X-Git-Url: http://git.onelab.eu/?a=blobdiff_plain;f=lib%2Fnetdev-provider.h;h=23905d41366c718c69343f748716a28e2b3f3c31;hb=fa04edcedfe5285fd8ad3a4d70fecb38df18293d;hp=9af0398cff66d9c414e2c648139bcb9bd7ea7b1d;hpb=a12945b3b8cd4d483e5e8f2a1adb6576badf1d4d;p=sliver-openvswitch.git diff --git a/lib/netdev-provider.h b/lib/netdev-provider.h index 9af0398cf..23905d413 100644 --- a/lib/netdev-provider.h +++ b/lib/netdev-provider.h @@ -30,19 +30,20 @@ extern "C" { /* 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 { + /* The following do not change during the lifetime of a struct netdev. */ char *name; /* Name of network device. */ const struct netdev_class *netdev_class; /* Functions to control this device. */ + + /* The following are protected by 'netdev_mutex' (internal to netdev.c). */ int ref_cnt; /* Times this devices was opened. */ struct shash_node *node; /* Pointer to element in global map. */ 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 *); @@ -50,17 +51,104 @@ struct netdev *netdev_from_name(const char *name); void netdev_get_devices(const struct netdev_class *, struct shash *device_list); -static inline void netdev_assert_class(const struct netdev *netdev, - const struct netdev_class *class_) -{ - ovs_assert(netdev->netdev_class == class_); -} +/* 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. * @@ -70,6 +158,10 @@ struct netdev_class { * 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. @@ -89,18 +181,16 @@ struct netdev_class { * 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. @@ -122,18 +212,6 @@ struct netdev_class { 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 @@ -524,25 +602,20 @@ struct netdev_class { * 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); -}; - -/* 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 @@ -550,27 +623,22 @@ struct netdev_rx_class { * 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); extern const struct netdev_class netdev_linux_class; extern const struct netdev_class netdev_internal_class;