/* $NetBSD: kern_lwp.c,v 1.29 2005/02/12 21:39:00 fvdl Exp $ */ /*- * Copyright (c) 2001 The NetBSD Foundation, Inc. * All rights reserved. * * This code is derived from software contributed to The NetBSD Foundation * by Nathan J. Williams. * * 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. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by the NetBSD * Foundation, Inc. and its contributors. * 4. Neither the name of The NetBSD Foundation 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 NETBSD FOUNDATION, INC. 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 FOUNDATION 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. */ #include __KERNEL_RCSID(0, "$NetBSD: kern_lwp.c,v 1.29 2005/02/12 21:39:00 fvdl Exp $"); #include "opt_multiprocessor.h" #include #include #include #include #include #include #include #include #include #include #include #include #include struct lwplist alllwp; #define LWP_DEBUG #ifdef LWP_DEBUG int lwp_debug = 0; #define DPRINTF(x) if (lwp_debug) printf x #else #define DPRINTF(x) #endif /* ARGSUSED */ int sys__lwp_create(struct lwp *l, void *v, register_t *retval) { struct sys__lwp_create_args /* { syscallarg(const ucontext_t *) ucp; syscallarg(u_long) flags; syscallarg(lwpid_t *) new_lwp; } */ *uap = v; struct proc *p = l->l_proc; struct lwp *l2; vaddr_t uaddr; boolean_t inmem; ucontext_t *newuc; int s, error; newuc = pool_get(&lwp_uc_pool, PR_WAITOK); error = copyin(SCARG(uap, ucp), newuc, sizeof(*newuc)); if (error) return (error); /* XXX check against resource limits */ inmem = uvm_uarea_alloc(&uaddr); if (__predict_false(uaddr == 0)) { return (ENOMEM); } /* XXX flags: * __LWP_ASLWP is probably needed for Solaris compat. */ newlwp(l, p, uaddr, inmem, SCARG(uap, flags) & LWP_DETACHED, NULL, 0, startlwp, newuc, &l2); if ((SCARG(uap, flags) & LWP_SUSPENDED) == 0) { SCHED_LOCK(s); l2->l_stat = LSRUN; setrunqueue(l2); SCHED_UNLOCK(s); simple_lock(&p->p_lock); p->p_nrlwps++; simple_unlock(&p->p_lock); } else { l2->l_stat = LSSUSPENDED; } error = copyout(&l2->l_lid, SCARG(uap, new_lwp), sizeof(l2->l_lid)); if (error) return (error); return (0); } int sys__lwp_exit(struct lwp *l, void *v, register_t *retval) { lwp_exit(l); /* NOTREACHED */ return (0); } int sys__lwp_self(struct lwp *l, void *v, register_t *retval) { *retval = l->l_lid; return (0); } int sys__lwp_getprivate(struct lwp *l, void *v, register_t *retval) { *retval = (uintptr_t) l->l_private; return (0); } int sys__lwp_setprivate(struct lwp *l, void *v, register_t *retval) { struct sys__lwp_setprivate_args /* { syscallarg(void *) ptr; } */ *uap = v; l->l_private = SCARG(uap, ptr); return (0); } int sys__lwp_suspend(struct lwp *l, void *v, register_t *retval) { struct sys__lwp_suspend_args /* { syscallarg(lwpid_t) target; } */ *uap = v; int target_lid; struct proc *p = l->l_proc; struct lwp *t; struct lwp *t2; target_lid = SCARG(uap, target); LIST_FOREACH(t, &p->p_lwps, l_sibling) if (t->l_lid == target_lid) break; if (t == NULL) return (ESRCH); if (t == l) { /* * Check for deadlock, which is only possible * when we're suspending ourself. */ LIST_FOREACH(t2, &p->p_lwps, l_sibling) { if ((t2 != l) && (t2->l_stat != LSSUSPENDED)) break; } if (t2 == NULL) /* All other LWPs are suspended */ return (EDEADLK); } return