2 * Copyright (c) 2003 Matthew Dillon <dillon@backplane.com>
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
8 * 1. Redistributions of source code must retain the above copyright
9 * notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 * notice, this list of conditions and the following disclaimer in the
12 * documentation and/or other materials provided with the distribution.
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * NOTE! This file may be compiled for userland libraries as well as for
29 * $DragonFly: src/sys/kern/lwkt_msgport.c,v 1.20 2004/04/20 01:52:22 dillon Exp $
34 #include <sys/param.h>
35 #include <sys/systm.h>
36 #include <sys/kernel.h>
38 #include <sys/rtprio.h>
39 #include <sys/queue.h>
40 #include <sys/sysctl.h>
41 #include <sys/kthread.h>
42 #include <sys/signalvar.h>
43 #include <machine/cpu.h>
47 #include <vm/vm_param.h>
48 #include <vm/vm_kern.h>
49 #include <vm/vm_object.h>
50 #include <vm/vm_page.h>
51 #include <vm/vm_map.h>
52 #include <vm/vm_pager.h>
53 #include <vm/vm_extern.h>
54 #include <vm/vm_zone.h>
56 #include <sys/thread2.h>
57 #include <sys/msgport2.h>
59 #include <machine/stdarg.h>
60 #include <machine/ipl.h>
61 #include <machine/cpufunc.h>
63 #include <machine/smp.h>
66 #include <sys/malloc.h>
67 MALLOC_DEFINE(M_LWKTMSG, "lwkt message", "lwkt message");
71 #include <sys/stdint.h>
72 #include <libcaps/thread.h>
73 #include <sys/thread.h>
74 #include <sys/msgport.h>
75 #include <sys/errno.h>
76 #include <libcaps/globaldata.h>
77 #include <sys/thread2.h>
78 #include <sys/msgport2.h>
84 /************************************************************************
86 ************************************************************************/
88 static void lwkt_replyport_remote(lwkt_msg_t msg);
89 static void lwkt_putport_remote(lwkt_msg_t msg);
94 * Send a message asynchronously. This function requests asynchronous
95 * completion and calls lwkt_beginmsg(). If the target port decides to
96 * run the message synchronously this function will automatically queue
97 * the message to the current thread's message queue to present a
98 * consistent interface to the caller.
100 * The message's ms_cmd must be initialized and its ms_flags must
101 * be zero'd out. lwkt_sendmsg() will initialize the ms_abort_port
102 * (abort chasing port). If abort is supported, ms_abort must also be
105 * NOTE: you cannot safely request an abort until lwkt_sendmsg() returns
109 lwkt_sendmsg(lwkt_port_t port, lwkt_msg_t msg)
113 msg->ms_flags |= MSGF_ASYNC;
114 msg->ms_flags &= ~(MSGF_REPLY1 | MSGF_REPLY2 | MSGF_QUEUED | \
115 MSGF_ABORTED | MSGF_RETRIEVED);
116 KKASSERT(msg->ms_reply_port != NULL);
117 msg->ms_abort_port = msg->ms_reply_port;
118 if ((error = lwkt_beginmsg(port, msg)) != EASYNC) {
119 lwkt_replymsg(msg, error);
126 * Send a message synchronously. This function requests synchronous
127 * completion and calls lwkt_beginmsg(). If the target port decides to
128 * run the message asynchronously this function will block waiting for
129 * the message to complete. Since MSGF_ASYNC is not set the target
130 * will not attempt to queue the reply to a reply port but will simply
131 * wake up anyone waiting on the message.
133 * A synchronous error code is always returned.
135 * The message's ms_cmd must be initialized, and its ms_flags must be
136 * at least zero'd out. lwkt_domsg() will initialize the message's
137 * ms_abort_port (abort chasing port). If abort is supported, ms_abort
138 * must also be initialized.
140 * NOTE: you cannot safely request an abort until lwkt_domsg() blocks.
141 * XXX this probably needs some work.
144 lwkt_domsg(lwkt_port_t port, lwkt_msg_t msg)
148 msg->ms_flags &= ~(MSGF_ASYNC | MSGF_REPLY1 | MSGF_REPLY2 | \
149 MSGF_QUEUED | MSGF_ABORTED | MSGF_RETRIEVED);
150 KKASSERT(msg->ms_reply_port != NULL);
151 msg->ms_abort_port = msg->ms_reply_port;
152 if ((error = lwkt_beginmsg(port, msg)) == EASYNC) {
153 error = lwkt_waitmsg(msg);
158 /************************************************************************
160 ************************************************************************/
165 * Initialize a port for use and assign it to the specified thread.
