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 1.21 2004/04/24 20:59:10 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>
80 #include <machine/cpufunc.h>
85 /************************************************************************
87 ************************************************************************/
89 static void lwkt_replyport_remote(lwkt_msg_t msg);
90 static void lwkt_putport_remote(lwkt_msg_t msg);
95 * Send a message asynchronously. This function requests asynchronous
96 * completion and calls lwkt_beginmsg(). If the target port decides to
97 * run the message synchronously this function will automatically queue
98 * the message to the current thread's message queue to present a
99 * consistent interface to the caller.
101 * The message's ms_cmd must be initialized and its ms_flags must
102 * be zero'd out. lwkt_sendmsg() will initialize the ms_abort_port
103 * (abort chasing port). If abort is supported, ms_abort must also be
106 * NOTE: you cannot safely request an abort until lwkt_sendmsg() returns
110 lwkt_sendmsg(lwkt_port_t port, lwkt_msg_t msg)
114 msg->ms_flags |= MSGF_ASYNC;
115 msg->ms_flags &= ~(MSGF_REPLY1 | MSGF_REPLY2 | MSGF_QUEUED | \
116 MSGF_ABORTED | MSGF_RETRIEVED);
117 KKASSERT(msg->ms_reply_port != NULL);
118 msg->ms_abort_port = msg->ms_reply_port;
119 if ((error = lwkt_beginmsg(port, msg)) != EASYNC) {
120 lwkt_replymsg(msg, error);
127 * Send a message synchronously. This function requests synchronous
128 * completion and calls lwkt_beginmsg(). If the target port decides to
129 * run the message asynchronously this function will block waiting for
130 * the message to complete. Since MSGF_ASYNC is not set the target
131 * will not attempt to queue the reply to a reply port but will simply
132 * wake up anyone waiting on the message.
134 * A synchronous error code is always returned.
136 * The message's ms_cmd must be initialized, and its ms_flags must be
137 * at least zero'd out. lwkt_domsg() will initialize the message's
138 * ms_abort_port (abort chasing port). If abort is supported, ms_abort
139 * must also be initialized.
141 * NOTE: you cannot safely request an abort until lwkt_domsg() blocks.
142 * XXX this probably needs some work.
145 lwkt_domsg(lwkt_port_t port, lwkt_msg_t msg)
149 msg->ms_flags &= ~(MSGF_ASYNC | MSGF_REPLY1 | MSGF_REPLY2 | \
150 MSGF_QUEUED | MSGF_ABORTED | MSGF_RETRIEVED);
151 KKASSERT(msg->ms_reply_port != NULL);
152 msg->ms_abort_port = msg->ms_reply_port;
153 if ((error = lwkt_beginmsg(port, msg)) == EASYNC) {
154 error = lwkt_waitmsg(msg);
159 /************************************************************************
161 ************************************************************************/
166 * Initialize a port for use and assign it to the specified thread.
169 lwkt_initport(lwkt_port_t port, thread_t td)
171 bzero(port, sizeof(*port));
172 TAILQ_INIT(&port->mp_msgq);
174 port->mp_putport = lwkt_default_putport;
175 port->mp_waitport = lwkt_default_waitport;
176 port->mp_replyport = lwkt_default_replyport;
177 port->mp_abortport = lwkt_default_abortport;
183 * Retrieve the next message from the port's message queue, return NULL
184 * if no messages are pending. Note that callers CANNOT use the
185 * MSGF_ABORTED flag as a litmus test to determine if a message
186 * was aborted. The flag only indicates that an abort was requested.
187 * The message's error code will indicate whether an abort occured
188 * (typically by returning EINTR).
190 * Note that once a message has been dequeued it is subject to being
191 * requeued via an IPI based abort request if it is not marked MSGF_DONE.
193 * If the message has been aborted we have to guarentee that abort
194 * semantics are properly followed. The target port will always see
195 * the original message at least once, and if it does not reply the
196 * message before looping on its message port again it will then see
197 * the message again with ms_cmd set to ms_abort.
199 * The calling thread MUST own the port.
204 _lwkt_pullmsg(lwkt_port_t port, lwkt_msg_t msg)
206 if ((msg->ms_flags & MSGF_ABORTED) == 0) {
208 * normal case, remove and return the message.
