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authorIngo Molnar <mingo@elte.hu>2008-07-11 10:46:50 +0200
committerIngo Molnar <mingo@elte.hu>2008-07-11 10:46:50 +0200
commit0c81b2a1448bc6a2a9b2d6469fb0669fb4b25e5b (patch)
tree6f82579cae6d6e39fa9f837a3c349ded51e19d14 /kernel/rcuclassic.c
parent0729fbf3bc70870370b4f43d652f05a468dc68b8 (diff)
parent70ff05554f91a1edda1f11684da1dbde09e2feea (diff)
Merge branch 'linus' into core/rcu
Conflicts: include/linux/rculist.h kernel/rcupreempt.c Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/rcuclassic.c')
-rw-r--r--kernel/rcuclassic.c16
1 files changed, 15 insertions, 1 deletions
diff --git a/kernel/rcuclassic.c b/kernel/rcuclassic.c
index d8348792f9f5..214e1cde9812 100644
--- a/kernel/rcuclassic.c
+++ b/kernel/rcuclassic.c
@@ -89,8 +89,22 @@ static void force_quiescent_state(struct rcu_data *rdp,
/*
* Don't send IPI to itself. With irqs disabled,
* rdp->cpu is the current cpu.
+ *
+ * cpu_online_map is updated by the _cpu_down()
+ * using stop_machine_run(). Since we're in irqs disabled
+ * section, stop_machine_run() is not exectuting, hence
+ * the cpu_online_map is stable.
+ *
+ * However, a cpu might have been offlined _just_ before
+ * we disabled irqs while entering here.
+ * And rcu subsystem might not yet have handled the CPU_DEAD
+ * notification, leading to the offlined cpu's bit
+ * being set in the rcp->cpumask.
+ *
+ * Hence cpumask = (rcp->cpumask & cpu_online_map) to prevent
+ * sending smp_reschedule() to an offlined CPU.
*/
- cpumask = rcp->cpumask;
+ cpus_and(cpumask, rcp->cpumask, cpu_online_map);
cpu_clear(rdp->cpu, cpumask);
for_each_cpu_mask(cpu, cpumask)
smp_send_reschedule(cpu);

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