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Date: Tue, 26 Jul 2011 11:17:54 +0000
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Subject: socsvn commit: r224644 - soc2011/rudot/kern
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Author: rudot
Date: Tue Jul 26 11:17:54 2011
New Revision: 224644
URL: http://svnweb.FreeBSD.org/socsvn/?view=rev&rev=224644

Log:
  check if the per-cpu current thread ptr is a valid pointer. If not then do not use it.

Modified:
  soc2011/rudot/kern/sched_fbfs.c

Modified: soc2011/rudot/kern/sched_fbfs.c
==============================================================================
--- soc2011/rudot/kern/sched_fbfs.c	Tue Jul 26 10:50:33 2011	(r224643)
+++ soc2011/rudot/kern/sched_fbfs.c	Tue Jul 26 11:17:54 2011	(r224644)
@@ -149,7 +149,6 @@
 SYSCTL_INT(_kern_sched, OID_AUTO, slice, CTLFLAG_RW, &sched_slice, 0,
 	"Slice size for timeshare threads");
 
-
 static __inline void
 sched_load_add(void)
 {
@@ -613,28 +612,32 @@
 	struct pcpu * pcpu;
 	struct td_sched *ts;
 	struct td_sched *tsc;
+	struct thread *pcpu_thr;
 	u_char c;
 
 	c = td->td_lastcpu;
 	if (c == NOCPU)
 		return (0);
 	pcpu = pcpu_find(c);
-	if (pcpu->pc_curthread == pcpu->pc_idlethread) {
+	pcpu_thr = pcpu->pc_curthread;
+	if (pcpu_thr == NULL)
+		return (0);
+	if (pcpu_thr == pcpu->pc_idlethread) {
 		if (PCPU_GET(cpuid) != c) 
 			ipi_cpu(c, IPI_AST);
 		return (1);
 	}
-	cpri = pcpu->pc_curthread->td_priority;
+	cpri = pcpu_thr->td_priority;
 	if (cpri < td->td_priority)
 		return (0);
 	if (cpri > td->td_priority) {
-		pcpu->pc_curthread->td_flags |= TDF_NEEDRESCHED;
+		pcpu_thr->td_flags |= TDF_NEEDRESCHED;
 		if (PCPU_GET(cpuid) != c) 
 			ipi_cpu(c, IPI_AST);
 		return (1);
 	}
 	ts = td->td_sched;
-	tsc = pcpu->pc_curthread->td_sched;
+	tsc = pcpu_thr->td_sched;
 	if ((td->td_pri_class == PRI_TIMESHARE) ||
 	    (td->td_pri_class == PRI_IDLE)) {
 		if (ts->ts_vdeadline >= tsc->ts_vdeadline)
@@ -647,7 +650,7 @@
 	 * Further, the virtual deadline of td is lower. Therefore we
 	 * reschedule the td_lastcpu.
 	 */
-	pcpu->pc_curthread->td_flags |= TDF_NEEDRESCHED;
+	pcpu_thr->td_flags |= TDF_NEEDRESCHED;
 	if (PCPU_GET(cpuid) != c) 
 		ipi_cpu(c, IPI_AST);
 
@@ -667,6 +670,9 @@
 	ts = max_thread->td_sched;
 	SLIST_FOREACH(pc, &cpuhead, pc_allcpu) {
 		cthr = pc->pc_curthread;
+		if (cthr == NULL) {
+			continue;
+		}
 		if (max_prio < cthr->td_priority) {
 			max_thread = cthr;
 			max_prio = max_thread->td_priority;