lwp_suspend(l, t); } inline int lwp_suspend(struct lwp *l, struct lwp *t) { struct proc *p = t->l_proc; int s; if (t == l) { SCHED_LOCK(s); l->l_stat = LSSUSPENDED; /* XXX NJWLWP check if this makes sense here: */ p->p_stats->p_ru.ru_nvcsw++; mi_switch(l, NULL); SCHED_ASSERT_UNLOCKED(); splx(s); } else { switch (t->l_stat) { case LSSUSPENDED: return (0); /* _lwp_suspend() is idempotent */ case LSRUN: SCHED_LOCK(s); remrunqueue(t); t->l_stat = LSSUSPENDED; SCHED_UNLOCK(s); simple_lock(&p->p_lock); p->p_nrlwps--; simple_unlock(&p->p_lock); break; case LSSLEEP: t->l_stat = LSSUSPENDED; break; case LSIDL: case LSZOMB: return (EINTR); /* It's what Solaris does..... */ case LSSTOP: panic("_lwp_suspend: Stopped LWP in running process!"); break; case LSONPROC: /* XXX multiprocessor LWPs? Implement me! */ return (EINVAL); } } return (0); } int sys__lwp_continue(struct lwp *l, void *v, register_t *retval) { struct sys__lwp_continue_args /* { syscallarg(lwpid_t) target; } */ *uap = v; int s, target_lid; struct proc *p = l->l_proc; struct lwp *t; target_lid = SCARG(uap, target); LIST_FOREACH(t, &p->p_lwps, l_sibling) if (t->l_lid == target_lid) break; if (t == NULL) return (ESRCH); SCHED_LOCK(s); lwp_continue(t); SCHED_UNLOCK(s); return (0); } void lwp_continue(struct lwp *l) { DPRINTF(("lwp_continue of %d.%d (%s), state %d, wchan %p\n", l->l_proc->p_pid, l->l_lid, l->l_proc->p_comm, l->l_stat, l->l_wchan)); if (l->l_stat != LSSUSPENDED) return; if (l->l_wchan == 0) { /* LWP was runnable before being suspended. */ setrunnable(l); } else { /* LWP was sleeping before being suspended. */ l->l_stat = LSSLEEP; } } int sys__lwp_wakeup(struct lwp *l, void *v, register_t *retval) { struct sys__lwp_wakeup_args /* { syscallarg(lwpid_t) target; } */ *uap = v; lwpid_t target_lid; struct lwp *t; struct proc *p; int error; int s; p = l->l_proc; target_lid = SCARG(uap, target); SCHED_LOCK(s); LIST_FOREACH(t, &p->p_lwps, l_sibling) if (t->l_lid == target_lid) break; if (t == NULL) { error = ESRCH; goto exit; } if (t->l_stat != LSSLEEP) { error = ENODEV; goto exit; } if ((t->l_flag & L_SINTR) == 0) { error = EBUSY; goto exit; } /* * Tell ltsleep to wakeup. */ t->l_flag |= L_CANCELLED; setrunnable(t); error = 0; exit: SCHED_UNLOCK(s); return error; } int sys__lwp_wait(struct lwp *l, void *v, register_t *retval) { struct sys__lwp_wait_args /* { syscallarg(lwpid_t) wait_for; syscallarg(lwpid_t *) departed; } */ *uap = v; int error; lwpid_t dep; error = lwp_wait1(l, SCARG(uap, wait_for), &dep, 0); if (error) return (error); if (SCARG(uap, departed)) { error = copyout(&dep, SCARG(uap, departed), sizeof(dep)); if (error) return (error); } return (0); } int lwp_wait1(struct lwp *l, lwpid_t lid, lwpid_t *departed, int flags) { struct proc *p = l->l_proc; struct lwp *l2, *l3; int nfound, error, wpri; static const char waitstr1[] = "lwpwait"; static const char waitstr2[] = "lwpwait2"; DPRINTF(("lwp_wait1: %d.%d waiting for %d.