2 * Copyright (c) 2003,2004 The DragonFly Project. All rights reserved.
4 * This code is derived from software contributed to The DragonFly Project
5 * by Matthew Dillon <dillon@backplane.com>
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in
15 * the documentation and/or other materials provided with the
17 * 3. Neither the name of The DragonFly Project nor the names of its
18 * contributors may be used to endorse or promote products derived
19 * from this software without specific, prior written permission.
21 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
22 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
23 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
24 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
25 * COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
26 * INCIDENTAL, SPECIAL, EXEMPLARY OR CONSEQUENTIAL DAMAGES (INCLUDING,
27 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
28 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
29 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
30 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
31 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34 * NOTE! This file may be compiled for userland libraries as well as for
37 * $DragonFly: src/sys/kern/lwkt_msgport.c,v 1.29 2004/07/24 20:21:35 dillon Exp $
42 #include <sys/param.h>
43 #include <sys/systm.h>
44 #include <sys/kernel.h>
46 #include <sys/rtprio.h>
47 #include <sys/queue.h>
48 #include <sys/sysctl.h>
49 #include <sys/kthread.h>
50 #include <sys/signalvar.h>
51 #include <machine/cpu.h>
55 #include <vm/vm_param.h>
56 #include <vm/vm_kern.h>
57 #include <vm/vm_object.h>
58 #include <vm/vm_page.h>
59 #include <vm/vm_map.h>
60 #include <vm/vm_pager.h>
61 #include <vm/vm_extern.h>
62 #include <vm/vm_zone.h>
64 #include <sys/thread2.h>
65 #include <sys/msgport2.h>
67 #include <machine/stdarg.h>
68 #include <machine/ipl.h>
69 #include <machine/cpufunc.h>
71 #include <machine/smp.h>
74 #include <sys/malloc.h>
75 MALLOC_DEFINE(M_LWKTMSG, "lwkt message", "lwkt message");
79 #include <sys/stdint.h>
80 #include <libcaps/thread.h>
81 #include <sys/thread.h>
82 #include <sys/msgport.h>
83 #include <sys/errno.h>
84 #include <libcaps/globaldata.h>
85 #include <machine/cpufunc.h>
86 #include <sys/thread2.h>
87 #include <sys/msgport2.h>
93 /************************************************************************
95 ************************************************************************/
97 static void lwkt_replyport_remote(lwkt_msg_t msg);
98 static void lwkt_putport_remote(lwkt_msg_t msg);
103 * Send a message asynchronously. This function requests asynchronous
104 * completion and calls lwkt_beginmsg(). If the target port decides to
105 * run the message synchronously this function will automatically queue
106 * the message to the current thread's message queue to present a
107 * consistent interface to the caller.
109 * The message's ms_cmd must be initialized and its ms_flags must
110 * be zero'd out. lwkt_sendmsg() will initialize the ms_abort_port
111 * (abort chasing port). If abort is supported, ms_abort must also be
114 * NOTE: you cannot safely request an abort until lwkt_sendmsg() returns
117 * NOTE: MSGF_DONE is left set. The target port must clear it if the
118 * message is to be handled asynchronously, while the synchronous case
119 * can just ignore it.
122 lwkt_sendmsg(lwkt_port_t port, lwkt_msg_t msg)
126 msg->ms_flags |= MSGF_ASYNC;
127 msg->ms_flags &= ~(MSGF_REPLY1 | MSGF_REPLY2 | MSGF_QUEUED | \
128 MSGF_ABORTED | MSGF_RETRIEVED);
129 KKASSERT(msg->ms_reply_port != NULL);
130 msg->ms_abort_port = msg->ms_reply_port;
131 if ((error = lwkt_beginmsg(port, msg)) != EASYNC) {
132 lwkt_replymsg(msg, error);
139 * Send a message synchronously. This function requests synchronous
140 * completion and calls lwkt_beginmsg(). If the target port decides to
141 * run the message asynchronously this function will block waiting for
142 * the message to complete. Since MSGF_ASYNC is not set the target
143 * will not attempt to queue the reply to a reply port but will simply
144 * wake up anyone waiting on the message.
