forked from luck/tmp_suning_uos_patched
92ce034b5a
There are essentially two types of ceph messages: incoming and outgoing. Outgoing messages are always allocated via ceph_msg_new(), and at the time of their allocation they are not associated with any particular connection. Incoming messages are always allocated via ceph_con_in_msg_alloc(), and they are initially associated with the connection from which incoming data will be placed into the message. When an outgoing message gets sent, it becomes associated with a connection and remains that way until the message is successfully sent. The association of an incoming message goes away at the point it is sent to an upper layer via a con->ops->dispatch method. This patch implements reference counting for all ceph messages, such that every message holds a reference (and a pointer) to a connection if and only if it is associated with that connection (as described above). For background, here is an explanation of the ceph message lifecycle, emphasizing when an association exists between a message and a connection. Outgoing Messages An outgoing message is "owned" by its allocator, from the time it is allocated in ceph_msg_new() up to the point it gets queued for sending in ceph_con_send(). Prior to that point the message's msg->con pointer is null; at the point it is queued for sending its message pointer is assigned to refer to the connection. At that time the message is inserted into a connection's out_queue list. When a message on the out_queue list has been sent to the socket layer to be put on the wire, it is transferred out of that list and into the connection's out_sent list. At that point it is still owned by the connection, and will remain so until an acknowledgement is received from the recipient that indicates the message was successfully transferred. When such an acknowledgement is received (in process_ack()), the message is removed from its list (in ceph_msg_remove()), at which point it is no longer associated with the connection. So basically, any time a message is on one of a connection's lists, it is associated with that connection. Reference counting outgoing messages can thus be done at the points a message is added to the out_queue (in ceph_con_send()) and the point it is removed from either its two lists (in ceph_msg_remove())--at which point its connection pointer becomes null. Incoming Messages When an incoming message on a connection is getting read (in read_partial_message()) and there is no message in con->in_msg, a new one is allocated using ceph_con_in_msg_alloc(). At that point the message is associated with the connection. Once that message has been completely and successfully read, it is passed to upper layer code using the connection's con->ops->dispatch method. At that point the association between the message and the connection no longer exists. Reference counting of connections for incoming messages can be done by taking a reference to the connection when the message gets allocated, and releasing that reference when it gets handed off using the dispatch method. We should never fail to get a connection reference for a message--the since the caller should already hold one. Signed-off-by: Alex Elder <elder@inktank.com> Reviewed-by: Sage Weil <sage@inktank.com> |
||
|---|---|---|
| .. | ||
| 9p | ||
| 802 | ||
| 8021q | ||
| appletalk | ||
| atm | ||
| ax25 | ||
| batman-adv | ||
| bluetooth | ||
| bridge | ||
| caif | ||
| can | ||
| ceph | ||
| core | ||
| dcb | ||
| dccp | ||
| decnet | ||
| dns_resolver | ||
| dsa | ||
| econet | ||
| ethernet | ||
| ieee802154 | ||
| ipv4 | ||
| ipv6 | ||
| ipx | ||
| irda | ||
| iucv | ||
| key | ||
| l2tp | ||
| lapb | ||
| llc | ||
| mac80211 | ||
| netfilter | ||
| netlabel | ||
| netlink | ||
| netrom | ||
| nfc | ||
| openvswitch | ||
| packet | ||
| phonet | ||
| rds | ||
| rfkill | ||
| rose | ||
| rxrpc | ||
| sched | ||
| sctp | ||
| sunrpc | ||
| tipc | ||
| unix | ||
| wanrouter | ||
| wimax | ||
| wireless | ||
| x25 | ||
| xfrm | ||
| compat.c | ||
| Kconfig | ||
| Makefile | ||
| nonet.c | ||
| socket.c | ||
| sysctl_net.c | ||