else if (offset == XDP_UMEM_PGOFF_COMPLETION_RING) @@ -678,6 +680,8 @@ static int xsk_mmap(struct file *file, struct socket *sock, if (!q) return -EINVAL; + /* Matches the smp_wmb() in xsk_init_queue */ + smp_rmb(); qpg = virt_to_head_page(q->ring); if (size > (PAGE_SIZE << compound_order(qpg))) return -EINVAL; -- cgit v1.2.3-59-g8ed1b