2022-06-03 17:02:07

by Felix Fietkau

Subject: Re: [PATCH] net: ethernet: mtk_eth_soc: fix misuse of mem alloc interface netdev_alloc_frag

On 03.06.22 06:10, Chen Lin wrote:
> When rx_flag == MTK_RX_FLAGS_HWLRO,
> rx_data_len = MTK_MAX_LRO_RX_LENGTH(4096 * 3) > PAGE_SIZE.
> netdev_alloc_frag is for alloction of page fragment only.
> Reference to other drivers and Documentation/vm/page_frags.rst
>
> Branch to use kmalloc when rx_data_len > PAGE_SIZE.
>
> Signed-off-by: Chen Lin <[email protected]>
> ---
> drivers/net/ethernet/mediatek/mtk_eth_soc.c | 5 ++++-
> 1 file changed, 4 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/net/ethernet/mediatek/mtk_eth_soc.c b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
> index b3b3c07..d0eebca 100644
> --- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
> +++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
> @@ -1914,7 +1914,10 @@ static int mtk_rx_alloc(struct mtk_eth *eth, int ring_no, int rx_flag)
> return -ENOMEM;
>
> for (i = 0; i < rx_dma_size; i++) {
> - ring->data[i] = netdev_alloc_frag(ring->frag_size);
> + if (ring->frag_size <= PAGE_SIZE)
> + ring->data[i] = netdev_alloc_frag(ring->frag_size);
> + else
> + ring->data[i] = kmalloc(ring->frag_size, GFP_KERNEL);
I'm pretty sure you also need to update all the other places in the code
that currently assume that the buffer is allocated using the page frag
allocator.

- Felix

2022-06-06 05:20:40

by Chen Lin

Subject: [PATCH v2] net: ethernet: mtk_eth_soc: fix misuse of mem alloc interface netdev[napi]_alloc_frag

When rx_flag == MTK_RX_FLAGS_HWLRO,
rx_data_len = MTK_MAX_LRO_RX_LENGTH(4096 * 3) > PAGE_SIZE.
netdev_alloc_frag is for alloction of page fragment only.
Reference to other drivers and Documentation/vm/page_frags.rst

Branch to use alloc_pages when ring->frag_size > PAGE_SIZE.

Signed-off-by: Chen Lin <[email protected]>
---
drivers/net/ethernet/mediatek/mtk_eth_soc.c | 22 ++++++++++++++++++++--
1 file changed, 20 insertions(+), 2 deletions(-)

diff --git a/drivers/net/ethernet/mediatek/mtk_eth_soc.c b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
index b3b3c07..772d903 100644
--- a/drivers/net/ethernet/mediatek/mtk_eth_soc.c
+++ b/drivers/net/ethernet/mediatek/mtk_eth_soc.c
@@ -1467,7 +1467,16 @@ static int mtk_poll_rx(struct napi_struct *napi, int budget,
goto release_desc;

/* alloc new buffer */
- new_data = napi_alloc_frag(ring->frag_size);
+ if (ring->frag_size <= PAGE_SIZE) {
+ new_data = napi_alloc_frag(ring->frag_size);
+ } else {
+ struct page *page;
+ unsigned int order = get_order(ring->frag_size);
+
+ page = alloc_pages(GFP_ATOMIC | __GFP_COMP |
+ __GFP_NOWARN, order);
+ new_data = page ? page_address(page) : NULL;
+ }
if (unlikely(!new_data)) {
netdev->stats.rx_dropped++;
goto release_desc;
@@ -1914,7 +1923,16 @@ static int mtk_rx_alloc(struct mtk_eth *eth, int ring_no, int rx_flag)
return -ENOMEM;

for (i = 0; i < rx_dma_size; i++) {
- ring->data[i] = netdev_alloc_frag(ring->frag_size);
+ if (ring->frag_size <= PAGE_SIZE) {
+ ring->data[i] = netdev_alloc_frag(ring->frag_size);
+ } else {
+ struct page *page;
+ unsigned int order = get_order(ring->frag_size);
+
+ page = alloc_pages(GFP_KERNEL | __GFP_COMP |
+ __GFP_NOWARN, order);
+ ring->data[i] = page ? page_address(page) : NULL;
+ }
if (!ring->data[i])
return -ENOMEM;
}
--
1.7.9.5