146 * A synchronous error code is always returned.
148 * The message's ms_cmd must be initialized, and its ms_flags must be
149 * at least zero'd out. lwkt_domsg() will initialize the message's
150 * ms_abort_port (abort chasing port). If abort is supported, ms_abort
151 * must also be initialized.
153 * NOTE: you cannot safely request an abort until lwkt_domsg() blocks.
154 * XXX this probably needs some work.
156 * NOTE: MSGF_DONE is left set. The target port must clear it if the
157 * message is to be handled asynchronously, while the synchronous case
158 * can just ignore it.
161 lwkt_domsg(lwkt_port_t port, lwkt_msg_t msg)
165 msg->ms_flags &= ~(MSGF_ASYNC | MSGF_REPLY1 | MSGF_REPLY2 | \
166 MSGF_QUEUED | MSGF_ABORTED | MSGF_RETRIEVED);
167 KKASSERT(msg->ms_reply_port != NULL);
168 msg->ms_abort_port = msg->ms_reply_port;
169 if ((error = lwkt_beginmsg(port, msg)) == EASYNC) {
170 error = lwkt_waitmsg(msg);
175 /************************************************************************
177 ************************************************************************/
182 * Initialize a port for use and assign it to the specified thread.
185 lwkt_initport(lwkt_port_t port, thread_t td)
187 bzero(port, sizeof(*port));
188 TAILQ_INIT(&port->mp_msgq);
190 port->mp_putport = lwkt_default_putport;
191 port->mp_waitport = lwkt_default_waitport;
192 port->mp_replyport = lwkt_default_replyport;
193 port->mp_abortport = lwkt_default_abortport;
199 * Retrieve the next message from the port's message queue, return NULL
200 * if no messages are pending. Note that callers CANNOT use the
201 * MSGF_ABORTED flag as a litmus test to determine if a message
202 * was aborted. The flag only indicates that an abort was requested.
203 * The message's error code will indicate whether an abort occured
204 * (typically by returning EINTR).
206 * Note that once a message has been dequeued it is subject to being
207 * requeued via an IPI based abort request if it is not marked MSGF_DONE.
209 * If the message has been aborted we have to guarentee that abort
210 * semantics are properly followed. The target port will always see
211 * the original message at least once, and if it does not reply the
212 * message before looping on its message port again it will then see
213 * the message again with ms_cmd set to ms_abort.
215 * The calling thread MUST own the port.
220 _lwkt_pullmsg(lwkt_port_t port, lwkt_msg_t msg)
222 if ((msg->ms_flags & MSGF_ABORTED) == 0) {
224 * normal case, remove and return the message.
226 TAILQ_REMOVE(&port->mp_msgq, msg, ms_node);
227 msg->ms_flags = (msg->ms_flags & ~MSGF_QUEUED) | MSGF_RETRIEVED;
229 if (msg->ms_flags & MSGF_RETRIEVED) {
231 * abort case, message already returned once, remvoe and
232 * return the aborted message a second time after setting
233 * ms_cmd to ms_abort.
235 TAILQ_REMOVE(&port->mp_msgq, msg, ms_node);
236 msg->ms_flags &= ~MSGF_QUEUED;
237 msg->ms_cmd = msg->ms_abort;
240 * abort case, abort races initial message retrieval. The
241 * message is returned normally but not removed from the
242 * queue. On the next loop the 'aborted' message will be
243 * dequeued and returned. Note that if the caller replies
244 * to the message it will be dequeued (the abort becomes a
247 msg->ms_flags |= MSGF_RETRIEVED;
253 lwkt_getport(lwkt_port_t port)
257 KKASSERT(port->mp_td == curthread);
259 crit_enter_quick(port->mp_td);
260 if ((msg = TAILQ_FIRST(&port->mp_msgq)) != NULL)
261 _lwkt_pullmsg(port, msg);
262 crit_exit_quick(port->mp_td);
267 * This inline helper function completes processing of a reply from an
268 * unknown cpu context.
270 * The message is being returned to the specified port. The port is
271 * owned by the mp_td thread. If we are on the same cpu as the mp_td
272 * thread we can trivially queue the message to the reply port and schedule
273 * the target thread, otherwise we have to send an ipi message to the
276 * This inline must be entered with a critical section already held.
