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Wed, 15 Apr 2026 01:27:19 -0700 (PDT) Received: from KERNELXING-MB0.tencent.com ([43.132.141.25]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-2b4782a93c7sm12174215ad.62.2026.04.15.01.27.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 15 Apr 2026 01:27:18 -0700 (PDT) From: Jason Xing To: davem@davemloft.net, edumazet@google.com, kuba@kernel.org, pabeni@redhat.com, bjorn@kernel.org, magnus.karlsson@intel.com, maciej.fijalkowski@intel.com, jonathan.lemon@gmail.com, sdf@fomichev.me, ast@kernel.org, daniel@iogearbox.net, hawk@kernel.org, john.fastabend@gmail.com Cc: bpf@vger.kernel.org, netdev@vger.kernel.org, Jason Xing Subject: [PATCH RFC net-next v4 02/14] xsk: extend xsk_build_skb() to support passing an already allocated skb Date: Wed, 15 Apr 2026 16:26:42 +0800 Message-Id: <20260415082654.21026-3-kerneljasonxing@gmail.com> X-Mailer: git-send-email 2.33.0 In-Reply-To: <20260415082654.21026-1-kerneljasonxing@gmail.com> References: <20260415082654.21026-1-kerneljasonxing@gmail.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit From: Jason Xing To avoid reinvent the wheel, the patch provides a way to let batch feature reuse xsk_build_skb() as the rest process of the whole initialization just after the skb is allocated. The original xsk_build_skb() itself allocates a new skb by calling sock_alloc_send_skb whether in copy mode or zerocopy mode. Add a new parameter allocated skb to let other callers to pass an already allocated skb to support later xmit batch feature. It replaces the previous allocation of memory function with a bulk one. Signed-off-by: Jason Xing --- include/net/xdp_sock.h | 3 +++ net/xdp/xsk.c | 23 ++++++++++++++++------- 2 files changed, 19 insertions(+), 7 deletions(-) diff --git a/include/net/xdp_sock.h b/include/net/xdp_sock.h index 965cab9a0465..90c709fd1239 100644 --- a/include/net/xdp_sock.h +++ b/include/net/xdp_sock.h @@ -133,6 +133,9 @@ int xsk_generic_rcv(struct xdp_sock *xs, struct xdp_buff *xdp); int __xsk_map_redirect(struct xdp_sock *xs, struct xdp_buff *xdp); void __xsk_map_flush(struct list_head *flush_list); INDIRECT_CALLABLE_DECLARE(void xsk_destruct_skb(struct sk_buff *)); +struct sk_buff *xsk_build_skb(struct xdp_sock *xs, + struct sk_buff *allocated_skb, + struct xdp_desc *desc); /** * xsk_tx_metadata_to_compl - Save enough relevant metadata information diff --git a/net/xdp/xsk.c b/net/xdp/xsk.c index 6122db8606fe..ecd5b9c424b8 100644 --- a/net/xdp/xsk.c +++ b/net/xdp/xsk.c @@ -718,6 +718,7 @@ static int xsk_skb_metadata(struct sk_buff *skb, void *buffer, } static struct sk_buff *xsk_build_skb_zerocopy(struct xdp_sock *xs, + struct sk_buff *allocated_skb, struct xdp_desc *desc) { struct xsk_buff_pool *pool = xs->pool; @@ -734,7 +735,10 @@ static struct sk_buff *xsk_build_skb_zerocopy(struct xdp_sock *xs, if (!skb) { hr = max(NET_SKB_PAD, L1_CACHE_ALIGN(xs->dev->needed_headroom)); - skb = sock_alloc_send_skb(&xs->sk, hr, 1, &err); + if (!allocated_skb) + skb = sock_alloc_send_skb(&xs->sk, hr, 1, &err); + else + skb = allocated_skb; if (unlikely(!skb)) return ERR_PTR(err); @@ -799,15 +803,16 @@ static struct sk_buff *xsk_build_skb_zerocopy(struct xdp_sock *xs, return skb; } -static struct sk_buff *xsk_build_skb(struct xdp_sock *xs, - struct xdp_desc *desc) +struct sk_buff *xsk_build_skb(struct xdp_sock *xs, + struct sk_buff *allocated_skb, + struct xdp_desc *desc) { struct net_device *dev = xs->dev; struct sk_buff *skb = xs->skb; int err; if (dev->priv_flags & IFF_TX_SKB_NO_LINEAR) { - skb = xsk_build_skb_zerocopy(xs, desc); + skb = xsk_build_skb_zerocopy(xs, allocated_skb, desc); if (IS_ERR(skb)) { err = PTR_ERR(skb); skb = NULL; @@ -822,8 +827,12 @@ static struct sk_buff *xsk_build_skb(struct xdp_sock *xs, if (!skb) { hr = max(NET_SKB_PAD, L1_CACHE_ALIGN(dev->needed_headroom)); - tr = dev->needed_tailroom; - skb = sock_alloc_send_skb(&xs->sk, hr + len + tr, 1, &err); + if (!allocated_skb) { + tr = dev->needed_tailroom; + skb = sock_alloc_send_skb(&xs->sk, hr + len + tr, 1, &err); + } else { + skb = allocated_skb; + } if (unlikely(!skb)) goto free_err; @@ -943,7 +952,7 @@ static int __xsk_generic_xmit(struct sock *sk) goto out; } - skb = xsk_build_skb(xs, &desc); + skb = xsk_build_skb(xs, NULL, &desc); if (IS_ERR(skb)) { err = PTR_ERR(skb); if (err != -EOVERFLOW) -- 2.41.3