From mboxrd@z Thu Jan 1 00:00:00 1970 From: Murali Karicheri Subject: Re: [PATCH 2/2] net: netcp: Allocate RX packet buffers using __GFP_DMA Date: Wed, 29 Jul 2015 17:22:55 -0400 Message-ID: <55B9442F.6040501@ti.com> References: <1438182653-2136-1-git-send-email-w-kwok2@ti.com> <1438182653-2136-2-git-send-email-w-kwok2@ti.com> <1438203596.20182.103.camel@edumazet-glaptop2.roam.corp.google.com> Mime-Version: 1.0 Content-Type: text/plain; charset="utf-8"; format=flowed Content-Transfer-Encoding: 7bit Cc: , , To: Eric Dumazet , WingMan Kwok Return-path: In-Reply-To: <1438203596.20182.103.camel@edumazet-glaptop2.roam.corp.google.com> Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On 07/29/2015 04:59 PM, Eric Dumazet wrote: > 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 >> Signed-off-by: Reece R. Pollack >> --- >> 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) > Eric, Thanks for the suggestion. I think the original assumption was that kmalloc() always allocate a minimum of 1 page for regular or small sized packets. The usage of netdev_alloc_frag() is to allocate small sized buffers. However kmalloc() can return different size buffers (/proc/slabinfo) and your below code should work fine for our driver. We will rework the patch as per your suggestion. Murali > 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; > > > > -- Murali Karicheri Linux Kernel, Keystone