277 * Note that the IPIQ callback function (*_remote) is entered with a
278 * critical section already held, and we obtain one in lwkt_replyport().
282 _lwkt_replyport(lwkt_port_t port, lwkt_msg_t msg, int force)
284 thread_t td = port->mp_td;
286 if (force || td->td_gd == mycpu) {
288 * We can only reply the message if the abort has caught up with us,
289 * or if no abort was issued (same case).
291 if (msg->ms_abort_port == port) {
292 KKASSERT((msg->ms_flags & MSGF_QUEUED) == 0);
293 TAILQ_INSERT_TAIL(&port->mp_msgq, msg, ms_node);
294 msg->ms_flags |= MSGF_DONE | MSGF_QUEUED | MSGF_REPLY2;
295 if (port->mp_flags & MSGPORTF_WAITING)
299 lwkt_send_ipiq(td->td_gd, (ipifunc_t)lwkt_replyport_remote, msg);
304 * This function completes reply processing for the default case in the
305 * context of the originating cpu.
309 lwkt_replyport_remote(lwkt_msg_t msg)
311 _lwkt_replyport(msg->ms_reply_port, msg, 1);
315 * This function is called in the context of the target to reply a message.
316 * The critical section protects us from IPIs on the this CPU.
320 lwkt_default_replyport(lwkt_port_t port, lwkt_msg_t msg)
323 msg->ms_flags |= MSGF_REPLY1;
326 * An abort may have caught up to us while we were processing the
327 * message. If this occured we have to dequeue the message from the
328 * target port in the context of our current cpu before we can finish
331 if (msg->ms_flags & MSGF_QUEUED) {
332 KKASSERT(msg->ms_flags & MSGF_ABORTED);
333 TAILQ_REMOVE(&msg->ms_target_port->mp_msgq, msg, ms_node);
334 msg->ms_flags &= ~MSGF_QUEUED;
338 * Do reply port processing for async messages. Just mark the message
339 * done and wakeup the owner of the reply port for synchronous messages.
341 if (msg->ms_flags & MSGF_ASYNC) {
342 _lwkt_replyport(port, msg, 0);
344 msg->ms_flags |= MSGF_DONE;
345 if (port->mp_flags & MSGPORTF_WAITING)
346 lwkt_schedule(port->mp_td);
352 * lwkt_default_putport()
354 * This function is typically assigned to the mp_putport port vector.
356 * Queue a message to the target port and wakeup the thread owning it.
357 * This function always returns EASYNC and may be assigned to a
358 * message port's mp_putport function vector. Note that we must set
359 * MSGF_QUEUED prior to sending any IPIs in order to interlock against
360 * ABORT requests and other tests that might be performed.
362 * Note that messages start out as synchronous entities, and as an
363 * optimization MSGF_DONE is usually left set (so in the synchronous path
364 * no modifications to ms_flags are ever required). If a message becomes
365 * async, i.e. you return EASYNC, then MSGF_DONE must be cleared or
366 * lwkt_replymsg() will wind up being a NOP.
368 * The inline must be called from a critical section (the remote function
369 * is called from an IPI and will be in a critical section).
374 _lwkt_putport(lwkt_port_t port, lwkt_msg_t msg, int force)
376 thread_t td = port->mp_td;
378 if (force || td->td_gd == mycpu) {
379 TAILQ_INSERT_TAIL(&port->mp_msgq, msg, ms_node);
380 if (port->mp_flags & MSGPORTF_WAITING)
383 lwkt_send_ipiq(td->td_gd, (ipifunc_t)lwkt_putport_remote, msg);
389 lwkt_putport_remote(lwkt_msg_t msg)
391 _lwkt_putport(msg->ms_target_port, msg, 1);
395 lwkt_default_putport(lwkt_port_t port, lwkt_msg_t msg)
398 msg->ms_flags |= MSGF_QUEUED; /* abort interlock */
399 msg->ms_flags &= ~MSGF_DONE;
400 msg->ms_target_port = port;
401 _lwkt_putport(port, msg, 0);
409 * Forward a message received on one port to another port. The forwarding
410 * function must deal with a pending abort but othewise essentially just
411 * issues a putport to the target port.
