Re: [Qemu-devel] [RFC PATCH 7/9] net/colo-proxy: add packet enqueue and handle function

["Dr. David Alan Gilbert" <dgilbert@redhat.com>]

* Zhang Chen (zhangchen.fnst@cn.fujitsu.com) wrote:
> Hi,Dave
> 
> 
> On 12/03/2015 05:09 PM, Dr. David Alan Gilbert wrote:
> >* Zhang Chen (zhangchen.fnst@cn.fujitsu.com) wrote:
> >>Hi,Dave
> >>
> >>On 12/02/2015 12:12 AM, Dr. David Alan Gilbert wrote:
> >>>* Zhang Chen (zhangchen.fnst@cn.fujitsu.com) wrote:
> >>>>From: zhangchen <zhangchen.fnst@cn.fujitsu.com>
> >>>>
> >>>>Add common packet handle function and enqueue
> >>>>packet distinguished connection,then we can
> >>>>lookup one connection packet to compare
> >>>>
> >>>>Signed-off-by: zhangchen <zhangchen.fnst@cn.fujitsu.com>
> >>>>---
> >>>>  net/colo-proxy.c | 167 ++++++++++++++++++++++++++++++++++++++++++++++++++++++-
> >>>>  1 file changed, 166 insertions(+), 1 deletion(-)
> >>>>
> >>>>diff --git a/net/colo-proxy.c b/net/colo-proxy.c
> >>>>index 08a852f..a664e6d 100644
> >>>>--- a/net/colo-proxy.c
> >>>>+++ b/net/colo-proxy.c
> >>>>@@ -24,6 +24,170 @@
> >>>>  static char *mode;
> >>>>  static bool colo_do_checkpoint;
> >>>>+static void packet_destroy(void *opaque, void *user_data);
> >>>>+
> >>>>+static uint32_t connection_key_hash(const void *opaque)
> >>>>+{
> >>>>+    const Connection_key *key = opaque;
> >>>>+    uint32_t a, b, c;
> >>>>+
> >>>>+    /* Jenkins hash */
> >>>>+    a = b = c = JHASH_INITVAL + sizeof(*key);
> >>>>+    a += key->src;
> >>>>+    b += key->dst;
> >>>>+    c += key->ports;
> >>>>+    __jhash_mix(a, b, c);
> >>>>+
> >>>>+    a += key->ip_proto;
> >>>>+    __jhash_final(a, b, c);
> >>>>+
> >>>>+    return c;
> >>>>+}
> >>>>+
> >>>>+static int connection_key_equal(const void *opaque1, const void *opaque2)
> >>>>+{
> >>>>+    return memcmp(opaque1, opaque2, sizeof(Connection_key)) == 0;
> >>>>+}
> >>>>+
> >>>>+static void connection_destroy(void *opaque)
> >>>>+{
> >>>>+    Connection *connection = opaque;
> >>>>+    g_queue_foreach(&connection->primary_list, packet_destroy, NULL);
> >>>>+    g_queue_free(&connection->primary_list);
> >>>>+    g_queue_foreach(&connection->secondary_list, packet_destroy, NULL);
> >>>>+    g_queue_free(&connection->secondary_list);
> >>>>+    g_slice_free(Connection, connection);
> >>>>+}
> >>>>+
> >>>>+static Connection *connection_new(void)
> >>>>+{
> >>>>+    Connection *connection = g_slice_new(Connection);
> >>>>+
> >>>>+    g_queue_init(&connection->primary_list);
> >>>>+    g_queue_init(&connection->secondary_list);
> >>>>+    connection->processing = false;
> >>>>+
> >>>>+    return connection;
> >>>>+}
> >>>>+
> >>>>+/* Return 0 on success, or return -1 if the pkt is corrpted */
> >>>>+static int parse_packet_early(Packet *pkt, Connection_key *key)
> >>>>+{
> >>>>+    int network_length;
> >>>>+    uint8_t *data = pkt->data;
> >>>>+
> >>>>+    pkt->network_layer = data + ETH_HLEN;
> >>>>+    if (ntohs(*(uint16_t *)(data + 12)) != ETH_P_IP) {
> >>>>+        if (ntohs(*(uint16_t *)(data + 12)) == ETH_P_ARP) {
> >>>>+            return -1;
> >>>>+        }
> >>>>+        return 0;
> >>>>+    }
> >>>Can you use some of the functions/macros in include/net/eth.h to
> >>>make this easier? Maybe eth_get_l3_proto ?
> >>>Do you plan to do IPv6 at some point?
> >>I will use include/net/eth.h in next version
> >>
> >>IPv6 currently not support, still colo framework be merged
> >>
> >>>>+    network_length = pkt->ip->ip_hl * 4;
> >>>>+    pkt->transport_layer = pkt->network_layer + network_length;
> >>>>+    key->ip_proto = pkt->ip->ip_p;