168 lwkt_initport(lwkt_port_t port, thread_t td)
170 bzero(port, sizeof(*port));
171 TAILQ_INIT(&port->mp_msgq);
173 port->mp_putport = lwkt_default_putport;
174 port->mp_waitport = lwkt_default_waitport;
175 port->mp_replyport = lwkt_default_replyport;
176 port->mp_abortport = lwkt_default_abortport;
182 * Retrieve the next message from the port's message queue, return NULL
183 * if no messages are pending. Note that callers CANNOT use the
184 * MSGF_ABORTED flag as a litmus test to determine if a message
185 * was aborted. The flag only indicates that an abort was requested.
186 * The message's error code will indicate whether an abort occured
187 * (typically by returning EINTR).
189 * Note that once a message has been dequeued it is subject to being
190 * requeued via an IPI based abort request if it is not marked MSGF_DONE.
192 * If the message has been aborted we have to guarentee that abort
193 * semantics are properly followed. The target port will always see
194 * the original message at least once, and if it does not reply the
195 * message before looping on its message port again it will then see
196 * the message again with ms_cmd set to ms_abort.
198 * The calling thread MUST own the port.
203 _lwkt_pullmsg(lwkt_port_t port, lwkt_msg_t msg)
205 if ((msg->ms_flags & MSGF_ABORTED) == 0) {
207 * normal case, remove and return the message.
209 TAILQ_REMOVE(&port->mp_msgq, msg, ms_node);
210 msg->ms_flags = (msg->ms_flags & ~MSGF_QUEUED) | MSGF_RETRIEVED;
212 if (msg->ms_flags & MSGF_RETRIEVED) {
214 * abort case, message already returned once, remvoe and
215 * return the aborted message a second time after setting
216 * ms_cmd to ms_abort.
218 TAILQ_REMOVE(&port->mp_msgq, msg, ms_node);
219 msg->ms_flags &= ~MSGF_QUEUED;
220 msg->ms_cmd = msg->ms_abort;
223 * abort case, abort races initial message retrieval. The
224 * message is returned normally but not removed from the
225 * queue. On the next loop the 'aborted' message will be
226 * dequeued and returned. Note that if the caller replies
227 * to the message it will be dequeued (the abort becomes a
230 msg->ms_flags |= MSGF_RETRIEVED;
236 lwkt_getport(lwkt_port_t port)
240 KKASSERT(port->mp_td == curthread);
242 crit_enter_quick(port->mp_td);
243 if ((msg = TAILQ_FIRST(&port->mp_msgq)) != NULL)
244 _lwkt_pullmsg(port, msg);
245 crit_exit_quick(port->mp_td);
250 * This inline helper function completes processing of a reply from an
251 * unknown cpu context.
253 * The message is being returned to the specified port. The port is
254 * owned by the mp_td thread. If we are on the same cpu as the mp_td
255 * thread we can trivially queue the message to the reply port and schedule
256 * the target thread, otherwise we have to send an ipi message to the
259 * This inline must be entered with a critical section already held.
260 * Note that the IPIQ callback function (*_remote) is entered with a
261 * critical section already held, and we obtain one in lwkt_replyport().
265 _lwkt_replyport(lwkt_port_t port, lwkt_msg_t msg, int force)
267 thread_t td = port->mp_td;
269 if (force || td->td_gd == mycpu) {
271 * We can only reply the message if the abort has caught up with us,
272 * or if no abort was issued (same case).
274 if (msg->ms_abort_port == port) {
275 KKASSERT((msg->ms_flags & MSGF_QUEUED) == 0);
276 TAILQ_INSERT_TAIL(&port->mp_msgq, msg, ms_node);
277 msg->ms_flags |= MSGF_DONE | MSGF_QUEUED | MSGF_REPLY2;
278 if (port->mp_flags & MSGPORTF_WAITING)
282 lwkt_send_ipiq(td->td_gd, (ipifunc_t)lwkt_replyport_remote, msg);
287 * This function completes reply processing for the default case in the
288 * context of the originating cpu.
292 lwkt_replyport_remote(lwkt_msg_t msg)
294 _lwkt_replyport(msg->ms_reply_port, msg, 1);
298 * This function is called in the context of the target to reply a message.
299 * Note that the lwkt_replymsg() inline has already set MSGF_REPLY1 and
300 * entered a critical section for us.
304 lwkt_default_replyport(lwkt_port_t port, lwkt_msg_t msg)
307 msg->ms_flags |= MSGF_REPLY1;
308 if (msg->ms_flags & MSGF_ASYNC) {
310 * An abort may have caught up to us while we were processing the
311 * message. If this occured we have to dequeue the message from the
312 * target port in the context of our current cpu before we can
313 * finish replying it.
315 * If an abort occurs after we reply the MSGF_REPLY1 flag will
316 * prevent it from being requeued to the target port.