210 TAILQ_REMOVE(&port->mp_msgq, msg, ms_node);
211 msg->ms_flags = (msg->ms_flags & ~MSGF_QUEUED) | MSGF_RETRIEVED;
213 if (msg->ms_flags & MSGF_RETRIEVED) {
215 * abort case, message already returned once, remvoe and
216 * return the aborted message a second time after setting
217 * ms_cmd to ms_abort.
219 TAILQ_REMOVE(&port->mp_msgq, msg, ms_node);
220 msg->ms_flags &= ~MSGF_QUEUED;
221 msg->ms_cmd = msg->ms_abort;
224 * abort case, abort races initial message retrieval. The
225 * message is returned normally but not removed from the
226 * queue. On the next loop the 'aborted' message will be
227 * dequeued and returned. Note that if the caller replies
228 * to the message it will be dequeued (the abort becomes a
231 msg->ms_flags |= MSGF_RETRIEVED;
237 lwkt_getport(lwkt_port_t port)
241 KKASSERT(port->mp_td == curthread);
243 crit_enter_quick(port->mp_td);
244 if ((msg = TAILQ_FIRST(&port->mp_msgq)) != NULL)
245 _lwkt_pullmsg(port, msg);
246 crit_exit_quick(port->mp_td);
251 * This inline helper function completes processing of a reply from an
252 * unknown cpu context.
254 * The message is being returned to the specified port. The port is
255 * owned by the mp_td thread. If we are on the same cpu as the mp_td
256 * thread we can trivially queue the message to the reply port and schedule
257 * the target thread, otherwise we have to send an ipi message to the
260 * This inline must be entered with a critical section already held.
261 * Note that the IPIQ callback function (*_remote) is entered with a
262 * critical section already held, and we obtain one in lwkt_replyport().
266 _lwkt_replyport(lwkt_port_t port, lwkt_msg_t msg, int force)
268 thread_t td = port->mp_td;
270 if (force || td->td_gd == mycpu) {
272 * We can only reply the message if the abort has caught up with us,
273 * or if no abort was issued (same case).
275 if (msg->ms_abort_port == port) {
276 KKASSERT((msg->ms_flags & MSGF_QUEUED) == 0);
277 TAILQ_INSERT_TAIL(&port->mp_msgq, msg, ms_node);
278 msg->ms_flags |= MSGF_DONE | MSGF_QUEUED | MSGF_REPLY2;
279 if (port->mp_flags & MSGPORTF_WAITING)
283 lwkt_send_ipiq(td->td_gd, (ipifunc_t)lwkt_replyport_remote, msg);
288 * This function completes reply processing for the default case in the
289 * context of the originating cpu.
293 lwkt_replyport_remote(lwkt_msg_t msg)
295 _lwkt_replyport(msg->ms_reply_port, msg, 1);
299 * This function is called in the context of the target to reply a message.
300 * Note that the lwkt_replymsg() inline has already set MSGF_REPLY1 and
301 * entered a critical section for us.
305 lwkt_default_replyport(lwkt_port_t port, lwkt_msg_t msg)
308 msg->ms_flags |= MSGF_REPLY1;
309 if (msg->ms_flags & MSGF_ASYNC) {
311 * An abort may have caught up to us while we were processing the
312 * message. If this occured we have to dequeue the message from the
313 * target port in the context of our current cpu before we can
314 * finish replying it.
316 * If an abort occurs after we reply the MSGF_REPLY1 flag will
317 * prevent it from being requeued to the target port.
319 if (msg->ms_flags & MSGF_QUEUED) {
320 KKASSERT(msg->ms_flags & MSGF_ABORTED);
321 TAILQ_REMOVE(&msg->ms_target_port->mp_msgq, msg, ms_node);
322 msg->ms_flags &= ~MSGF_QUEUED;
324 _lwkt_replyport(port, msg, 0);
327 * Synchronously executed messages cannot be aborted and are just
328 * marked done. YYY MSGF_DONE should already be set, change flag set
331 msg->ms_flags |= MSGF_DONE;
332 if (port->mp_flags & MSGPORTF_WAITING)
333 lwkt_schedule(port->mp_td);
339 * lwkt_default_putport()
341 * This function is typically assigned to the mp_putport port vector.
343 * Queue a message to the target port and wakeup the thread owning it.
344 * This function always returns EASYNC and may be assigned to a
345 * message port's mp_putport function vector. Note that we must set
346 * MSGF_QUEUED prior to sending any IPIs in order to interlock against
347 * ABORT requests and other tests that might be performed.
