/* A network device (e.g. an Ethernet device).
*
- * Network device implementations should treat this structure as opaque. */
+ * Network device implementations may read these members but should not modify
+ * them. */
struct netdev {
char *name; /* Name of network device. */
const struct netdev_class *netdev_class; /* Functions to control
struct list saved_flags_list; /* Contains "struct netdev_saved_flags". */
};
-void netdev_init(struct netdev *, const char *name,
- const struct netdev_class *);
-void netdev_uninit(struct netdev *, bool destroy);
const char *netdev_get_type(const struct netdev *);
const struct netdev_class *netdev_get_class(const struct netdev *);
const char *netdev_get_name(const struct netdev *);
void netdev_get_devices(const struct netdev_class *,
struct shash *device_list);
+/* A data structure for capturing packets received by a network device.
+ *
+ * Network device implementations may read these members but should not modify
+ * them.
+ *
+ * None of these members change during the lifetime of a struct netdev_rx. */
+struct netdev_rx {
+ struct netdev *netdev; /* Owns a reference to the netdev. */
+};
+
+struct netdev *netdev_rx_get_netdev(const struct netdev_rx *);
+
/* Network device class structure, to be defined by each implementation of a
* network device.
*
* These functions return 0 if successful or a positive errno value on failure,
- * except where otherwise noted. */
+ * except where otherwise noted.
+ *
+ *
+ * Data Structures
+ * ===============
+ *
+ * These functions work primarily with two different kinds of data structures:
+ *
+ * - "struct netdev", which represents a network device.
+ *
+ * - "struct netdev_rx", which represents a handle for capturing packets
+ * received on a network device
+ *
+ * Each of these data structures contains all of the implementation-independent
+ * generic state for the respective concept, called the "base" state. None of
+ * them contains any extra space for implementations to use. Instead, each
+ * implementation is expected to declare its own data structure that contains
+ * an instance of the generic data structure plus additional
+ * implementation-specific members, called the "derived" state. The
+ * implementation can use casts or (preferably) the CONTAINER_OF macro to
+ * obtain access to derived state given only a pointer to the embedded generic
+ * data structure.
+ *
+ *
+ * Life Cycle
+ * ==========
+ *
+ * Four stylized functions accompany each of these data structures:
+ *
+ * "alloc" "construct" "destruct" "dealloc"
+ * ------------ ---------------- --------------- --------------
+ * netdev ->alloc ->construct ->destruct ->dealloc
+ * netdev_rx ->rx_alloc ->rx_construct ->rx_destruct ->rx_dealloc
+ *
+ * Any instance of a given data structure goes through the following life
+ * cycle:
+ *
+ * 1. The client calls the "alloc" function to obtain raw memory. If "alloc"
+ * fails, skip all the other steps.
+ *
+ * 2. The client initializes all of the data structure's base state. If this
+ * fails, skip to step 7.
+ *
+ * 3. The client calls the "construct" function. The implementation
+ * initializes derived state. It may refer to the already-initialized
+ * base state. If "construct" fails, skip to step 6.
+ *
+ * 4. The data structure is now initialized and in use.
+ *
+ * 5. When the data structure is no longer needed, the client calls the
+ * "destruct" function. The implementation uninitializes derived state.
+ * The base state has not been uninitialized yet, so the implementation
+ * may still refer to it.
+ *
+ * 6. The client uninitializes all of the data structure's base state.
+ *
+ * 7. The client calls the "dealloc" to free the raw memory. The
+ * implementation must not refer to base or derived state in the data
+ * structure, because it has already been uninitialized.
+ *
+ * Each "alloc" function allocates and returns a new instance of the respective
+ * data structure. The "alloc" function is not given any information about the
+ * use of the new data structure, so it cannot perform much initialization.
+ * Its purpose is just to ensure that the new data structure has enough room
+ * for base and derived state. It may return a null pointer if memory is not
+ * available, in which case none of the other functions is called.
+ *
+ * Each "construct" function initializes derived state in its respective data
+ * structure. When "construct" is called, all of the base state has already
+ * been initialized, so the "construct" function may refer to it. The
+ * "construct" function is allowed to fail, in which case the client calls the
+ * "dealloc" function (but not the "destruct" function).
+ *
+ * Each "destruct" function uninitializes and frees derived state in its
+ * respective data structure. When "destruct" is called, the base state has
+ * not yet been uninitialized, so the "destruct" function may refer to it. The
+ * "destruct" function is not allowed to fail.
+ *
+ * Each "dealloc" function frees raw memory that was allocated by the the
+ * "alloc" function. The memory's base and derived members might not have ever
+ * been initialized (but if "construct" returned successfully, then it has been
+ * "destruct"ed already). The "dealloc" function is not allowed to fail. */
struct netdev_class {
/* Type of netdevs in this class, e.g. "system", "tap", "gre", etc.
