net: refactor packet queueing code

The packet queue code is fairly standalone, has some complex details and
easily reusable. It makes sense to split it out on its own. This patch
doesn't contain any functional changes.

Patchworks-ID: 35511
Signed-off-by: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

1 files changed, 250 insertions, 0 deletions

diff --git a/net-queue.c b/net-queue.c
new file mode 100644
index 0000000000..75457f07e9
--- /dev/null
+++ b/net-queue.c
@@ -0,0 +1,250 @@
+/*
+ * Copyright (c) 2003-2008 Fabrice Bellard
+ * Copyright (c) 2009 Red Hat, Inc.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+ * THE SOFTWARE.
+ */
+
+#include "net-queue.h"
+#include "qemu-queue.h"
+
+/* The delivery handler may only return zero if it will call
+ * qemu_net_queue_flush() when it determines that it is once again able
+ * to deliver packets. It must also call qemu_net_queue_purge() in its
+ * cleanup path.
+ *
+ * If a sent callback is provided to send(), the caller must handle a
+ * zero return from the delivery handler by not sending any more packets
+ * until we have invoked the callback. Only in that case will we queue
+ * the packet.
+ *
+ * If a sent callback isn't provided, we just drop the packet to avoid
+ * unbounded queueing.
+ */
+
+struct NetPacket {
+    QTAILQ_ENTRY(NetPacket) entry;
+    VLANClientState *sender;
+    int size;
+    NetPacketSent *sent_cb;
+    uint8_t data[0];
+};
+
+struct NetQueue {
+    NetPacketDeliver *deliver;
+    NetPacketDeliverIOV *deliver_iov;
+    void *opaque;
+
+    QTAILQ_HEAD(packets, NetPacket) packets;
+
+    unsigned delivering : 1;
+};
+
+NetQueue *qemu_new_net_queue(NetPacketDeliver *deliver,
+                             NetPacketDeliverIOV *deliver_iov,
+                             void *opaque)
+{
+    NetQueue *queue;
+
+    queue = qemu_mallocz(sizeof(NetQueue));
+
+    queue->deliver = deliver;
+    queue->deliver_iov = deliver_iov;
+    queue->opaque = opaque;
+
+    QTAILQ_INIT(&queue->packets);
+
+    queue->delivering = 0;
+
+    return queue;
+}
+
+void qemu_del_net_queue(NetQueue *queue)
+{
+    NetPacket *packet, *next;
+
+    QTAILQ_FOREACH_SAFE(packet, &queue->packets, entry, next) {
+        QTAILQ_REMOVE(&queue->packets, packet, entry);
+        qemu_free(packet);
+    }
+
+    qemu_free(queue);
+}
+
+static ssize_t qemu_net_queue_append(NetQueue *queue,
+                                     VLANClientState *sender,
+                                     const uint8_t *buf,
+                                     size_t size,
+                                     NetPacketSent *sent_cb)
+{
+    NetPacket *packet;
+
+    packet = qemu_malloc(sizeof(NetPacket) + size);
+    packet->sender = sender;
+    packet->size = size;
+    packet->sent_cb = sent_cb;
+    memcpy(packet->data, buf, size);
+
+    QTAILQ_INSERT_TAIL(&queue->packets, packet, entry);
+
+    return size;
+}
+
+static ssize_t qemu_net_queue_append_iov(NetQueue *queue,
+                                         VLANClientState *sender,
+                                         const struct iovec *iov,
+                                         int iovcnt,
+                                         NetPacketSent *sent_cb)
+{
+    NetPacket *packet;
+    size_t max_len = 0;
+    int i;
+
+    for (i = 0; i < iovcnt; i++) {
+        max_len += iov[i].iov_len;
+    }
+
+    packet = qemu_malloc(sizeof(NetPacket) + max_len);
+    packet->sender = sender;
+    packet->sent_cb = sent_cb;
+    packet->size = 0;
+
+    for (i = 0; i < iovcnt; i++) {
+        size_t len = iov[i].iov_len;
+
+        memcpy(packet->data + packet->size, iov[i].iov_base, len);
+        packet->size += len;
+    }
+
+    QTAILQ_INSERT_TAIL(&queue->packets, packet, entry);
+
+    return packet->size;
+}
+
+static ssize_t qemu_net_queue_deliver(NetQueue *queue,
+                                      VLANClientState *sender,
+                                      const uint8_t *data,
+                                      size_t size)
+{
+    ssize_t ret = -1;
+
+    queue->delivering = 1;
+    ret = queue->deliver(sender, data, size, queue->opaque);
+    queue->delivering = 0;
+
+    return ret;
+}
+
+static ssize_t qemu_net_queue_deliver_iov(NetQueue *queue,
+                                          VLANClientState *sender,
+                                          const struct iovec *iov,
+                                          int iovcnt)
+{
+    ssize_t ret = -1;
+
+    queue->delivering = 1;
+    ret = queue->deliver_iov(sender, iov, iovcnt, queue->opaque);
+    queue->delivering = 0;
+
+    return ret;
+}
+
+ssize_t qemu_net_queue_send(NetQueue *queue,
+                            VLANClientState *sender,
+                            const uint8_t *data,
+                            size_t size,
+                            NetPacketSent *sent_cb)
+{
+    ssize_t ret;
+
+    if (queue->delivering) {
+        return qemu_net_queue_append(queue, sender, data, size, NULL);
+    }
+
+    ret = qemu_net_queue_deliver(queue, sender, data, size);
+    if (ret == 0 && sent_cb != NULL) {
+        qemu_net_queue_append(queue, sender, data, size, sent_cb);
+        return 0;
+    }
+
+    qemu_net_queue_flush(queue);
+
+    return ret;
+}
+
+ssize_t qemu_net_queue_send_iov(NetQueue *queue,
+                                VLANClientState *sender,
+                                const struct iovec *iov,
+                                int iovcnt,
+                                NetPacketSent *sent_cb)
+{
+    ssize_t ret;
+
+    if (queue->delivering) {
+        return qemu_net_queue_append_iov(queue, sender, iov, iovcnt, NULL);
+    }
+
+    ret = qemu_net_queue_deliver_iov(queue, sender, iov, iovcnt);
+    if (ret == 0 && sent_cb != NULL) {
+        qemu_net_queue_append_iov(queue, sender, iov, iovcnt, sent_cb);
+        return 0;
+    }
+
+    qemu_net_queue_flush(queue);
+
+    return ret;
+}
+
+void qemu_net_queue_purge(NetQueue *queue, VLANClientState *from)
+{
+    NetPacket *packet, *next;
+
+    QTAILQ_FOREACH_SAFE(packet, &queue->packets, entry, next) {
+        if (packet->sender == from) {
+            QTAILQ_REMOVE(&queue->packets, packet, entry);
+            qemu_free(packet);
+        }
+    }
+}
+
+void qemu_net_queue_flush(NetQueue *queue)
+{
+    while (!QTAILQ_EMPTY(&queue->packets)) {
+        NetPacket *packet;
+        int ret;
+
+        packet = QTAILQ_FIRST(&queue->packets);
+        QTAILQ_REMOVE(&queue->packets, packet, entry);
+
+        ret = qemu_net_queue_deliver(queue,
+                                     packet->sender,
+                                     packet->data,
+                                     packet->size);
+        if (ret == 0 && packet->sent_cb != NULL) {
+            QTAILQ_INSERT_HEAD(&queue->packets, packet, entry);
+            break;
+        }
+
+        if (packet->sent_cb) {
+            packet->sent_cb(packet->sender, ret);
+        }
+
+        qemu_free(packet);
+    }
+}