/* $OpenBSD: kern_synch.c,v 1.63 2005/05/29 03:20:41 deraadt Exp $ */ /* $NetBSD: kern_synch.c,v 1.37 1996/04/22 01:38:37 christos Exp $ */ /*- * Copyright (c) 1982, 1986, 1990, 1991, 1993 * The Regents of the University of California. All rights reserved. * (c) UNIX System Laboratories, Inc. * All or some portions of this file are derived from material licensed * to the University of California by American Telephone and Telegraph * Co. or Unix System Laboratories, Inc. and are reproduced herein with * the permission of UNIX System Laboratories, Inc. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * @(#)kern_synch.c 8.6 (Berkeley) 1/21/94 */ #include #include #include #include #include #include #include #include #include #include #ifdef KTRACE #include #endif void updatepri(struct proc *); void endtsleep(void *); /* * We're only looking at 7 bits of the address; everything is * aligned to 4, lots of things are aligned to greater powers * of 2. Shift right by 8, i.e. drop the bottom 256 worth. */ #define TABLESIZE 128 #define LOOKUP(x) (((long)(x) >> 8) & (TABLESIZE - 1)) struct slpque { struct proc *sq_head; struct proc **sq_tailp; } slpque[TABLESIZE]; /* * During autoconfiguration or after a panic, a sleep will simply * lower the priority briefly to allow interrupts, then return. * The priority to be used (safepri) is machine-dependent, thus this * value is initialized and maintained in the machine-dependent layers. * This priority will typically be 0, or the lowest priority * that is safe for use on the interrupt stack; it can be made * higher to block network software interrupts after panics. */ int safepri; /* * General sleep call. Suspends the current process until a wakeup is * performed on the specified identifier. The process will then be made * runnable with the specified priority. Sleeps at most timo/hz seconds * (0 means no timeout). If pri includes PCATCH flag, signals are checked * before and after sleeping, else signals are not checked. Returns 0 if * awakened, EWOULDBLOCK if the timeout expires. If PCATCH is set and a * signal needs to be delivered, ERESTART is returned if the current system * call should be restarted if possible, and EINTR is returned if the system * call should be interrupted by the signal (return EINTR). * * The interlock is held until the scheduler_slock (XXX) is held. The * interlock will be locked before returning back to the caller * unless the PNORELOCK flag is specified, in which case the * interlock will always be unlocked upon return. */ int ltsleep(ident, priority, wmesg, timo, interlock) void *ident; int priority, timo; const char *wmesg; volatile struct simplelock *interlock; { struct proc *p = curproc; struct slpque *qp; int s, sig; int catch = priority & PCATCH; int relock = (priority & PNORELOCK) == 0; if (cold || panicstr) { /* * After a panic, or during autoconfiguration, * just give interrupts a chance, then just return; * don't run any other procs or panic below, * in case this is the idle process and already asleep. */ s = splhigh(); splx(safepri); splx(s); if (interlock != NULL && relock == 0) simple_unlock(interlock); return (0); } #ifdef KTRACE if (KTRPOINT(p, KTR_CSW)) ktrcsw(p, 1, 0); #endif SCHED_LOCK(s); #ifdef DIAGNOSTIC if (ident == NULL || p->p_stat != SONPROC || p->p_back != NULL) panic("tsleep"); #endif p->p_wchan = ident; p->p_wmesg = wmesg; p->p_slptime = 0; p->p_priority = priority & PRIMASK; qp = &slpque[LOOKUP(ident)]; if (qp->sq_head == 0) qp->sq_head = p; else *qp->sq_tailp = p; *(qp->sq_tailp = &p->p_forw) = 0; if (timo) timeout_add(&p->p_sleep_to, timo); /* * We can now release the interlock; the scheduler_slock * is held, so a thread can't get in to do wakeup() before * we do the switch. * * XXX We leave the code block here, after inserting ourselves * on the sleep queue, because we might want a more clever * data structure for the sleep queues at some point. */ if (interlock != NULL) simple_unlock(interlock); /* * We put ourselves on the sleep queue and start our timeout * before calling CURSIG, as we could stop there, and a wakeup * or a SIGCONT (or both) could occur while we were stopped. * A SIGCONT would cause us to be marked as SSLEEP * without resuming us, thus we must be ready for sleep * when CURSIG is called. If the wakeup happens while we're * stopped, p->p_wchan will be 0 upon return from CURSIG. */ if (catch) { p->p_flag |= P_SINTR; if ((sig = CURSIG(p)) != 0) { if (p->p_wchan) unsleep(p); p->p_stat = SONPROC; SCHED_UNLOCK(s); goto resume; } if (p->p_wchan == 0) { catch = 0; SCHED_UNLOCK(s); goto resume; } } else sig = 0; p->p_stat = SSLEEP; p->p_stats->p_ru.ru_nvcsw++; SCHED_ASSERT_LOCKED(); mi_switch(); #ifdef DDB /* handy breakpoint location after process "wakes" */ __asm(".globl bpendtsleep\nbpendtsleep:"); #endif SCHED_ASSERT_UNLOCKED(); /* * Note! this splx belongs to the SCHED_LOCK(s) above, mi_switch * releases the scheduler lock, but does not lower the spl. */ splx(s); resume: #ifdef __HAVE_CPUINFO p->p_cpu->ci_schedstate.spc_curpriority = p->p_usrpri; #else curpriority = p->p_usrpri; #endif p->p_flag &= ~P_SINTR; if (p->p_flag & P_TIMEOUT) { p->p_flag &= ~P_TIMEOUT; if (sig == 0) { #ifdef KTRACE if (KTRPOINT(p, KTR_CSW)) ktrcsw(p, 0, 0); #endif if (interlock != NULL && relock) simple_lock(interlock); return (EWOULDBLOCK); } } else if (timo) timeout_del(&p->p_sleep_to); if (catch && (sig != 0 || (sig = CURSIG(p)) != 0)) { #ifdef KTRACE if (KTRPOINT(p, KTR_CSW)) ktrcsw(p, 0, 0); #endif if (interlock != NULL && relock) simple_lock(interlock); if (p->p_sigacts->ps_sigintr & sigmask(sig)) return (EINTR); return (ERESTART); } #ifdef KTRACE if (KTRPOINT(p, KTR_CSW)) ktrcsw(p, 0, 0); #endif if (interlock != NULL && relock) simple_lock(interlock); return (0); } /* * Implement timeout for tsleep. * If process hasn't been awakened (wchan non-zero), * set timeout flag and undo the sleep. If proc * is stopped, just unsleep so it will remain stopped. */ void endtsleep(arg) void *arg; { struct proc *p; int s; p = (struct proc *)arg; SCHED_LOCK(s); if (p->p_wchan) { if (p->p_stat == SSLEEP) setrunnable(p); else unsleep(p); p->p_flag |= P_TIMEOUT; } SCHED_UNLOCK(s); } /* * Remove a process from its wait queue */ void unsleep(p) register struct proc *p; { register struct slpque *qp; register struct proc **hp; #if 0 int s; /* * XXX we cannot do recursive SCHED_LOCKing yet. All callers lock * anyhow. */ SCHED_LOCK(s); #endif if (p->p_wchan) { hp = &(qp = &slpque[LOOKUP(p->p_wchan)])->sq_head; while (*hp != p) hp = &(*hp)->p_forw; *hp = p->p_forw; if (qp->sq_tailp == &p->p_forw) qp->sq_tailp = hp; p->p_wchan = 0; } #if 0 SCHED_UNLOCK(s); #endif } /* * Make all processes sleeping on the specified identifier runnable. */ void wakeup_n(ident, n) void *ident; int n; { struct slpque *qp; struct proc *p, **q; int s; SCHED_LOCK(s); qp = &slpque[LOOKUP(ident)]; restart: for (q = &qp->sq_head; (p = *q) != NULL; ) { #ifdef DIAGNOSTIC if (p->p_back || (p->p_stat != SSLEEP && p->p_stat != SSTOP)) panic("wakeup"); #endif if (p->p_wchan == ident) { --n; p->p_wchan = 0; *q = p->p_forw; if (qp->sq_tailp == &p->p_forw) qp->sq_tailp = q; if (p->p_stat == SSLEEP) { /* OPTIMIZED EXPANSION OF setrunnable(p); */ if (p->p_slptime > 1) updatepri(p); p->p_slptime = 0; p->p_stat = SRUN; /* * Since curpriority is a user priority, * p->p_priority is always better than * curpriority on the last CPU on * which it ran. * * XXXSMP See affinity comment in * resched_proc(). */ if ((p->p_flag & P_INMEM) != 0) { setrunqueue(p); #ifdef __HAVE_CPUINFO KASSERT(p->p_cpu != NULL); need_resched(p->p_cpu); #else need_resched(0); #endif } else { wakeup((caddr_t)&proc0); } /* END INLINE EXPANSION */ if (n != 0) goto restart; else break; } } else q = &p->p_forw; } SCHED_UNLOCK(s); } void wakeup(chan) void *chan; { wakeup_n(chan, -1); }