318 if (msg->ms_flags & MSGF_QUEUED) {
319 KKASSERT(msg->ms_flags & MSGF_ABORTED);
320 TAILQ_REMOVE(&msg->ms_target_port->mp_msgq, msg, ms_node);
321 msg->ms_flags &= ~MSGF_QUEUED;
323 _lwkt_replyport(port, msg, 0);
326 * Synchronously executed messages cannot be aborted and are just
327 * marked done. YYY MSGF_DONE should already be set, change flag set
330 msg->ms_flags |= MSGF_DONE;
331 if (port->mp_flags & MSGPORTF_WAITING)
332 lwkt_schedule(port->mp_td);
338 * lwkt_default_putport()
340 * This function is typically assigned to the mp_putport port vector.
342 * Queue a message to the target port and wakeup the thread owning it.
343 * This function always returns EASYNC and may be assigned to a
344 * message port's mp_putport function vector. Note that we must set
345 * MSGF_QUEUED prior to sending any IPIs in order to interlock against
346 * ABORT requests and other tests that might be performed.
348 * The inline must be called from a critical section (the remote function
349 * is called from an IPI and will be in a critical section).
354 _lwkt_putport(lwkt_port_t port, lwkt_msg_t msg, int force)
356 thread_t td = port->mp_td;
358 if (force || td->td_gd == mycpu) {
359 TAILQ_INSERT_TAIL(&port->mp_msgq, msg, ms_node);
360 if (port->mp_flags & MSGPORTF_WAITING)
363 lwkt_send_ipiq(td->td_gd, (ipifunc_t)lwkt_putport_remote, msg);
369 lwkt_putport_remote(lwkt_msg_t msg)
371 _lwkt_putport(msg->ms_target_port, msg, 1);
375 lwkt_default_putport(lwkt_port_t port, lwkt_msg_t msg)
378 msg->ms_flags |= MSGF_QUEUED; /* abort interlock */
379 msg->ms_flags &= ~MSGF_DONE;
380 msg->ms_target_port = port;
381 _lwkt_putport(port, msg, 0);
389 * Forward a message received on one port to another port. The forwarding
390 * function must deal with a pending abort but othewise essentially just
391 * issues a putport to the target port.
393 * An abort may have two side effects: First, the message may have been
394 * requeued to the current target port. If so, we must dequeue it before
398 lwkt_forwardmsg(lwkt_port_t port, lwkt_msg_t msg)
403 if (msg->ms_flags & MSGF_QUEUED) {
404 KKASSERT(msg->ms_flags & MSGF_ABORTED);
405 TAILQ_REMOVE(&msg->ms_target_port->mp_msgq, msg, ms_node);
406 msg->ms_flags &= ~MSGF_QUEUED;
408 msg->ms_flags &= ~MSGF_RETRIEVED;
409 if ((error = port->mp_putport(port, msg)) != EASYNC)
410 lwkt_replymsg(msg, error);
418 * Aborting a message is a fairly complex task. The first order of
419 * business is to get the message to the cpu that owns the target
420 * port, during which we may have to do some port chasing due to
421 * message forwarding operations.
423 * NOTE! Since an aborted message is requeued all message processing
424 * loops should check the MSGF_ABORTED flag.
426 static void lwkt_abortmsg_remote(lwkt_msg_t msg);
429 lwkt_abortmsg(lwkt_msg_t msg)
435 * A critical section protects us from reply IPIs on this cpu. We
436 * can only abort messages that have not yet completed (DONE), are not
437 * in the midst of being replied (REPLY1), and which support the
438 * abort function (ABORTABLE).
441 if ((msg->ms_flags & (MSGF_DONE|MSGF_REPLY1|MSGF_ABORTABLE)) == MSGF_ABORTABLE) {
443 * Chase the message. If REPLY1 is set the message has been replied
444 * all the way back to the originator, otherwise it is sitting on
445 * ms_target_port (but we can only complete processing if we are
446 * on the same cpu as the selected port in order to avoid
447 * SMP cache synchronization issues).
449 * When chasing through multiple ports ms_flags may not be
450 * synchronized to the current cpu, but it WILL be synchronized
451 * with regards to testing the MSGF_REPLY1 bit once we reach the
452 * target port that made the reply and since the cpu owning
453 * some port X stores the new port in ms_target_port if the message
454 * is forwarded, the current port will only ever equal the target
455 * port when we are on the correct cpu.
457 if (msg->ms_flags & MSGF_REPLY1)
458 port = msg->ms_reply_port;
460 port = msg->ms_target_port;
463 if (td->td_gd != mycpu) {
464 lwkt_send_ipiq(td->td_gd, (ipifunc_t)lwkt_abortmsg_remote, msg);
466 port->mp_abortport(port, msg);
474 lwkt_abortmsg_remote(lwkt_msg_t msg)
479 if (msg->ms_flags & MSGF_REPLY1)
480 port = msg->ms_reply_port;
482 port = msg->ms_target_port;
485 if (td->td_gd != mycpu) {
486 lwkt_send_ipiq(td->td_gd, (ipifunc_t)lwkt_abortmsg_remote, msg);
488 port->mp_abortport(port, msg);
493 * The mp_abortport function is called when the abort has finally caught up
494 * to the target port or (if the message has been replied) the reply port.
