[PATCH 3.11 20/66] net/mlx4_en: Fix pages never dma unmapped on rx

Greg Kroah-Hartman
2013-11-01T22:24:39Z

From: Amir Vadai <amirv@mellanox.com>

[ Upstream commit 021f1107ffdae7a82af6c53f4c52654062e365c6 ]

This patch fixes a bug introduced by commit 51151a16 (mlx4: allow
order-0 memory allocations in RX path).

dma_unmap_page never reached because condition to detect last fragment
in page is wrong. offset+frag_stride can't be greater than size, need to
make sure no additional frag will fit in page => compare offset +
frag_stride + next_frag_size instead.
next_frag_size is the same as the current one, since page is shared only
with frags of the same size.

CC: Eric Dumazet <edumazet@google.com>
Signed-off-by: Amir Vadai <amirv@mellanox.com>
Acked-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
drivers/net/ethernet/mellanox/mlx4/en_rx.c | 5 +++--
1 file changed, 3 insertions(+), 2 deletions(-)

--- a/drivers/net/ethernet/mellanox/mlx4/en_rx.c
+++ b/drivers/net/ethernet/mellanox/mlx4/en_rx.c
@@ -135,9 +135,10 @@ static void mlx4_en_free_frag(struct mlx
int i)
{
const struct mlx4_en_frag_info *frag_info = &priv->frag_info[i];
+ u32 next_frag_end = frags[i].page_offset + 2 * frag_info->frag_stride;

- if (frags[i].page_offset + frag_info->frag_stride >
- frags[i].page_size)
+
+ if (next_frag_end > frags[i].page_size)
dma_unmap_page(priv->ddev, frags[i].dma, frags[i].page_size,
PCI_DMA_FROMDEVICE);