349 * The inline must be called from a critical section (the remote function
350 * is called from an IPI and will be in a critical section).
355 _lwkt_putport(lwkt_port_t port, lwkt_msg_t msg, int force)
357 thread_t td = port->mp_td;
359 if (force || td->td_gd == mycpu) {
360 TAILQ_INSERT_TAIL(&port->mp_msgq, msg, ms_node);
361 if (port->mp_flags & MSGPORTF_WAITING)
364 lwkt_send_ipiq(td->td_gd, (ipifunc_t)lwkt_putport_remote, msg);
370 lwkt_putport_remote(lwkt_msg_t msg)
372 _lwkt_putport(msg->ms_target_port, msg, 1);
376 lwkt_default_putport(lwkt_port_t port, lwkt_msg_t msg)
379 msg->ms_flags |= MSGF_QUEUED; /* abort interlock */
380 msg->ms_flags &= ~MSGF_DONE;
381 msg->ms_target_port = port;
382 _lwkt_putport(port, msg, 0);
390 * Forward a message received on one port to another port. The forwarding
391 * function must deal with a pending abort but othewise essentially just
392 * issues a putport to the target port.
394 * An abort may have two side effects: First, the message may have been
395 * requeued to the current target port. If so, we must dequeue it before
399 lwkt_forwardmsg(lwkt_port_t port, lwkt_msg_t msg)
404 if (msg->ms_flags & MSGF_QUEUED) {
405 KKASSERT(msg->ms_flags & MSGF_ABORTED);
406 TAILQ_REMOVE(&msg->ms_target_port->mp_msgq, msg, ms_node);
407 msg->ms_flags &= ~MSGF_QUEUED;
409 msg->ms_flags &= ~MSGF_RETRIEVED;
410 if ((error = port->mp_putport(port, msg)) != EASYNC)
411 lwkt_replymsg(msg, error);
419 * Aborting a message is a fairly complex task. The first order of
420 * business is to get the message to the cpu that owns the target
421 * port, during which we may have to do some port chasing due to
422 * message forwarding operations.
424 * NOTE! Since an aborted message is requeued all message processing
425 * loops should check the MSGF_ABORTED flag.
427 static void lwkt_abortmsg_remote(lwkt_msg_t msg);
430 lwkt_abortmsg(lwkt_msg_t msg)
436 * A critical section protects us from reply IPIs on this cpu. We
437 * can only abort messages that have not yet completed (DONE), are not
438 * in the midst of being replied (REPLY1), and which support the
439 * abort function (ABORTABLE).
442 if ((msg->ms_flags & (MSGF_DONE|MSGF_REPLY1|MSGF_ABORTABLE)) == MSGF_ABORTABLE) {
444 * Chase the message. If REPLY1 is set the message has been replied
445 * all the way back to the originator, otherwise it is sitting on
446 * ms_target_port (but we can only complete processing if we are
447 * on the same cpu as the selected port in order to avoid
448 * SMP cache synchronization issues).
450 * When chasing through multiple ports ms_flags may not be
451 * synchronized to the current cpu, but it WILL be synchronized
452 * with regards to testing the MSGF_REPLY1 bit once we reach the
453 * target port that made the reply and since the cpu owning
454 * some port X stores the new port in ms_target_port if the message
455 * is forwarded, the current port will only ever equal the target
456 * port when we are on the correct cpu.
458 if (msg->ms_flags & MSGF_REPLY1)
459 port = msg->ms_reply_port;
461 port = msg->ms_target_port;
464 if (td->td_gd != mycpu) {
465 lwkt_send_ipiq(td->td_gd, (ipifunc_t)lwkt_abortmsg_remote, msg);
467 port->mp_abortport(port, msg);
475 lwkt_abortmsg_remote(lwkt_msg_t msg)
480 if (msg->ms_flags & MSGF_REPLY1)
481 port = msg->ms_reply_port;
483 port = msg->ms_target_port;
486 if (td->td_gd != mycpu) {
487 lwkt_send_ipiq(td->td_gd, (ipifunc_t)lwkt_abortmsg_remote, msg);
489 port->mp_abortport(port, msg);
494 * The mp_abortport function is called when the abort has finally caught up
495 * to the target port or (if the message has been replied) the reply port.