497 lwkt_default_abortport(lwkt_port_t port, lwkt_msg_t msg)
500 * Set ms_abort_port to ms_reply_port to indicate the completion of
501 * the messaging chasing portion of the abort request. Note that
502 * the passed port is the port that we finally caught up to, not
503 * necessarily the reply port.
505 msg->ms_abort_port = msg->ms_reply_port;
507 if (msg->ms_flags & MSGF_REPLY2) {
509 * If REPLY2 is set we must have chased it all the way back to
510 * the reply port, but the replyport code has not queued the message
511 * (because it was waiting for the abort to catch up). We become
512 * responsible for queueing the message to the reply port.
514 KKASSERT((msg->ms_flags & MSGF_QUEUED) == 0);
515 KKASSERT(port == msg->ms_reply_port);
516 TAILQ_INSERT_TAIL(&port->mp_msgq, msg, ms_node);
517 msg->ms_flags |= MSGF_DONE | MSGF_QUEUED;
518 if (port->mp_flags & MSGPORTF_WAITING)
519 lwkt_schedule(port->mp_td);
520 } else if ((msg->ms_flags & (MSGF_QUEUED|MSGF_REPLY1)) == 0) {
522 * Abort on the target port. The message has not yet been replied
523 * and must be requeued to the target port.
525 msg->ms_flags |= MSGF_ABORTED | MSGF_QUEUED;
526 TAILQ_INSERT_TAIL(&port->mp_msgq, msg, ms_node);
527 if (port->mp_flags & MSGPORTF_WAITING)
528 lwkt_schedule(port->mp_td);
529 } else if ((msg->ms_flags & MSGF_REPLY1) == 0) {
531 * The message has not yet been retrieved by the target port, set
532 * MSGF_ABORTED so the target port can requeue the message abort after
535 msg->ms_flags |= MSGF_ABORTED;
540 * lwkt_default_waitport()
542 * If msg is NULL, dequeue the next message from the port's message
543 * queue, block until a message is ready. This function never
546 * If msg is non-NULL, block until the requested message has been returned
547 * to the port then dequeue and return it. DO NOT USE THIS TO WAIT FOR
548 * INCOMING REQUESTS, ONLY USE THIS TO WAIT FOR REPLIES.
550 * Note that the API does not currently support multiple threads waiting
551 * on a port. By virtue of owning the port it is controlled by our
552 * cpu and we can safely manipulate it's contents.
555 lwkt_default_waitport(lwkt_port_t port, lwkt_msg_t msg)
557 thread_t td = curthread;
560 KKASSERT(port->mp_td == td);
561 crit_enter_quick(td);
563 if ((msg = TAILQ_FIRST(&port->mp_msgq)) == NULL) {
564 port->mp_flags |= MSGPORTF_WAITING;
566 lwkt_deschedule_self(td);
568 } while ((msg = TAILQ_FIRST(&port->mp_msgq)) == NULL);
569 port->mp_flags &= ~MSGPORTF_WAITING;
571 _lwkt_pullmsg(port, msg);
574 * If a message is not marked done, or if it is queued, we have work
575 * to do. Note that MSGF_DONE is always set in the context of the
578 if ((msg->ms_flags & (MSGF_DONE|MSGF_QUEUED)) != MSGF_DONE) {
580 * We must own the reply port to safely mess with it's contents.
582 port = msg->ms_reply_port;
583 KKASSERT(port->mp_td == td);
585 if ((msg->ms_flags & MSGF_DONE) == 0) {
586 port->mp_flags |= MSGPORTF_WAITING; /* saved by the BGL */
590 * MSGF_PCATCH is only set by processes which wish to
591 * abort the message they are blocked on when a signal
592 * occurs. Note that we still must wait for message
593 * completion after sending an abort request.
595 if (msg->ms_flags & MSGF_PCATCH) {
596 if (sentabort == 0 && CURSIG(port->mp_td->td_proc)) {
601 lwkt_deschedule_self(td);
603 } while ((msg->ms_flags & MSGF_DONE) == 0);
604 port->mp_flags &= ~MSGPORTF_WAITING; /* saved by the BGL */
607 * We own the message now.
609 if (msg->ms_flags & MSGF_QUEUED) {
610 msg->ms_flags &= ~MSGF_QUEUED;
611 TAILQ_REMOVE(&port->mp_msgq, msg, ms_node);