> >>>>+    key->src = pkt->ip->ip_src;
> >>>>+    key->dst = pkt->ip->ip_dst;
> >>>>+
> >>>>+    switch (key->ip_proto) {
> >>>>+    case IPPROTO_TCP:
> >>>>+    case IPPROTO_UDP:
> >>>>+    case IPPROTO_DCCP:
> >>>>+    case IPPROTO_ESP:
> >>>>+    case IPPROTO_SCTP:
> >>>>+    case IPPROTO_UDPLITE:
> >>>>+        key->ports = *(uint32_t *)(pkt->transport_layer);
> >>>>+        break;
> >>>>+    case IPPROTO_AH:
> >>>>+        key->ports = *(uint32_t *)(pkt->transport_layer + 4);
> >>>Interesting; I don't see any other code in QEMU to handle AH,
> >>>and I don't know much about it.
> >>>
> >>>>+        break;
> >>>>+    default:
> >>>>+        break;
> >>>>+    }
> >>>>+
> >>>>+    return 0;
> >>>>+}
> >>>>+
> >>>>+static Packet *packet_new(ColoProxyState *s, const void *data,
> >>>>+                          int size, Connection_key *key, NetClientState *sender)
> >>>>+{
> >>>>+    Packet *pkt = g_slice_new(Packet);
> >>>>+
> >>>>+    pkt->data = g_malloc(size);
> >>>>+    memcpy(pkt->data, data, size);
> >>>g_memdup might be useful for these:
> >>>https://developer.gnome.org/glib/stable/glib-Memory-Allocation.html#g-memdup
> >>I will fix it in next version
> >>
> >>>>+    pkt->size = size;
> >>>>+    pkt->s = s;
> >>>>+    pkt->sender = sender;
> >>>>+    pkt->should_be_sent = false;
> >>>>+
> >>>>+    if (parse_packet_early(pkt, key)) {
> >>>>+        packet_destroy(pkt, NULL);
> >>>>+        pkt = NULL;
> >>>>+    }
> >>>>+
> >>>>+    return pkt;
> >>>>+}
> >>>>+
> >>>>+static void packet_destroy(void *opaque, void *user_data)
> >>>>+{
> >>>>+    Packet *pkt = opaque;
> >>>>+    g_free(pkt->data);
> >>>>+    g_slice_free(Packet, pkt);
> >>>>+}
> >>>>+
> >>>>+static Connection *colo_proxy_enqueue_packet(GHashTable *unprocessed_packets,
> >>>>+                                          Connection_key *key,
> >>>>+                                          Packet *pkt, packet_type type)
> >>>>+{
> >>>>+    Connection *connection;
> >>>>+    Packet *tmppkt;
> >>>>+    connection = g_hash_table_lookup(unprocessed_packets, key);
> >>>>+    if (connection == NULL) {
> >>>>+        Connection_key *new_key = g_malloc(sizeof(*key));
> >>>>+
> >>>>+        connection = connection_new();
> >>>>+        memcpy(new_key, key, sizeof(*key));
> >>>>+        key = new_key;
> >>>>+
> >>>>+        g_hash_table_insert(unprocessed_packets, key, connection);
> >>>Is 'unprocessed_packets' a good name for this hashtable? I'm not quite
> >>>sure I understand, but it looks to me like it's your connection-tracking equivalent,
> >>>which then has a queue for each connection with unprocessed packets?
> >>i will change hashtable name to connection_track_table,is it ok?
> >Yes, thank you.
> >
> >>>Also, do we do anything to stop this hash growing really huge? If there
> >>>are lots-and-lots of connections can we limit it somehow? (what does Linux do?)
> >>when we find PVM's packet different to SVM's packet,colo will do checkpoint.
> >>that's means we will flush all connection's packets,even though all packets
> >>are
> >>same,colo will alse do checkpoint periodically. so hashtable can't growing
> >>really huge.
> >I see the flush clears all the packets, but does it also clear the hash?
> >
> 
> I read the kernel code,TCP conntrack will clear hash one time every five
> days periodicity.
> and the hashtable size
>     /* Idea from tcp.c: use 1/16384 of memory.  On i386: 32MB
>      * machine has 512 buckets. >= 1GB machines have 16384 buckets. */
> I will follow kernel's done to fix colo-proxy in next version.

