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authorEric Dumazet <edumazet@google.com>2014-10-10 04:48:17 -0700
committerDavid S. Miller <davem@davemloft.net>2014-10-10 15:37:28 -0400
commit98226208c8a1fe5834e92d827a2a1e8051a17943 (patch)
tree09bc0b1ebf516dcba2d21b93d98dc0e3d2bc3181
parentec91698360b3818ff426488a1529811f7a7ab87f (diff)
mlx4: fix race accessing page->_count
This is illegal to use atomic_set(&page->_count, ...) even if we 'own' the page. Other entities in the kernel need to use get_page_unless_zero() to get a reference to the page before testing page properties, so we could loose a refcount increment. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--drivers/net/ethernet/mellanox/mlx4/en_rx.c6
1 files changed, 3 insertions, 3 deletions
diff --git a/drivers/net/ethernet/mellanox/mlx4/en_rx.c b/drivers/net/ethernet/mellanox/mlx4/en_rx.c
index a33048ee9621..01660c595f5c 100644
--- a/drivers/net/ethernet/mellanox/mlx4/en_rx.c
+++ b/drivers/net/ethernet/mellanox/mlx4/en_rx.c
@@ -76,10 +76,10 @@ static int mlx4_alloc_pages(struct mlx4_en_priv *priv,
page_alloc->dma = dma;
page_alloc->page_offset = frag_info->frag_align;
/* Not doing get_page() for each frag is a big win
- * on asymetric workloads.
+ * on asymetric workloads. Note we can not use atomic_set().
*/
- atomic_set(&page->_count,
- page_alloc->page_size / frag_info->frag_stride);
+ atomic_add(page_alloc->page_size / frag_info->frag_stride - 1,
+ &page->_count);
return 0;
}