From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jason Wang Subject: Re: [PATCH net-next 02/11] tuntap: switch to use XDP_PACKET_HEADROOM Date: Fri, 7 Sep 2018 11:12:24 +0800 Message-ID: <27def3eb-1b43-ec29-7380-c8078fe7ea8f@redhat.com> References: <20180906040526.22518-1-jasowang@redhat.com> <20180906040526.22518-3-jasowang@redhat.com> <20180906125718-mutt-send-email-mst@kernel.org> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Cc: netdev@vger.kernel.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org, virtualization@lists.linux-foundation.org To: "Michael S. Tsirkin" Return-path: In-Reply-To: <20180906125718-mutt-send-email-mst@kernel.org> Content-Language: en-US Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org On 2018年09月07日 00:57, Michael S. Tsirkin wrote: > On Thu, Sep 06, 2018 at 12:05:17PM +0800, Jason Wang wrote: >> Signed-off-by: Jason Wang > Acked-by: Michael S. Tsirkin > > any idea why didn't we do this straight away? Dunno, but git grep told me not all XDP capable driver use this (e.g virtio_net has its own value). Anyway, I think it's ok for driver to have their specific value if they can make sure the value is equal or greater than XDP_PACKET_HEADROOM. Thanks > >> --- >> drivers/net/tun.c | 3 +-- >> 1 file changed, 1 insertion(+), 2 deletions(-) >> >> diff --git a/drivers/net/tun.c b/drivers/net/tun.c >> index 2c548bd20393..d3677a544b56 100644 >> --- a/drivers/net/tun.c >> +++ b/drivers/net/tun.c >> @@ -113,7 +113,6 @@ do { \ >> } while (0) >> #endif >> >> -#define TUN_HEADROOM 256 >> #define TUN_RX_PAD (NET_IP_ALIGN + NET_SKB_PAD) >> >> /* TUN device flags */ >> @@ -1654,7 +1653,7 @@ static struct sk_buff *tun_build_skb(struct tun_struct *tun, >> rcu_read_lock(); >> xdp_prog = rcu_dereference(tun->xdp_prog); >> if (xdp_prog) >> - pad += TUN_HEADROOM; >> + pad += XDP_PACKET_HEADROOM; >> buflen += SKB_DATA_ALIGN(len + pad); >> rcu_read_unlock(); >> >> -- >> 2.17.1