I think it's OK if you just set a size and make it limit to that size;
lets keep it simple for now.   I think you'll also have to free entries
when you see the TCP connection closed.


Dave

> 
> Thanks for review
> zhangchen
> 
> >>>>+    }
> >>>>+    switch (type) {
> >>>>+    case PRIMARY_OUTPUT:
> >>>>+        if (g_queue_get_length(&connection->secondary_list) > 0) {
> >>>Please add some more comments; I think this is when a packet comes in
> >>>on the primary, and then we find we've already got a packet from the secondary
> >>>waiting?
> >>yes,you are right
> >>
> >>I will add more comments in next version
> >Thank you.
> >
> >Dave
> >
> >>>>+            tmppkt = g_queue_pop_head(&connection->secondary_list);
> >>>>+            DEBUG("g_queue_get_length(&connection->primary_list)=%d\n",
> >>>>+                        g_queue_get_length(&connection->primary_list));
> >>>>+            DEBUG("g_queue_get_length(&connection->secondary_list)=%d\n",
> >>>>+                        g_queue_get_length(&connection->secondary_list));
> >>>>+            if (colo_packet_compare(pkt, tmppkt)) {
> >>>>+                DEBUG("packet same and release packet\n");
> >>>>+                pkt->should_be_sent = true;
> >>>>+                break;
> >>>>+            } else {
> >>>>+                DEBUG("packet different\n");
> >>>>+                colo_proxy_notify_checkpoint();
> >>>>+                pkt->should_be_sent = false;
> >>>>+                break;
> >>>>+            }
> >>>>+        } else {
> >>>>+            g_queue_push_tail(&connection->primary_list, pkt);
> >>>>+            pkt->should_be_sent = false;
> >>>>+        }
> >>>>+
> >>>>+        break;
> >>>>+    case SECONDARY_OUTPUT:
> >>>>+        g_queue_push_tail(&connection->secondary_list, pkt);
> >>>>+        DEBUG("secondary pkt data=%s,  pkt->ip->ipsrc=%x,pkt->ip->ipdst=%x\n",
> >>>>+                    (char *)pkt->data, pkt->ip->ip_src, pkt->ip->ip_dst);
> >>>>+        break;
> >>>>+    default:
> >>>>+        abort();
> >>>>+    }
> >>>>+
> >>>>+    return connection;
> >>>>+}
> >>>>+
> >>>>  /*
> >>>>   * Packets to be sent by colo forward to
> >>>>@@ -165,7 +329,8 @@ static ssize_t colo_proxy_primary_handler(NetFilterState *nf,
> >>>>      }
> >>>>      if (direction == NET_FILTER_DIRECTION_RX) {
> >>>>-        /* TODO: enqueue_primary_packet */
> >>>>+        ret = colo_enqueue_primary_packet(nf, sender, flags, iov,
> >>>>+                    iovcnt, sent_cb);
> >>>The routine above is 'colo_enqueue_packet' rather than colo_enqueue_primary_packet?
> >>yes,colo_enqueue_packet is enqueue packet common
> >>
> >>Thanks for review
> >>zhangchen
> >>
> >>>>      } else {
> >>>>          ret = colo_forward2another(nf, sender, flags, iov, iovcnt,
> >>>>                      sent_cb, COLO_PRIMARY_MODE);
> >>>>-- 
> >>>>1.9.1
> >>>Dave
> >>>
> >>>>
> >>>--
> >>>Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
> >>>
> >>>
> >>>.
> >>>
> >>
> >>
> >--
> >Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK
> >
> >
> >.
> >
> 
> 
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK