On 6/20/19 8:03 AM, Jack Wang wrote:
From: Roman Pen <roman.penyaev@xxxxxxxxxxxxxxxx>
Introduce public header which provides set of API functions to
establish RDMA connections from client to server machine using
IBTRS protocol, which manages RDMA connections for each session,
does multipathing and load balancing.
Main functions for client (active) side:
ibtrs_clt_open() - Creates set of RDMA connections incapsulated
^^^ ^^^^^^^^^^^^
a? encapsulated?
in IBTRS session and returns pointer on IBTRS
^^^ ^^^ ^^
a? a? to an?
session object.
[ ... ]
+/**
+ * enum ibtrs_clt_link_ev - Events about connectivity state of a client
+ * @IBTRS_CLT_LINK_EV_RECONNECTED Client was reconnected.
+ * @IBTRS_CLT_LINK_EV_DISCONNECTED Client was disconnected.
+ */
+enum ibtrs_clt_link_ev {
+ IBTRS_CLT_LINK_EV_RECONNECTED,
+ IBTRS_CLT_LINK_EV_DISCONNECTED,
+};
+
+/**
+ * Source and destination address of a path to be established
+ */
+struct ibtrs_addr {
+ struct sockaddr_storage *src;
+ struct sockaddr_storage *dst;
+};
Is it really useful to define a structure to hold two pointers or can
these two pointers also be passed as separate arguments?
+/**
+ * ibtrs_clt_open() - Open a session to a IBTRS client
+ * @priv: User supplied private data.
+ * @link_ev: Event notification for connection state changes
+ * @priv: user supplied data that was passed to
+ * ibtrs_clt_open()
+ * @ev: Occurred event
+ * @sessname: name of the session
+ * @paths: Paths to be established defined by their src and dst addresses
+ * @path_cnt: Number of elemnts in the @paths array
+ * @port: port to be used by the IBTRS session
+ * @pdu_sz: Size of extra payload which can be accessed after tag allocation.
+ * @max_inflight_msg: Max. number of parallel inflight messages for the session
+ * @max_segments: Max. number of segments per IO request
+ * @reconnect_delay_sec: time between reconnect tries
+ * @max_reconnect_attempts: Number of times to reconnect on error before giving
+ * up, 0 for * disabled, -1 for forever
+ *
+ * Starts session establishment with the ibtrs_server. The function can block
+ * up to ~2000ms until it returns.
+ *
+ * Return a valid pointer on success otherwise PTR_ERR.
+ */
+struct ibtrs_clt *ibtrs_clt_open(void *priv, link_clt_ev_fn *link_ev,
+ const char *sessname,
+ const struct ibtrs_addr *paths,
+ size_t path_cnt, short port,
+ size_t pdu_sz, u8 reconnect_delay_sec,
+ u16 max_segments,
+ s16 max_reconnect_attempts);
Having detailed kernel-doc headers for describing API functions is great
but I'm not sure a .h file is the best location for such documentation.
Many kernel developers keep kernel-doc headers in .c files because that
makes it more likely that the documentation and the implementation stay
in sync.
+
+/**
+ * ibtrs_clt_close() - Close a session
+ * @sess: Session handler, is freed on return
^^^^^^^
handle?
This sentence suggests that the handle is freed on return. I guess that
you meant that the session is freed upon return?
+/**
+ * ibtrs_clt_get_tag() - allocates tag for future RDMA operation
+ * @sess: Current session
+ * @con_type: Type of connection to use with the tag
+ * @wait: Wait type
+ *
+ * Description:
+ * Allocates tag for the following RDMA operation. Tag is used
+ * to preallocate all resources and to propagate memory pressure
+ * up earlier.
+ *
+ * Context:
+ * Can sleep if @wait == IBTRS_TAG_WAIT
+ */
+struct ibtrs_tag *ibtrs_clt_get_tag(struct ibtrs_clt *sess,
+ enum ibtrs_clt_con_type con_type,
+ int wait);
Since struct ibtrs_tag has another role than what is called a tag in the
block layer I think a better description is needed of what struct
ibtrs_tag actually represents.
+/*
+ * Here goes IBTRS server API
+ */
Most software either uses the client API or the server API but not both
at the same time. Has it been considered to use separate header files
for the client and server APIs?
Bart.
