Actively remove processes from the runqueues of a CPU when we stop it.

Also make sure not to take the scheduler lock once we have stopped a CPU such
that we can safely take it away without having to worry about deadlock
because it happened to own the scheduler lock.

Fixes issues with suspen on SMP machines.

ok mlarkin@, marco@, art@, deraadt@

1 files changed, 22 insertions, 5 deletions

diff --git a/sys/kern/kern_sched.c b/sys/kern/kern_sched.c
index 3bee9d98f0c..82f606fdfe5 100644
--- a/sys/kern/kern_sched.c
+++ b/sys/kern/kern_sched.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: kern_sched.c,v 1.20 2010/05/14 18:47:56 kettenis Exp $	*/
+/*	$OpenBSD: kern_sched.c,v 1.21 2010/05/25 19:59:35 kettenis Exp $	*/
 /*
  * Copyright (c) 2007, 2008 Artur Grabowski <art@openbsd.org>
  *
@@ -42,6 +42,7 @@ struct proc *sched_steal_proc(struct cpu_info *);
  */
 struct cpuset sched_idle_cpus;
 struct cpuset sched_queued_cpus;
+struct cpuset sched_all_cpus;
 
 /*
  * A few notes about cpu_switchto that is implemented in MD code.
@@ -84,6 +85,7 @@ sched_init_cpu(struct cpu_info *ci)
 	 * structures.
 	 */
 	cpuset_init_cpu(ci);
+	cpuset_add(&sched_all_cpus, ci);
 }
 
 void
@@ -147,9 +149,13 @@ sched_idle(void *v)
 		cpuset_add(&sched_idle_cpus, ci);
 		cpu_idle_enter();
 		while (spc->spc_whichqs == 0) {
-			if (spc->spc_schedflags & SPCF_SHOULDHALT) {
+			if (spc->spc_schedflags & SPCF_SHOULDHALT &&
+			    (spc->spc_schedflags & SPCF_HALTED) == 0) {
+				cpuset_del(&sched_idle_cpus, ci);
+				SCHED_LOCK(s);
 				atomic_setbits_int(&spc->spc_schedflags,
-				    SPCF_HALTED);
+				    spc->spc_whichqs ? 0 : SPCF_HALTED);
+				SCHED_UNLOCK(s);
 				wakeup(spc);
 			}
 			cpu_idle_cycle();
@@ -248,6 +254,15 @@ sched_chooseproc(void)
 	SCHED_ASSERT_LOCKED();
 
 	if (spc->spc_schedflags & SPCF_SHOULDHALT) {
+		if (spc->spc_whichqs) {
+			for (queue = 0; queue < SCHED_NQS; queue++) {
+				TAILQ_FOREACH(p, &spc->spc_qs[queue], p_runq) {
+					remrunqueue(p);
+					p->p_cpu = sched_choosecpu(p);
+					setrunqueue(p);
+				}
+			}
+		}
 		p = spc->spc_idleproc;
 		KASSERT(p);
 		p->p_stat = SRUN;
@@ -323,7 +338,7 @@ sched_choosecpu_fork(struct proc *parent, int flags)
 	 */
 	cpuset_complement(&set, &sched_queued_cpus, &sched_idle_cpus);
 	if (cpuset_first(&set) == NULL)
-		cpuset_add_all(&set);
+		cpuset_copy(&set, &sched_all_cpus);
 
 	while ((ci = cpuset_first(&set)) != NULL) {
 		cpuset_del(&set, ci);
@@ -380,7 +395,7 @@ sched_choosecpu(struct proc *p)
 	}
 
 	if (cpuset_first(&set) == NULL)
-		cpuset_add_all(&set);
+		cpuset_copy(&set, &sched_all_cpus);
 
 	while ((ci = cpuset_first(&set)) != NULL) {
 		int cost = sched_proc_to_cpu_cost(ci, p);
@@ -554,6 +569,7 @@ sched_start_secondary_cpus(void)
 
 		if (CPU_IS_PRIMARY(ci))
 			continue;
+		cpuset_add(&sched_all_cpus, ci);
 		atomic_clearbits_int(&spc->spc_schedflags,
 		    SPCF_SHOULDHALT | SPCF_HALTED);
 	}
@@ -573,6 +589,7 @@ sched_stop_secondary_cpus(void)
 
 		if (CPU_IS_PRIMARY(ci))
 			continue;
+		cpuset_del(&sched_all_cpus, ci);
 		atomic_setbits_int(&spc->spc_schedflags, SPCF_SHOULDHALT);
 	}
 	CPU_INFO_FOREACH(cii, ci) {