498 lwkt_default_abortport(lwkt_port_t port, lwkt_msg_t msg)
501 * Set ms_abort_port to ms_reply_port to indicate the completion of
502 * the messaging chasing portion of the abort request. Note that
503 * the passed port is the port that we finally caught up to, not
504 * necessarily the reply port.
506 msg->ms_abort_port = msg->ms_reply_port;
508 if (msg->ms_flags & MSGF_REPLY2) {
510 * If REPLY2 is set we must have chased it all the way back to
511 * the reply port, but the replyport code has not queued the message
512 * (because it was waiting for the abort to catch up). We become
513 * responsible for queueing the message to the reply port.
515 KKASSERT((msg->ms_flags & MSGF_QUEUED) == 0);
516 KKASSERT(port == msg->ms_reply_port);
517 TAILQ_INSERT_TAIL(&port->mp_msgq, msg, ms_node);
518 msg->ms_flags |= MSGF_DONE | MSGF_QUEUED;
519 if (port->mp_flags & MSGPORTF_WAITING)
520 lwkt_schedule(port->mp_td);
521 } else if ((msg->ms_flags & (MSGF_QUEUED|MSGF_REPLY1)) == 0) {
523 * Abort on the target port. The message has not yet been replied
524 * and must be requeued to the target port.
526 msg->ms_flags |= MSGF_ABORTED | MSGF_QUEUED;
527 TAILQ_INSERT_TAIL(&port->mp_msgq, msg, ms_node);
528 if (port->mp_flags & MSGPORTF_WAITING)
529 lwkt_schedule(port->mp_td);
530 } else if ((msg->ms_flags & MSGF_REPLY1) == 0) {
532 * The message has not yet been retrieved by the target port, set
533 * MSGF_ABORTED so the target port can requeue the message abort after
536 msg->ms_flags |= MSGF_ABORTED;
541 * lwkt_default_waitport()
543 * If msg is NULL, dequeue the next message from the port's message
544 * queue, block until a message is ready. This function never
547 * If msg is non-NULL, block until the requested message has been returned
548 * to the port then dequeue and return it. DO NOT USE THIS TO WAIT FOR
549 * INCOMING REQUESTS, ONLY USE THIS TO WAIT FOR REPLIES.
551 * Note that the API does not currently support multiple threads waiting
552 * on a port. By virtue of owning the port it is controlled by our
553 * cpu and we can safely manipulate it's contents.
556 lwkt_default_waitport(lwkt_port_t port, lwkt_msg_t msg)
558 thread_t td = curthread;
561 KKASSERT(port->mp_td == td);
562 crit_enter_quick(td);
564 if ((msg = TAILQ_FIRST(&port->mp_msgq)) == NULL) {
565 port->mp_flags |= MSGPORTF_WAITING;
567 lwkt_deschedule_self(td);
569 } while ((msg = TAILQ_FIRST(&port->mp_msgq)) == NULL);
570 port->mp_flags &= ~MSGPORTF_WAITING;
572 _lwkt_pullmsg(port, msg);
575 * If a message is not marked done, or if it is queued, we have work
576 * to do. Note that MSGF_DONE is always set in the context of the
579 if ((msg->ms_flags & (MSGF_DONE|MSGF_QUEUED)) != MSGF_DONE) {
581 * We must own the reply port to safely mess with it's contents.
583 port = msg->ms_reply_port;
584 KKASSERT(port->mp_td == td);
586 if ((msg->ms_flags & MSGF_DONE) == 0) {
587 port->mp_flags |= MSGPORTF_WAITING; /* saved by the BGL */
592 * MSGF_PCATCH is only set by processes which wish to
593 * abort the message they are blocked on when a signal
594 * occurs. Note that we still must wait for message
595 * completion after sending an abort request.
597 if (msg->ms_flags & MSGF_PCATCH) {
598 if (sentabort == 0 && CURSIG(port->mp_td->td_proc)) {
604 lwkt_deschedule_self(td);
606 } while ((msg->ms_flags & MSGF_DONE) == 0);
607 port->mp_flags &= ~MSGPORTF_WAITING; /* saved by the BGL */
610 * We own the message now.
612 if (msg->ms_flags & MSGF_QUEUED) {
613 msg->ms_flags &= ~MSGF_QUEUED;
614 TAILQ_REMOVE(&port->mp_msgq, msg, ms_node);