*
* the system. */
const char *type;
+/* ## ------------------- ## */
+/* ## Top-Level Functions ## */
+/* ## ------------------- ## */
+
/* Called when the netdev provider is registered, typically at program
* startup. Returning an error from this function will prevent any network
* device in this class from being opened.
* needed here. */
void (*wait)(void);
- /* Attempts to create a network device named 'name' in 'netdev_class'. On
- * success sets 'netdevp' to the newly created device. */
- int (*create)(const struct netdev_class *netdev_class, const char *name,
- struct netdev **netdevp);
+/* ## ---------------- ## */
+/* ## netdev Functions ## */
+/* ## ---------------- ## */
- /* Destroys 'netdev'.
- *
- * Netdev devices maintain a reference count that is incremented on
- * netdev_open() and decremented on netdev_close(). If 'netdev'
- * has a non-zero reference count, then this function will not be
- * called. */
- void (*destroy)(struct netdev *netdev);
+ /* Life-cycle functions for a netdev. See the large comment above on
+ * struct netdev_class. */
+ struct netdev *(*alloc)(void);
+ int (*construct)(struct netdev *);
+ void (*destruct)(struct netdev *);
+ void (*dealloc)(struct netdev *);
/* Fetches the device 'netdev''s configuration, storing it in 'args'.
* The caller owns 'args' and pre-initializes it to an empty smap.
const struct netdev_tunnel_config *
(*get_tunnel_config)(const struct netdev *netdev);
- /* Attempts to open a netdev_rx for receiving packets from 'netdev'.
- * Returns 0 if successful, otherwise a positive errno value. Returns
- * EOPNOTSUPP to indicate that the network device does not implement packet
- * reception through this interface. This function may be set to null if
- * it would always return EOPNOTSUPP anyhow. (This will prevent the
- * network device from being usefully used by the netdev-based "userspace
- * datapath".)
- *
- * On success, the implementation must set '*rxp' to a 'netdev_rx' for
- * 'netdev' that it has already initialized (with netdev_rx_init()). */
- int (*rx_open)(struct netdev *netdev, struct netdev_rx **rxp);
-
/* Sends the 'size'-byte packet in 'buffer' on 'netdev'. Returns 0 if
* successful, otherwise a positive errno value. Returns EAGAIN without
* blocking if the packet cannot be queued immediately. Returns EMSGSIZE
* returned sequence number is allowed to change even when 'netdev' doesn't
* change, although implementations should try to avoid this. */
unsigned int (*change_seq)(const struct netdev *netdev);
-};
-\f
-/* A data structure for capturing packets received by a network device.
- *
- * This structure should be treated as opaque by network device
- * implementations. */
-struct netdev_rx {
- const struct netdev_rx_class *rx_class;
- struct netdev *netdev;
-};
-void netdev_rx_init(struct netdev_rx *, struct netdev *,
- const struct netdev_rx_class *);
-void netdev_rx_uninit(struct netdev_rx *);
-struct netdev *netdev_rx_get_netdev(const struct netdev_rx *);
+/* ## ------------------- ## */
+/* ## netdev_rx Functions ## */
+/* ## ------------------- ## */
+
+/* If a particular netdev class does not support receiving packets, all these
+ * function pointers must be NULL. */
-struct netdev_rx_class {
- /* Destroys 'rx'. */
- void (*destroy)(struct netdev_rx *rx);
+ /* Life-cycle functions for a netdev_rx. See the large comment above on
+ * struct netdev_class. */
+ struct netdev_rx *(*rx_alloc)(void);
+ int (*rx_construct)(struct netdev_rx *);
+ void (*rx_destruct)(struct netdev_rx *);
+ void (*rx_dealloc)(struct netdev_rx *);
/* Attempts to receive a packet from 'rx' into the 'size' bytes in
* 'buffer'. If successful, returns the number of bytes in the received
* if no packet is ready to be received.
*
* Must return -EMSGSIZE, and discard the packet, if the received packet
- * is longer than 'size' bytes. */
- int (*recv)(struct netdev_rx *rx, void *buffer, size_t size);
+ * is longer than 'size' bytes.
+ *
+ * Specify NULL if this */
+ int (*rx_recv)(struct netdev_rx *rx, void *buffer, size_t size);
/* Registers with the poll loop to wake up from the next call to
* poll_block() when a packet is ready to be received with netdev_rx_recv()
* on 'rx'. */
- void (*wait)(struct netdev_rx *rx);
+ void (*rx_wait)(struct netdev_rx *rx);
/* Discards all packets waiting to be received from 'rx'. */
- int (*drain)(struct netdev_rx *rx);
+ int (*rx_drain)(struct netdev_rx *rx);
};
-static inline void netdev_rx_assert_class(const struct netdev_rx *rx,
- const struct netdev_rx_class *class_)
-{
- ovs_assert(rx->rx_class == class_);
-}
-
int netdev_register_provider(const struct netdev_class *);
int netdev_unregister_provider(const char *type);
const struct netdev_class *netdev_lookup_provider(const char *type);
git://git.onelab.eu / sliver-openvswitch.git / blobdiff