lkml.org 
[lkml]   [2018]   [Jul]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 4.14 37/44] net/mlx4_en: Dont reuse RX page when XDP is set
Date
4.14-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Saeed Mahameed <saeedm@mellanox.com>

[ Upstream commit 432e629e56432064761be63bcd5e263c0920430d ]

When a new rx packet arrives, the rx path will decide whether to reuse
the remainder of the page or not according to one of the below conditions:
1. frag_info->frag_stride == PAGE_SIZE / 2
2. frags->page_offset + frag_info->frag_size > PAGE_SIZE;

The first condition is no met for when XDP is set.
For XDP, page_offset is always set to priv->rx_headroom which is
XDP_PACKET_HEADROOM and frag_info->frag_size is around mtu size + some
padding, still the 2nd release condition will hold since
XDP_PACKET_HEADROOM + 1536 < PAGE_SIZE, as a result the page will not
be released and will be _wrongly_ reused for next free rx descriptor.

In XDP there is an assumption to have a page per packet and reuse can
break such assumption and might cause packet data corruptions.

Fix this by adding an extra condition (!priv->rx_headroom) to the 2nd
case to avoid page reuse when XDP is set, since rx_headroom is set to 0
for non XDP setup and set to XDP_PACKET_HEADROOM for XDP setup.

No additional cache line is required for the new condition.

Fixes: 34db548bfb95 ("mlx4: add page recycling in receive path")
Signed-off-by: Saeed Mahameed <saeedm@mellanox.com>
Signed-off-by: Tariq Toukan <tariqt@mellanox.com>
Suggested-by: Martin KaFai Lau <kafai@fb.com>
CC: 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 | 8 ++++++--
1 file changed, 6 insertions(+), 2 deletions(-)

--- a/drivers/net/ethernet/mellanox/mlx4/en_rx.c
+++ b/drivers/net/ethernet/mellanox/mlx4/en_rx.c
@@ -472,10 +472,10 @@ static int mlx4_en_complete_rx_desc(stru
{
const struct mlx4_en_frag_info *frag_info = priv->frag_info;
unsigned int truesize = 0;
+ bool release = true;
int nr, frag_size;
struct page *page;
dma_addr_t dma;
- bool release;

/* Collect used fragments while replacing them in the HW descriptors */
for (nr = 0;; frags++) {
@@ -498,7 +498,11 @@ static int mlx4_en_complete_rx_desc(stru
release = page_count(page) != 1 ||
page_is_pfmemalloc(page) ||
page_to_nid(page) != numa_mem_id();
- } else {
+ } else if (!priv->rx_headroom) {
+ /* rx_headroom for non XDP setup is always 0.
+ * When XDP is set, the above condition will
+ * guarantee page is always released.
+ */
u32 sz_align = ALIGN(frag_size, SMP_CACHE_BYTES);

frags->page_offset += sz_align;

\
 
 \ /
  Last update: 2018-07-23 14:59    [W:0.181 / U:2.028 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site