/** * skb_copy_datagram_iter - Copy a datagram to an iovec iterator. * @skb: buffer to copy * @offset: offset in the buffer to start copying from * @to: iovec iterator to copy to * @len: amount of data to copy from buffer to iovec */ int skb_copy_datagram_iter(const struct sk_buff *skb, int offset, struct iov_iter *to, int len) { int start = skb_headlen(skb); int i, copy = start - offset, start_off = offset, n; struct sk_buff *frag_iter; trace_skb_copy_datagram_iovec(skb, len); /* Copy header. */ if (copy > 0) { if (copy > len) copy = len; n = copy_to_iter(skb->data + offset, copy, to); offset += n; if (n != copy) goto short_copy; if ((len -= copy) == 0) return 0; } /* Copy paged appendix. Hmm... why does this look so complicated? */ for (i = 0; i < skb_shinfo(skb)->nr_frags; i++) { int end; const skb_frag_t *frag = &skb_shinfo(skb)->frags[i]; WARN_ON(start > offset + len); end = start + skb_frag_size(frag); if ((copy = end - offset) > 0) { if (copy > len) copy = len; n = copy_page_to_iter(skb_frag_page(frag), frag->page_offset + offset - start, copy, to); offset += n; if (n != copy) goto short_copy; if (!(len -= copy)) return 0; } start = end; } skb_walk_frags(skb, frag_iter) { int end; WARN_ON(start > offset + len); end = start + frag_iter->len; if ((copy = end - offset) > 0) { if (copy > len) copy = len; if (skb_copy_datagram_iter(frag_iter, offset - start, to, copy)) goto fault; if ((len -= copy) == 0) return 0; offset += copy; } start = end; }
/* * Deliver messages to a call. This keeps processing packets until the buffer * is filled and we find either more DATA (returns 0) or the end of the DATA * (returns 1). If more packets are required, it returns -EAGAIN. */ static int rxrpc_recvmsg_data(struct socket *sock, struct rxrpc_call *call, struct msghdr *msg, struct iov_iter *iter, size_t len, int flags, size_t *_offset) { struct rxrpc_skb_priv *sp; struct sk_buff *skb; rxrpc_seq_t hard_ack, top, seq; size_t remain; bool last; unsigned int rx_pkt_offset, rx_pkt_len; int ix, copy, ret = -EAGAIN, ret2; rx_pkt_offset = call->rx_pkt_offset; rx_pkt_len = call->rx_pkt_len; if (call->state >= RXRPC_CALL_SERVER_ACK_REQUEST) { seq = call->rx_hard_ack; ret = 1; goto done; } /* Barriers against rxrpc_input_data(). */ hard_ack = call->rx_hard_ack; top = smp_load_acquire(&call->rx_top); for (seq = hard_ack + 1; before_eq(seq, top); seq++) { ix = seq & RXRPC_RXTX_BUFF_MASK; skb = call->rxtx_buffer[ix]; if (!skb) { trace_rxrpc_recvmsg(call, rxrpc_recvmsg_hole, seq, rx_pkt_offset, rx_pkt_len, 0); break; } smp_rmb(); rxrpc_see_skb(skb, rxrpc_skb_rx_seen); sp = rxrpc_skb(skb); if (!(flags & MSG_PEEK)) trace_rxrpc_receive(call, rxrpc_receive_front, sp->hdr.serial, seq); if (msg) sock_recv_timestamp(msg, sock->sk, skb); if (rx_pkt_offset == 0) { ret2 = rxrpc_locate_data(call, skb, &call->rxtx_annotations[ix], &rx_pkt_offset, &rx_pkt_len); trace_rxrpc_recvmsg(call, rxrpc_recvmsg_next, seq, rx_pkt_offset, rx_pkt_len, ret2); if (ret2 < 0) { ret = ret2; goto out; } } else { trace_rxrpc_recvmsg(call, rxrpc_recvmsg_cont, seq, rx_pkt_offset, rx_pkt_len, 0); } /* We have to handle short, empty and used-up DATA packets. */ remain = len - *_offset; copy = rx_pkt_len; if (copy > remain) copy = remain; if (copy > 0) { ret2 = skb_copy_datagram_iter(skb, rx_pkt_offset, iter, copy); if (ret2 < 0) { ret = ret2; goto out; } /* handle piecemeal consumption of data packets */ rx_pkt_offset += copy; rx_pkt_len -= copy; *_offset += copy; } if (rx_pkt_len > 0) { trace_rxrpc_recvmsg(call, rxrpc_recvmsg_full, seq, rx_pkt_offset, rx_pkt_len, 0); ASSERTCMP(*_offset, ==, len); ret = 0; break; } /* The whole packet has been transferred. */ last = sp->hdr.flags & RXRPC_LAST_PACKET; if (!(flags & MSG_PEEK)) rxrpc_rotate_rx_window(call); rx_pkt_offset = 0; rx_pkt_len = 0; if (last) { ASSERTCMP(seq, ==, READ_ONCE(call->rx_top)); ret = 1; goto out; } }