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Annotation of OSKit-Mach/oskit/ds_request.h, revision 1.1

1.1     ! root        1: #ifndef        _DS_REQUEST_H_
        !             2: #define        _DS_REQUEST_H_
        !             3: 
        !             4: #include "ds_oskit.h"
        !             5: #include <kern/zalloc.h>
        !             6: #include <kern/queue.h>
        !             7: #include <kern/lock.h>
        !             8: 
        !             9: /* This structure describes a pending asynchronous device request.
        !            10: 
        !            11:    That is, an i/o that is in progress but with no thread waiting for it.
        !            12:    We store here all the information we need to complete the i/o and send
        !            13:    the reply message to complete the device RPC.
        !            14: 
        !            15:    This is currently only used for oskit asyncio devices, but can be
        !            16:    extended for other types e.g. when the oskit gives us a way not to
        !            17:    block the device request thread doing disk i/o.
        !            18: 
        !            19:    These structures are queued on the device's read_queue or write_queue.
        !            20:    Notifications from the device put the device itself onto the
        !            21:    device_ready_queue and wake the io_done_thread.  The io_done_thread
        !            22:    takes devices off the ready queue, polls them for i/o availability
        !            23:    and then dequeues requests from their read_queue and/or write_queue
        !            24:    as long as there is i/o available.
        !            25: 
        !            26:    All of these queues are accessed at splio and locked by
        !            27:    device_ready_queue_lock.  */
        !            28: 
        !            29: struct pending_request {
        !            30:   queue_chain_t chain;         /* on device's read_queue or write_queue */
        !            31: 
        !            32:   void (*completer) (device_t, struct pending_request *);
        !            33: 
        !            34:   struct ipc_port *reply_port;
        !            35:   mach_msg_type_name_t reply_port_type;
        !            36: 
        !            37:   oskit_size_t count, offset;
        !            38: 
        !            39:   union device_data {
        !            40:     vm_map_copy_t outofband;
        !            41:     char *inband;              /* from io_inband_zone */
        !            42:     vm_offset_t inbando;       /* rather than casting */
        !            43: #define IO_SMALL_MAX   (sizeof (vm_map_copy_t))
        !            44:     char small[IO_SMALL_MAX];
        !            45:   } data;
        !            46: };
        !            47: 
        !            48: extern zone_t io_req_zone;
        !            49: #define request_allocate()     ((void *) zalloc (io_req_zone))
        !            50: #define request_free(req)      (zfree (io_req_zone, (vm_offset_t) (req)))
        !            51: 
        !            52: 
        !            53: extern queue_head_t device_ready_queue;
        !            54: decl_simple_lock_data(extern, device_ready_queue_lock)
        !            55: 
        !            56: extern void ds_request_init (void);
        !            57: extern void ds_device_ready (device_t);
        !            58: extern void ds_asyncio_ready (device_t);
        !            59: 
        !            60: 
        !            61: 
        !            62: #endif

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