413 * An abort may have two side effects: First, the message may have been
414 * requeued to the current target port. If so, we must dequeue it before
418 lwkt_forwardmsg(lwkt_port_t port, lwkt_msg_t msg)
423 if (msg->ms_flags & MSGF_QUEUED) {
424 KKASSERT(msg->ms_flags & MSGF_ABORTED);
425 TAILQ_REMOVE(&msg->ms_target_port->mp_msgq, msg, ms_node);
426 msg->ms_flags &= ~MSGF_QUEUED;
428 msg->ms_flags &= ~MSGF_RETRIEVED;
429 if ((error = port->mp_putport(port, msg)) != EASYNC)
430 lwkt_replymsg(msg, error);
438 * Aborting a message is a fairly complex task. The first order of
439 * business is to get the message to the cpu that owns the target
440 * port, during which we may have to do some port chasing due to
441 * message forwarding operations.
443 * NOTE! Since an aborted message is requeued all message processing
444 * loops should check the MSGF_ABORTED flag.
446 static void lwkt_abortmsg_remote(lwkt_msg_t msg);
449 lwkt_abortmsg(lwkt_msg_t msg)
455 * A critical section protects us from reply IPIs on this cpu. We
456 * can only abort messages that have not yet completed (DONE), are not
457 * in the midst of being replied (REPLY1), and which support the
458 * abort function (ABORTABLE).
461 if ((msg->ms_flags & (MSGF_DONE|MSGF_REPLY1|MSGF_ABORTABLE)) == MSGF_ABORTABLE) {
463 * Chase the message. If REPLY1 is set the message has been replied
464 * all the way back to the originator, otherwise it is sitting on
465 * ms_target_port (but we can only complete processing if we are
466 * on the same cpu as the selected port in order to avoid
467 * SMP cache synchronization issues).
469 * When chasing through multiple ports ms_flags may not be
470 * synchronized to the current cpu, but it WILL be synchronized
471 * with regards to testing the MSGF_REPLY1 bit once we reach the
472 * target port that made the reply and since the cpu owning
473 * some port X stores the new port in ms_target_port if the message
474 * is forwarded, the current port will only ever equal the target
475 * port when we are on the correct cpu.
477 if (msg->ms_flags & MSGF_REPLY1)
478 port = msg->ms_reply_port;
480 port = msg->ms_target_port;
484 * The chase call must run on the cpu owning the port. Fully
485 * synchronous ports (mp_td == NULL) can run the call on any cpu.
488 if (td && td->td_gd != mycpu) {
489 lwkt_send_ipiq(td->td_gd, (ipifunc_t)lwkt_abortmsg_remote, msg);
491 port->mp_abortport(port, msg);
499 lwkt_abortmsg_remote(lwkt_msg_t msg)
504 if (msg->ms_flags & MSGF_REPLY1)
505 port = msg->ms_reply_port;
507 port = msg->ms_target_port;
510 if (td->td_gd != mycpu) {
511 lwkt_send_ipiq(td->td_gd, (ipifunc_t)lwkt_abortmsg_remote, msg);
513 port->mp_abortport(port, msg);
518 * The mp_abortport function is called when the abort has finally caught up
519 * to the target port or (if the message has been replied) the reply port.
522 lwkt_default_abortport(lwkt_port_t port, lwkt_msg_t msg)
525 * Set ms_abort_port to ms_reply_port to indicate the completion of
526 * the messaging chasing portion of the abort request. Note that
527 * the passed port is the port that we finally caught up to, not
528 * necessarily the reply port.
530 msg->ms_abort_port = msg->ms_reply_port;
532 if (msg->ms_flags & MSGF_REPLY2) {
534 * If REPLY2 is set we must have chased it all the way back to
535 * the reply port, but the replyport code has not queued the message
536 * (because it was waiting for the abort to catch up). We become
537 * responsible for queueing the message to the reply port.
