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xsk: add missing smp_rmb() in xsk_mmap

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[ Upstream commit e6762c8bcf ]

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: 37b076933a ("xsk: add missing write- and data-dependency barrier")
Fixes: c0c77d8fb7 ("xsk: add user memory registration support sockopt")
Signed-off-by: Magnus Karlsson <magnus.karlsson@intel.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Magnus Karlsson 2019-02-08 14:13:50 +01:00 committed by Greg Kroah-Hartman
parent 7bfcb0230e
commit 9aea648830
1 changed files with 4 additions and 0 deletions
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4
net/xdp/xsk.c
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@ -661,6 +661,8 @@ 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)
@ -670,6 +672,8 @@ 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;