Re: [PATCH 2/2] net: netcp: Allocate RX packet buffers using __GFP_DMA

From: Eric Dumazet
Date: Wed Jul 29 2015 - 17:00:11 EST


On Wed, 2015-07-29 at 11:10 -0400, WingMan Kwok wrote:
> The Keystone II DMA hardware can only access addresses in the
> lower 2 GiB of SDRAM. This patch makes sure the RX buffers are
> allocated using the __GFP_DMA flag so they meet this requirement.
>
> Signed-off-by: WingMan Kwok <w-kwok2@xxxxxx>
> Signed-off-by: Reece R. Pollack <x0183204@xxxxxx>
> ---
> drivers/net/ethernet/ti/netcp_core.c | 11 +++++++----
> 1 file changed, 7 insertions(+), 4 deletions(-)

Following patch gets rid of netdev_alloc_frag() which is not GFP_DMA
ready (and wont be)

diff --git a/drivers/net/ethernet/ti/netcp_core.c b/drivers/net/ethernet/ti/netcp_core.c
index 3ca87f26582a..0971c46d6cd5 100644
--- a/drivers/net/ethernet/ti/netcp_core.c
+++ b/drivers/net/ethernet/ti/netcp_core.c
@@ -808,14 +808,8 @@ static void netcp_allocate_rx_buf(struct netcp_intf *netcp, int fdq)
primary_buf_len = SKB_DATA_ALIGN(buf_len) +
SKB_DATA_ALIGN(sizeof(struct skb_shared_info));

- if (primary_buf_len <= PAGE_SIZE) {
- bufptr = netdev_alloc_frag(primary_buf_len);
- pad[1] = primary_buf_len;
- } else {
- bufptr = kmalloc(primary_buf_len, GFP_ATOMIC |
- GFP_DMA32 | __GFP_COLD);
- pad[1] = 0;
- }
+ bufptr = kmalloc(primary_buf_len, GFP_ATOMIC | GFP_DMA);
+ pad[1] = 0;

if (unlikely(!bufptr)) {
dev_warn_ratelimited(netcp->ndev_dev, "Primary RX buffer alloc failed\n");
@@ -827,7 +821,7 @@ static void netcp_allocate_rx_buf(struct netcp_intf *netcp, int fdq)

} else {
/* Allocate a secondary receive queue entry */
- page = alloc_page(GFP_ATOMIC | GFP_DMA32 | __GFP_COLD);
+ page = alloc_page(GFP_ATOMIC | GFP_DMA | __GFP_COLD);
if (unlikely(!page)) {
dev_warn_ratelimited(netcp->ndev_dev, "Secondary page alloc failed\n");
goto fail;


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