539 KKASSERT((msg->ms_flags & MSGF_QUEUED) == 0);
540 KKASSERT(port == msg->ms_reply_port);
541 TAILQ_INSERT_TAIL(&port->mp_msgq, msg, ms_node);
542 msg->ms_flags |= MSGF_DONE | MSGF_QUEUED;
543 if (port->mp_flags & MSGPORTF_WAITING)
544 lwkt_schedule(port->mp_td);
545 } else if ((msg->ms_flags & (MSGF_QUEUED|MSGF_REPLY1)) == 0) {
547 * Abort on the target port. The message has not yet been replied
548 * and must be requeued to the target port.
550 msg->ms_flags |= MSGF_ABORTED | MSGF_QUEUED;
551 TAILQ_INSERT_TAIL(&port->mp_msgq, msg, ms_node);
552 if (port->mp_flags & MSGPORTF_WAITING)
553 lwkt_schedule(port->mp_td);
554 } else if ((msg->ms_flags & MSGF_REPLY1) == 0) {
556 * The message has not yet been retrieved by the target port, set
557 * MSGF_ABORTED so the target port can requeue the message abort after
560 msg->ms_flags |= MSGF_ABORTED;
565 * lwkt_default_waitport()
567 * If msg is NULL, dequeue the next message from the port's message
568 * queue, block until a message is ready. This function never
571 * If msg is non-NULL, block until the requested message has been returned
572 * to the port then dequeue and return it. DO NOT USE THIS TO WAIT FOR
573 * INCOMING REQUESTS, ONLY USE THIS TO WAIT FOR REPLIES.
575 * Note that the API does not currently support multiple threads waiting
576 * on a port. By virtue of owning the port it is controlled by our
577 * cpu and we can safely manipulate it's contents.
580 lwkt_default_waitport(lwkt_port_t port, lwkt_msg_t msg)
582 thread_t td = curthread;
585 KKASSERT(port->mp_td == td);
586 crit_enter_quick(td);
588 if ((msg = TAILQ_FIRST(&port->mp_msgq)) == NULL) {
589 port->mp_flags |= MSGPORTF_WAITING;
590 td->td_flags |= TDF_BLOCKED;
592 lwkt_deschedule_self(td);
594 } while ((msg = TAILQ_FIRST(&port->mp_msgq)) == NULL);
595 td->td_flags &= ~TDF_BLOCKED;
596 port->mp_flags &= ~MSGPORTF_WAITING;
598 _lwkt_pullmsg(port, msg);
601 * If a message is not marked done, or if it is queued, we have work
602 * to do. Note that MSGF_DONE is always set in the context of the
605 if ((msg->ms_flags & (MSGF_DONE|MSGF_QUEUED)) != MSGF_DONE) {
607 * We must own the reply port to safely mess with it's contents.
609 port = msg->ms_reply_port;
610 KKASSERT(port->mp_td == td);
612 if ((msg->ms_flags & MSGF_DONE) == 0) {
613 port->mp_flags |= MSGPORTF_WAITING; /* saved by the BGL */
618 * MSGF_PCATCH is only set by processes which wish to
619 * abort the message they are blocked on when a signal
620 * occurs. Note that we still must wait for message
621 * completion after sending an abort request.
623 if (msg->ms_flags & MSGF_PCATCH) {
624 if (sentabort == 0 && CURSIG(port->mp_td->td_proc)) {
632 * XXX set TDF_SINTR so 'ps' knows the difference between
633 * an interruptable wait and a disk wait. YYY eventually
634 * move P_SINTR to TDF_SINTR to reduce duplication.
636 td->td_flags |= TDF_SINTR | TDF_BLOCKED;
637 lwkt_deschedule_self(td);
639 td->td_flags &= ~(TDF_SINTR | TDF_BLOCKED);
640 } while ((msg->ms_flags & MSGF_DONE) == 0);
641 port->mp_flags &= ~MSGPORTF_WAITING; /* saved by the BGL */
644 * We own the message now.
646 if (msg->ms_flags & MSGF_QUEUED) {
647 msg->ms_flags &= ~MSGF_QUEUED;
648 TAILQ_REMOVE(&port->mp_msgq, msg, ms_node);