Merge branch 'splice-net-handle-msg_splice_pages-in-af_kcm'
David Howells says: ==================== splice, net: Handle MSG_SPLICE_PAGES in AF_KCM Here are patches to make AF_KCM handle the MSG_SPLICE_PAGES internal sendmsg flag. MSG_SPLICE_PAGES is an internal hint that tells the protocol that it should splice the pages supplied if it can. Its sendpage implementation is then turned into a wrapper around that. Does anyone actually use AF_KCM? Upstream it has some issues. It doesn't seem able to handle a "message" longer than 113920 bytes without jamming and doesn't handle the client termination once it is jammed. Link: https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git/commit/?id=51c78a4d532efe9543a4df019ff405f05c6157f6 # part 1 Link: https://lore.kernel.org/r/20230524144923.3623536-1-dhowells@redhat.com/ # v1 ==================== Link: https://lore.kernel.org/r/20230531110423.643196-1-dhowells@redhat.com Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This commit is contained in:
Jakub Kicinski
commit
ddb8701dcb
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@ -761,149 +761,6 @@ static void kcm_push(struct kcm_sock *kcm)
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kcm_write_msgs(kcm);
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}
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static ssize_t kcm_sendpage(struct socket *sock, struct page *page,
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int offset, size_t size, int flags)
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{
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struct sock *sk = sock->sk;
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struct kcm_sock *kcm = kcm_sk(sk);
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struct sk_buff *skb = NULL, *head = NULL;
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long timeo = sock_sndtimeo(sk, flags & MSG_DONTWAIT);
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bool eor;
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int err = 0;
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int i;
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if (flags & MSG_SENDPAGE_NOTLAST)
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flags |= MSG_MORE;
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/* No MSG_EOR from splice, only look at MSG_MORE */
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eor = !(flags & MSG_MORE);
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lock_sock(sk);
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sk_clear_bit(SOCKWQ_ASYNC_NOSPACE, sk);
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err = -EPIPE;
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if (sk->sk_err)
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goto out_error;
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if (kcm->seq_skb) {
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/* Previously opened message */
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head = kcm->seq_skb;
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skb = kcm_tx_msg(head)->last_skb;
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i = skb_shinfo(skb)->nr_frags;
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if (skb_can_coalesce(skb, i, page, offset)) {
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skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], size);
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skb_shinfo(skb)->flags |= SKBFL_SHARED_FRAG;
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goto coalesced;
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}
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if (i >= MAX_SKB_FRAGS) {
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struct sk_buff *tskb;
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tskb = alloc_skb(0, sk->sk_allocation);
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while (!tskb) {
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kcm_push(kcm);
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err = sk_stream_wait_memory(sk, &timeo);
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if (err)
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goto out_error;
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}
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if (head == skb)
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skb_shinfo(head)->frag_list = tskb;
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else
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skb->next = tskb;
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skb = tskb;
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skb->ip_summed = CHECKSUM_UNNECESSARY;
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i = 0;
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}
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} else {
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/* Call the sk_stream functions to manage the sndbuf mem. */
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if (!sk_stream_memory_free(sk)) {
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kcm_push(kcm);
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set_bit(SOCK_NOSPACE, &sk->sk_socket->flags);
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err = sk_stream_wait_memory(sk, &timeo);
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if (err)
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goto out_error;
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}
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head = alloc_skb(0, sk->sk_allocation);
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while (!head) {
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kcm_push(kcm);
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err = sk_stream_wait_memory(sk, &timeo);
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if (err)
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goto out_error;
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}
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skb = head;
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i = 0;
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}
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get_page(page);
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skb_fill_page_desc_noacc(skb, i, page, offset, size);
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skb_shinfo(skb)->flags |= SKBFL_SHARED_FRAG;
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coalesced:
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skb->len += size;
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skb->data_len += size;
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skb->truesize += size;
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sk->sk_wmem_queued += size;
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sk_mem_charge(sk, size);
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if (head != skb) {
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head->len += size;
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head->data_len += size;
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head->truesize += size;
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}
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if (eor) {
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bool not_busy = skb_queue_empty(&sk->sk_write_queue);
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/* Message complete, queue it on send buffer */
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__skb_queue_tail(&sk->sk_write_queue, head);
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kcm->seq_skb = NULL;
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KCM_STATS_INCR(kcm->stats.tx_msgs);
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if (flags & MSG_BATCH) {
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kcm->tx_wait_more = true;
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} else if (kcm->tx_wait_more || not_busy) {
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err = kcm_write_msgs(kcm);
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if (err < 0) {
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/* We got a hard error in write_msgs but have
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* already queued this message. Report an error
