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Date:      Fri, 11 Nov 2011 02:13:35 +0000 (UTC)
From:      Ryan Stone <rstone@FreeBSD.org>
To:        src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-8@freebsd.org
Subject:   svn commit: r227439 - stable/8/sys/kern
Message-ID:  <201111110213.pAB2DZLY066239@svn.freebsd.org>
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Author: rstone
Date: Fri Nov 11 02:13:35 2011
New Revision: 227439
URL: http://svn.freebsd.org/changeset/base/227439

Log:
  MFC 221081:
  
   If the 4BSD scheduler tries to schedule a thread that has been pinned or
   bound to an AP before SMP has started, the system will panic when we try
   to touch per-CPU state for that AP because that state has not been
   initialized yet.  Fix this in the same way as ULE: place all threads in
   the global run queue before SMP has started.

Modified:
  stable/8/sys/kern/sched_4bsd.c
Directory Properties:
  stable/8/sys/   (props changed)
  stable/8/sys/amd64/include/xen/   (props changed)
  stable/8/sys/cddl/contrib/opensolaris/   (props changed)
  stable/8/sys/contrib/dev/acpica/   (props changed)
  stable/8/sys/contrib/pf/   (props changed)

Modified: stable/8/sys/kern/sched_4bsd.c
==============================================================================
--- stable/8/sys/kern/sched_4bsd.c	Fri Nov 11 02:10:24 2011	(r227438)
+++ stable/8/sys/kern/sched_4bsd.c	Fri Nov 11 02:13:35 2011	(r227439)
@@ -1241,25 +1241,27 @@ sched_add(struct thread *td, int flags)
 	}
 	TD_SET_RUNQ(td);
 
-	if (td->td_pinned != 0) {
-		cpu = td->td_lastcpu;
-		ts->ts_runq = &runq_pcpu[cpu];
-		single_cpu = 1;
-		CTR3(KTR_RUNQ,
-		    "sched_add: Put td_sched:%p(td:%p) on cpu%d runq", ts, td,
-		    cpu);
-	} else if (td->td_flags & TDF_BOUND) {
-		/* Find CPU from bound runq. */
-		KASSERT(SKE_RUNQ_PCPU(ts),
-		    ("sched_add: bound td_sched not on cpu runq"));
-		cpu = ts->ts_runq - &runq_pcpu[0];
-		single_cpu = 1;
-		CTR3(KTR_RUNQ,
-		    "sched_add: Put td_sched:%p(td:%p) on cpu%d runq", ts, td,
-		    cpu);
-	} else if (ts->ts_flags & TSF_AFFINITY) {
-		/* Find a valid CPU for our cpuset */
-		cpu = sched_pickcpu(td);
+	/*
+	 * If SMP is started and the thread is pinned or otherwise limited to
+	 * a specific set of CPUs, queue the thread to a per-CPU run queue.
+	 * Otherwise, queue the thread to the global run queue.
+	 *
+	 * If SMP has not yet been started we must use the global run queue
+	 * as per-CPU state may not be initialized yet and we may crash if we
+	 * try to access the per-CPU run queues.
+	 */
+	if (smp_started && (td->td_pinned != 0 || td->td_flags & TDF_BOUND ||
+	    ts->ts_flags & TSF_AFFINITY)) {
+		if (td->td_pinned != 0)
+			cpu = td->td_lastcpu;
+		else if (td->td_flags & TDF_BOUND) {
+			/* Find CPU from bound runq. */
+			KASSERT(SKE_RUNQ_PCPU(ts),
+			    ("sched_add: bound td_sched not on cpu runq"));
+			cpu = ts->ts_runq - &runq_pcpu[0];
+		} else
+			/* Find a valid CPU for our cpuset */
+			cpu = sched_pickcpu(td);
 		ts->ts_runq = &runq_pcpu[cpu];
 		single_cpu = 1;
 		CTR3(KTR_RUNQ,

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