\n", p->p_pid, l->l_lid, lid)); if (lid == l->l_lid) return (EDEADLK); /* Waiting for ourselves makes no sense. */ wpri = PWAIT | ((flags & LWPWAIT_EXITCONTROL) ? PNOEXITERR : PCATCH); loop: nfound = 0; LIST_FOREACH(l2, &p->p_lwps, l_sibling) { if ((l2 == l) || (l2->l_flag & L_DETACHED) || ((lid != 0) && (lid != l2->l_lid))) continue; nfound++; if (l2->l_stat == LSZOMB) { if (departed) *departed = l2->l_lid; simple_lock(&p->p_lock); LIST_REMOVE(l2, l_sibling); p->p_nlwps--; p->p_nzlwps--; simple_unlock(&p->p_lock); /* XXX decrement limits */ pool_put(&lwp_pool, l2); return (0); } else if (l2->l_stat == LSSLEEP || l2->l_stat == LSSUSPENDED) { /* Deadlock checks. * 1. If all other LWPs are waiting for exits * or suspended, we would deadlock. */ LIST_FOREACH(l3, &p->p_lwps, l_sibling) { if (l3 != l && (l3->l_stat != LSSUSPENDED) && !(l3->l_stat == LSSLEEP && l3->l_wchan == (caddr_t) &p->p_nlwps)) break; } if (l3 == NULL) /* Everyone else is waiting. */ return (EDEADLK); /* XXX we'd like to check for a cycle of waiting * LWPs (specific LID waits, not any-LWP waits) * and detect that sort of deadlock, but we don't * have a good place to store the lwp that is * being waited for. wchan is already filled with * &p->p_nlwps, and putting the lwp address in * there for deadlock tracing would require * exiting LWPs to call wakeup on both their * own address and &p->p_nlwps, to get threads * sleeping on any LWP exiting. * * Revisit later. Maybe another auxillary * storage location associated with sleeping * is in order. */ } } if (nfound == 0) return (ESRCH); if ((error = tsleep((caddr_t) &p->p_nlwps, wpri, (lid != 0) ? waitstr1 : waitstr2, 0)) != 0) return (error); goto loop; } int newlwp(struct lwp *l1, struct proc *p2, vaddr_t uaddr, boolean_t inmem, int flags, void *stack, size_t stacksize, void (*func)(void *), void *arg, struct lwp **rnewlwpp) { struct lwp *l2; int s; l2 = pool_get(&lwp_pool, PR_WAITOK); l2->l_stat = LSIDL; l2->l_forw = l2->l_back = NULL; l2->l_proc = p2; memset(&l2->l_startzero, 0, (unsigned) ((caddr_t)&l2->l_endzero - (caddr_t)&l2->l_startzero)); memcpy(&l2->l_startcopy, &l1->l_startcopy, (unsigned) ((caddr_t)&l2->l_endcopy - (caddr_t)&l2->l_startcopy)); #if !defined(MULTIPROCESSOR) /* * In the single-processor case, all processes will always run * on the same CPU. So, initialize the child's CPU to the parent's * now. In the multiprocessor case, the child's CPU will be * initialized in the low-level context switch code when the * process runs. */ KASSERT(l1->l_cpu != NULL); l2->l_cpu = l1->l_cpu; #else /* * zero child's CPU pointer so we don't get trash. */ l2->l_cpu = NULL; #endif /* ! MULTIPROCESSOR */ l2->l_flag = inmem ? L_INMEM : 0; l2->l_flag |= (flags & LWP_DETACHED) ? L_DETACHED : 0; callout_init(&l2->l_tsleep_ch); if (rnewlwpp != NULL) *rnewlwpp = l2; l2->l_addr = (struct user *)uaddr; uvm_lwp_fork(l1, l2, stack, stacksize, func, (arg != NULL) ? arg : l2); simple_lock(&p2->p_lock); l2->l_lid = ++p2->p_nlwpid; LIST_INSERT_HEAD(&p2->p_lwps, l2, l_sibling); p2->p_nlwps++; simple_unlock(&p2->p_lock); /* XXX should be locked differently... */ s = proclist_lock_write(); LIST_INSERT_HEAD(&alllwp, l2, l_list); proclist_unlock_write(s); if (p2->p_emul->e_lwp_fork) (*p2->p_emul->e_lwp_fork)(l1, l2); return (0); } /* * Quit the process. This will call cpu_exit, which will call cpu_switch, * so this can only be used meaningfully if you're willing to switch away. * Calling with l!=curlwp would be weird. */ void lwp_exit(struct lwp *l) { struct proc *p = l->l_proc; int s; DPRINTF(("lwp_exit: %d.%d exiting.