| Message ID | 1549631630-29208-1-git-send-email-magnus.karlsson@intel.com |
|---|---|
| State | Accepted |
| Delegated to: | BPF Maintainers |
| Headers | show |
| Series | [bpf] xsk: add missing smp_rmb() in xsk_mmap | expand |
On Fri, Feb 08, 2019 at 02:13:50PM +0100, Magnus Karlsson wrote: > 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 <magnus.karlsson@intel.com> Applied, Thanks
diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c index a032684..45f3b52 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;
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 <magnus.karlsson@intel.com> --- net/xdp/xsk.c | 4 ++++ 1 file changed, 4 insertions(+)