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authorIngo Molnar <mingo@elte.hu>2008-07-06 14:23:39 +0200
committerIngo Molnar <mingo@elte.hu>2008-07-06 14:23:39 +0200
commit68083e05d72d94f347293d8cc0067050ba904bfa (patch)
tree842e71365bd90866be7add181661a4039d891564 /kernel/rcuclassic.c
parent7baac8b91f9871ba8cb09af84de4ae1d86d07812 (diff)
parentb7279469d66b55119784b8b9529c99c1955fe747 (diff)
Merge commit 'v2.6.26-rc9' into cpus4096
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 251358de70b0..adde10388d0c 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_nr(cpu, cpumask)
smp_send_reschedule(cpu);

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