\n", p->p_pid, l->l_lid)); DPRINTF((" nlwps: %d nrlwps %d nzlwps: %d\n", p->p_nlwps, p->p_nrlwps, p->p_nzlwps)); if (p->p_emul->e_lwp_exit) (*p->p_emul->e_lwp_exit)(l); /* * If we are the last live LWP in a process, we need to exit * the entire process (if that's not already going on). We do * so with an exit status of zero, because it's a "controlled" * exit, and because that's what Solaris does. */ if (((p->p_nlwps - p->p_nzlwps) == 1) && ((p->p_flag & P_WEXIT) == 0)) { DPRINTF(("lwp_exit: %d.%d calling exit1()\n", p->p_pid, l->l_lid)); exit1(l, 0); /* NOTREACHED */ } s = proclist_lock_write(); LIST_REMOVE(l, l_list); proclist_unlock_write(s); /* Free MD LWP resources */ #ifndef __NO_CPU_LWP_FREE cpu_lwp_free(l, 0); #endif simple_lock(&p->p_lock); p->p_nrlwps--; simple_unlock(&p->p_lock); l->l_stat = LSDEAD; /* This LWP no longer needs to hold the kernel lock. */ KERNEL_PROC_UNLOCK(l); pmap_deactivate(l); /* cpu_exit() will not return */ cpu_exit(l); } /* * We are called from cpu_exit() once it is safe to schedule the * dead process's resources to be freed (i.e., once we've switched to * the idle PCB for the current CPU). * * NOTE: One must be careful with locking in this routine. It's * called from a critical section in machine-dependent code, so * we should refrain from changing any interrupt state. */ void lwp_exit2(struct lwp *l) { struct proc *p; KERNEL_LOCK(LK_EXCLUSIVE); /* * Free the VM resources we're still holding on to. */ uvm_lwp_exit(l); if (l->l_flag & L_DETACHED) { /* Nobody waits for detached LWPs. */ if ((l->l_flag & L_PROCEXIT) == 0) { LIST_REMOVE(l, l_sibling); p = l->l_proc; p->p_nlwps--; } pool_put(&lwp_pool, l); KERNEL_UNLOCK(); } else { l->l_stat = LSZOMB; p = l->l_proc; p->p_nzlwps++; KERNEL_UNLOCK(); wakeup(&p->p_nlwps); } } /* * Pick a LWP to represent the process for those operations which * want information about a "process" that is actually associated * with a LWP. */ struct lwp * proc_representative_lwp(struct proc *p) { struct lwp *l, *onproc, *running, *sleeping, *stopped, *suspended; struct lwp *signalled; /* Trivial case: only one LWP */ if (p->p_nlwps == 1) return (LIST_FIRST(&p->p_lwps)); switch (p->p_stat) { case SSTOP: case SACTIVE: /* Pick the most live LWP */ onproc = running = sleeping = stopped = suspended = NULL; signalled = NULL; LIST_FOREACH(l, &p->p_lwps, l_sibling) { if (l->l_lid == p->p_sigctx.ps_lwp) signalled = l; switch (l->l_stat) { case LSONPROC: onproc = l; break; case LSRUN: running = l; break; case LSSLEEP: sleeping = l; break; case LSSTOP: stopped = l; break; case LSSUSPENDED: suspended = l; break; } } if (signalled) return signalled; if (onproc) return onproc; if (running) return running; if (sleeping) return sleeping; if (stopped) return stopped; if (suspended) return suspended; break; case SZOMB: /* Doesn't really matter... */ return (LIST_FIRST(&p->p_lwps)); #ifdef DIAGNOSTIC case SIDL: /* We have more than one LWP and we're in SIDL? * How'd that happen? */ panic("Too many LWPs (%d) in SIDL process %d (%s)", p->p_nrlwps, p->p_pid, p->p_comm); default: panic("Process %d (%s) in unknown state %d", p->p_pid, p->p_comm, p->p_stat); #endif } panic("proc_representative_lwp: couldn't find a lwp for process" " %d (%s)", p->p_pid, p->p_comm); /* NOTREACHED */ return NULL; }