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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni Cc: David Howells , Al Viro , Christoph Hellwig , Jens Axboe , Jeff Layton , Christian Brauner , Chuck Lever III , Linus Torvalds , netdev@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: [RFC PATCH v2 35/48] net: Use sendmsg(MSG_SPLICE_PAGES) not sendpage in skb_send_sock() Date: Wed, 29 Mar 2023 15:13:41 +0100 Message-Id: <20230329141354.516864-36-dhowells@redhat.com> In-Reply-To: <20230329141354.516864-1-dhowells@redhat.com> References: <20230329141354.516864-1-dhowells@redhat.com> MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.1 on 10.11.54.4 X-Rspamd-Queue-Id: 561D140005 X-Rspamd-Server: rspam09 X-Rspam-User: X-Stat-Signature: j9u65jh86m8jexuo9zc8ii4syykkkp8b X-HE-Tag: 1680099343-965657 X-HE-Meta: U2FsdGVkX19+BAeDWq5dHzsPgQ9Wn569Vo7PPIpegCxalgPmU0imknkCBk9PKokLtn+pi5Ioyd3k226pPbbIXX19lDbJUVwxjy9aIleTrea/C1czqetJq7hqV8kCUyiT43Kjz8wLoUTFXM9te1iW6rGqi0/KeAMsJkN8b65dM0JTnUjD8RQm9pMtyl7kSKSH8H+wKr/xCJq89Xm0qmtQXeZDGI0K/GH7w0efMBZnG5gK0eQOR91Jgz+0m/ZrosGMesyVzgjMcE4OZqdBiIPFxGGPW3ygJVKoi130wbEsnZaX1F4O6Fi9hJRjI5FrlVIAXiczZFxWCzxz54VA0UbiwguvD7oxayjBMbB8+vOat1lJK+XudmO8mp2/Ajllwab2K/pdazm/FWGaQooGVJHx1hAKbd80zieCOvG5SPbHnb+UJL+C1QWsdsmUrWpBuR7SVrlW6xiBaaBAmK9iFxS3S81mdciGnLLu3pNahDqSa+qaMZBKZZbs7ACgMXup+beD8bXxCNTIMtfj98TFRcMm26kEe+8hSoobivlMAIJ+nwDDHiS7tQyXi9BztS92FegDpj3epcE+qlWVyRDgcL9DN6VQTdgX5y5AICwt2GeX8NpUzdHG3bCj88ks+lYuuF0GLZ01h1oXY1H14EyJCWfc1ixJxgwb7bGMq7wo6mJU5hDqq9EYj58YPmXdokc3nilxtApdQbRtZGwj6PMmr/1c7a0bjgQTLR1QA6tsLrnPFOx4b5vHpDdAQqCh05uLyIR/b0I/j+qTuJq8tcW/aJ52r+c4lk/4a0PhTAYci+ZqiomUiONMEQkf9eohbn9/Qu03BwAQ3V523kIfp2mBVLRLZ4tBBxYHTEx5HsghFfRhq1nJnExKBImWQ198NpPdgWJE/2C0Ldg7Z7naREXbE5eWM/49+kK5WVAgXC3e9rbd/hqzBJhdKHFn1J0VnIDRZPZxrC5Xk04u0S/K44ikG8E jwDREv7k N2vWP7HaPiBvSHPP+iNySjwrt/eagVAre2HC2xLuV8itYTSDwWRXgcOV+MQVPaxhH2Z0Z/3TP6NZWxxB1nl6WrFuvba1T0ri74W0wuGSe7+rQilm2j2mNBDK3XTBjjeVJitiw1NHCx/9LWXK89NuzRAE5VicfvpsxFz7PX3fy/B6Ruqeo9v60c3ik0cHoxiJibq2OdwqZ5XJM572N/8jNU9uzJ2GS2J+Zf1psTYnhQBJff05OIKSm8J+Qj4NZb0LI2tFKDtOlpNGz+dVqmNjACYski82awU8inmM+2zRyXryY6cCf1kUrbBT9oqy9zysjIAcuE4f5KhtAPVeFRqMmB4VJ+avmlDE2REi5sA9S4d9Z7aivR+2tjl9P7qOeeN3YH/U6eTrAVt+zNkOVIYCtXrPmzvYKM5pxH1rQZvWC59nsPRfes0cQaHftV9yQ80fW4nMs X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: Use sendmsg() with MSG_SPLICE_PAGES rather than sendpage in skb_send_sock(). This causes pages to be spliced from the source iterator if possible (the iterator must be ITER_BVEC and the pages must be spliceable). This allows ->sendpage() to be replaced by something that can handle multiple multipage folios in a single transaction. Note that this could perhaps be improved to fill out a bvec array with all the frags and then make a single sendmsg call, possibly sticking the header on the front also. Signed-off-by: David Howells cc: "David S. Miller" cc: Eric Dumazet cc: Jakub Kicinski cc: Paolo Abeni cc: Jens Axboe cc: Matthew Wilcox cc: netdev@vger.kernel.org --- net/core/skbuff.c | 49 ++++++++++++++++++++++++++--------------------- 1 file changed, 27 insertions(+), 22 deletions(-) diff --git a/net/core/skbuff.c b/net/core/skbuff.c index 0506e4cf1ed9..3693b3526d33 100644 --- a/net/core/skbuff.c +++ b/net/core/skbuff.c @@ -2919,32 +2919,32 @@ int skb_splice_bits(struct sk_buff *skb, struct sock *sk, unsigned int offset, } EXPORT_SYMBOL_GPL(skb_splice_bits); -static int sendmsg_unlocked(struct sock *sk, struct msghdr *msg, - struct kvec *vec, size_t num, size_t size) +static int sendmsg_locked(struct sock *sk, struct msghdr *msg) { struct socket *sock = sk->sk_socket; + size_t size = msg_data_left(msg); if (!sock) return -EINVAL; - return kernel_sendmsg(sock, msg, vec, num, size); + + if (!sock->ops->sendmsg_locked) + return sock_no_sendmsg_locked(sk, msg, size); + + return sock->ops->sendmsg_locked(sk, msg, size); } -static int sendpage_unlocked(struct sock *sk, struct page *page, int offset, - size_t size, int flags) +static int sendmsg_unlocked(struct sock *sk, struct msghdr *msg) { struct socket *sock = sk->sk_socket; if (!sock) return -EINVAL; - return kernel_sendpage(sock, page, offset, size, flags); + return sock_sendmsg(sock, msg); } -typedef int (*sendmsg_func)(struct sock *sk, struct msghdr *msg, - struct kvec *vec, size_t num, size_t size); -typedef int (*sendpage_func)(struct sock *sk, struct page *page, int offset, - size_t size, int flags); +typedef int (*sendmsg_func)(struct sock *sk, struct msghdr *msg); static int __skb_send_sock(struct sock *sk, struct sk_buff *skb, int offset, - int len, sendmsg_func sendmsg, sendpage_func sendpage) + int len, sendmsg_func sendmsg) { unsigned int orig_len = len; struct sk_buff *head = skb; @@ -2964,8 +2964,9 @@ static int __skb_send_sock(struct sock *sk, struct sk_buff *skb, int offset, memset(&msg, 0, sizeof(msg)); msg.msg_flags = MSG_DONTWAIT; - ret = INDIRECT_CALL_2(sendmsg, kernel_sendmsg_locked, - sendmsg_unlocked, sk, &msg, &kv, 1, slen); + iov_iter_kvec(&msg.msg_iter, ITER_SOURCE, &kv, 1, slen); + ret = INDIRECT_CALL_2(sendmsg, sendmsg_locked, + sendmsg_unlocked, sk, &msg); if (ret <= 0) goto error; @@ -2996,11 +2997,17 @@ static int __skb_send_sock(struct sock *sk, struct sk_buff *skb, int offset, slen = min_t(size_t, len, skb_frag_size(frag) - offset); while (slen) { - ret = INDIRECT_CALL_2(sendpage, kernel_sendpage_locked, - sendpage_unlocked, sk, - skb_frag_page(frag), - skb_frag_off(frag) + offset, - slen, MSG_DONTWAIT); + struct bio_vec bvec; + struct msghdr msg = { + .msg_flags = MSG_SPLICE_PAGES | MSG_DONTWAIT, + }; + + bvec_set_page(&bvec, skb_frag_page(frag), slen, + skb_frag_off(frag) + offset); + iov_iter_bvec(&msg.msg_iter, ITER_SOURCE, &bvec, 1, slen); + + ret = INDIRECT_CALL_2(sendmsg, sendmsg_locked, + sendmsg_unlocked, sk, &msg); if (ret <= 0) goto error; @@ -3037,16 +3044,14 @@ static int __skb_send_sock(struct sock *sk, struct sk_buff *skb, int offset, int skb_send_sock_locked(struct sock *sk, struct sk_buff *skb, int offset, int len) { - return __skb_send_sock(sk, skb, offset, len, kernel_sendmsg_locked, - kernel_sendpage_locked); + return __skb_send_sock(sk, skb, offset, len, sendmsg_locked); } EXPORT_SYMBOL_GPL(skb_send_sock_locked); /* Send skb data on a socket. Socket must be unlocked. */ int skb_send_sock(struct sock *sk, struct sk_buff *skb, int offset, int len) { - return __skb_send_sock(sk, skb, offset, len, sendmsg_unlocked, - sendpage_unlocked); + return __skb_send_sock(sk, skb, offset, len, sendmsg_unlocked); } /**