4 * Implements LWKT messages and ports.
6 * $DragonFly: src/sys/sys/msgport.h,v 1.20 2004/09/10 18:23:54 dillon Exp $
9 #ifndef _SYS_MSGPORT_H_
10 #define _SYS_MSGPORT_H_
13 #include <sys/queue.h> /* TAILQ_* macros */
15 #ifndef _SYS_STDINT_H_
16 #include <sys/stdint.h>
23 typedef struct lwkt_msg *lwkt_msg_t;
24 typedef struct lwkt_port *lwkt_port_t;
26 typedef TAILQ_HEAD(lwkt_msg_queue, lwkt_msg) lwkt_msg_queue;
29 * LWKT command message operator type. This type holds a message's
30 * 'command'. The command format is opaque to the LWKT messaging system,
31 * meaning that it is specific to whatever convention the API chooses.
32 * By convention lwkt_cmd_t is passed by value and is expected to
33 * efficiently fit into a machine register.
35 typedef union lwkt_cmd {
37 int (*cm_func)(lwkt_msg_t msg);
41 * The standard message and port structure for communications between
42 * threads. See kern/lwkt_msgport.c for documentation on how messages and
45 * For the most part a message may only be manipulated by whomever currently
46 * owns it, which generally means the originating port if the message has
47 * not been sent yet or has been replied, and the target port if the message
48 * has been sent and/or is undergoing processing.
50 * The one exception to this rule is an abort. Aborts must be initiated
51 * by the originator and may 'chase' the target (especially if a message
52 * is being forwarded), potentially even 'chase' the message all the way
53 * back to the originator if it races against the target replying the
54 * message. The ms_abort_port field is the only field that may be modified
55 * by the originator or intermediate target (when the abort is chasing
56 * a forwarding or reply op). An abort may cause a reply to be delayed
57 * until the abort catches up to it.
59 * Messages which support an abort will have MSGF_ABORTABLE set, indicating
60 * that the ms_abort field has been initialized. An abort will cause a
61 * message to be requeued to the target port so the target sees the same
62 * message twice: once during initial processing of the message, and a
63 * second time to process the abort request. lwkt_getport() will detect
64 * the requeued abort and will copy ms_abort into ms_cmd before returning
65 * the requeued message the second time. This makes target processing a
66 * whole lot less complex.
68 * NOTE! 64-bit-align this structure.
70 typedef struct lwkt_msg {
71 TAILQ_ENTRY(lwkt_msg) ms_node; /* link node (see note above) */
73 struct lwkt_msg *ms_next; /* chaining / cache */
74 union sysunion *ms_sysunnext; /* chaining / cache */
75 struct lwkt_msg *ms_umsg; /* user message (UVA address) */
77 lwkt_port_t ms_target_port; /* current target or relay port */
78 lwkt_port_t ms_reply_port; /* async replies returned here */
79 lwkt_port_t ms_abort_port; /* abort chasing port */
80 lwkt_cmd_t ms_cmd; /* message command operator */
81 lwkt_cmd_t ms_abort; /* message abort operator */
82 int ms_flags; /* message flags */
83 #define ms_copyout_start ms_msgsize
84 int ms_msgsize; /* size of message */
85 int ms_error; /* positive error code or 0 */
87 void *ms_resultp; /* misc pointer data or result */
88 int ms_result; /* standard 'int'eger result */
89 long ms_lresult; /* long result */
90 int ms_fds[2]; /* two int bit results */
91 __int32_t ms_result32; /* 32 bit result */
92 __int64_t ms_result64; /* 64 bit result */
93 __off_t ms_offset; /* off_t result */
95 #define ms_copyout_end ms_pad[0]
96 int ms_pad[2]; /* future use */
99 #define ms_copyout_size (offsetof(struct lwkt_msg, ms_copyout_end) - offsetof(struct lwkt_msg, ms_copyout_start))
101 #define MSGF_DONE 0x0001 /* asynch message is complete */
102 #define MSGF_REPLY1 0x0002 /* asynch message has been returned */
103 #define MSGF_QUEUED 0x0004 /* message has been queued sanitychk */
104 #define MSGF_ASYNC 0x0008 /* sync/async hint */
105 #define MSGF_ABORTED 0x0010 /* indicate pending abort */
106 #define MSGF_PCATCH 0x0020 /* catch proc signal while waiting */
107 #define MSGF_REPLY2 0x0040 /* reply processed by rport cpu */
108 #define MSGF_ABORTABLE 0x0080 /* message supports abort */
109 #define MSGF_RETRIEVED 0x0100 /* message retrieved on target */
111 #define MSG_CMD_CDEV 0x00010000
112 #define MSG_CMD_VFS 0x00020000
113 #define MSG_CMD_SYSCALL 0x00030000
114 #define MSG_SUBCMD_MASK 0x0000FFFF
117 #ifdef MALLOC_DECLARE
118 MALLOC_DECLARE(M_LWKTMSG);
123 * Notes on port processing requirements:
126 * - may return synchronous error code (error != EASYNC) directly and
127 * does not need to check or set MSGF_DONE if so, or set ms_target_port
128 * - for asynch procesing should clear MSGF_DONE and set ms_target_port
129 * to port prior to initiation of the command.
132 * - if the passed msg is NULL we wait for, remove, and return the
133 * next pending message on the port.
134 * - if the passed msg is non-NULL we wait for that particular message,
135 * which typically involves waiting until MSGF_DONE is set then
136 * pulling the message off the port if MSGF_QUEUED is set and
137 * returning it. If MSGF_PCATCH is set in the message we allow
138 * a signal to interrupt and abort the message.
141 * - reply a message (executed on the originating port to return a
142 * message to it). This can be rather involved if abort is to be
143 * supported, see lwkt_default_replyport(). Generally speaking
144 * one sets MSGF_DONE. If MSGF_ASYNC is set the message is queued
145 * to the port, else the port's thread is scheduled.
148 * - abort a message. The mp_abortport function for the message's
149 * ms_target_port is called. ms_target_port is basically where
150 * the message was sent to or last forwarded to. Aborting a message
151 * can be rather involved. Note that the lwkt_getmsg() code ensures
152 * that a message is returned non-abort before it is returned again
153 * with its ms_cmd set to ms_abort, even if the abort occurs before
154 * the initial retrieval of the message. The setting of ms_cmd to
155 * ms_abort is NOT handled by mp_abortport(). mp_abortport() is
156 * basically responsible for requeueing the message to the target
157 * port and setting the MSGF_ABORTED flag.
160 typedef struct lwkt_port {
161 lwkt_msg_queue mp_msgq;
164 struct thread *mp_td;
165 int (*mp_putport)(lwkt_port_t, lwkt_msg_t);
166 void * (*mp_waitport)(lwkt_port_t, lwkt_msg_t);
167 void (*mp_replyport)(lwkt_port_t, lwkt_msg_t);
168 void (*mp_abortport)(lwkt_port_t, lwkt_msg_t);
171 #define MSGPORTF_WAITING 0x0001
174 * These functions are good for userland as well as the kernel. The
175 * messaging function support for userland is provided by the kernel's
176 * kern/lwkt_msgport.c. The port functions are provided by userland.
178 void lwkt_initport(lwkt_port_t, struct thread *);
179 void lwkt_initport_null_rport(lwkt_port_t, struct thread *);
180 void lwkt_sendmsg(lwkt_port_t, lwkt_msg_t);
181 int lwkt_domsg(lwkt_port_t, lwkt_msg_t);
182 int lwkt_forwardmsg(lwkt_port_t, lwkt_msg_t);
183 void lwkt_abortmsg(lwkt_msg_t);
184 void *lwkt_getport(lwkt_port_t);
186 int lwkt_default_putport(lwkt_port_t port, lwkt_msg_t msg);
187 void *lwkt_default_waitport(lwkt_port_t port, lwkt_msg_t msg);
188 void lwkt_default_replyport(lwkt_port_t port, lwkt_msg_t msg);
189 void lwkt_default_abortport(lwkt_port_t port, lwkt_msg_t msg);
190 void lwkt_null_replyport(lwkt_port_t port, lwkt_msg_t msg);