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* in the socket, but don't affect return value
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* from sendmsg
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*/
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pr_warn("KCM: Hard failure on kcm_write_msgs\n");
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report_csk_error(&kcm->sk, -err);
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}
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}
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} else {
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/* Message not complete, save state */
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kcm->seq_skb = head;
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kcm_tx_msg(head)->last_skb = skb;
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}
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KCM_STATS_ADD(kcm->stats.tx_bytes, size);
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release_sock(sk);
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return size;
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out_error:
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kcm_push(kcm);
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err = sk_stream_error(sk, flags, err);
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/* make sure we wake any epoll edge trigger waiter */
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if (unlikely(skb_queue_len(&sk->sk_write_queue) == 0 && err == -EAGAIN))
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sk->sk_write_space(sk);
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release_sock(sk);
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return err;
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}
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static int kcm_sendmsg(struct socket *sock, struct msghdr *msg, size_t len)
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{
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struct sock *sk = sock->sk;
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@ -989,29 +846,52 @@ start:
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merge = false;
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}
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copy = min_t(int, msg_data_left(msg),
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pfrag->size - pfrag->offset);
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if (msg->msg_flags & MSG_SPLICE_PAGES) {
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copy = msg_data_left(msg);
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if (!sk_wmem_schedule(sk, copy))
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goto wait_for_memory;
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if (!sk_wmem_schedule(sk, copy))
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goto wait_for_memory;
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err = skb_splice_from_iter(skb, &msg->msg_iter, copy,
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sk->sk_allocation);
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if (err < 0) {
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if (err == -EMSGSIZE)
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goto wait_for_memory;
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goto out_error;
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}
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err = skb_copy_to_page_nocache(sk, &msg->msg_iter, skb,
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pfrag->page,
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pfrag->offset,
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copy);
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if (err)
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goto out_error;
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copy = err;
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skb_shinfo(skb)->flags |= SKBFL_SHARED_FRAG;
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sk_wmem_queued_add(sk, copy);
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sk_mem_charge(sk, copy);
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/* Update the skb. */
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if (merge) {
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skb_frag_size_add(&skb_shinfo(skb)->frags[i - 1], copy);
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if (head != skb)
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head->truesize += copy;
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} else {
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skb_fill_page_desc(skb, i, pfrag->page,
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pfrag->offset, copy);
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get_page(pfrag->page);
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copy = min_t(int, msg_data_left(msg),
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pfrag->size - pfrag->offset);
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if (!sk_wmem_schedule(sk, copy))
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goto wait_for_memory;
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err = skb_copy_to_page_nocache(sk, &msg->msg_iter, skb,
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pfrag->page,
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pfrag->offset,
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copy);
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if (err)
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goto out_error;
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/* Update the skb. */
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if (merge) {
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skb_frag_size_add(
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&skb_shinfo(skb)->frags[i - 1], copy);
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} else {
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skb_fill_page_desc(skb, i, pfrag->page,
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pfrag->offset, copy);
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get_page(pfrag->page);
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}
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pfrag->offset += copy;
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}
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pfrag->offset += copy;
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copied += copy;
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if (head != skb) {
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head->len += copy;
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@ -1088,6 +968,24 @@ out_error:
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return err;
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}
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static ssize_t kcm_sendpage(struct socket *sock, struct page *page,
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int offset, size_t size, int flags)
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{
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struct bio_vec bvec;
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struct msghdr msg = { .msg_flags = flags | MSG_SPLICE_PAGES, };
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if (flags & MSG_SENDPAGE_NOTLAST)
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msg.msg_flags |= MSG_MORE;
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if (flags & MSG_OOB)
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return -EOPNOTSUPP;
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bvec_set_page(&bvec, page, size, offset);
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iov_iter_bvec(&msg.msg_iter, ITER_SOURCE, &bvec, 1, size);
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return kcm_sendmsg(sock, &msg, size);
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}
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static int kcm_recvmsg(struct socket *sock, struct msghdr *msg,
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size_t len, int flags)
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{
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