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authorIngo Molnar <mingo@elte.hu>2008-07-16 00:29:07 +0200
committerIngo Molnar <mingo@elte.hu>2008-07-16 00:29:07 +0200
commit82638844d9a8581bbf33201cc209a14876eca167 (patch)
tree961d7f9360194421a71aa644a9d0c176a960ce49 /kernel/rcuclassic.c
parent9982fbface82893e77d211fbabfbd229da6bdde6 (diff)
parent63cf13b77ab785e87c867defa8545e6d4a989774 (diff)
Merge branch 'linus' into cpus4096
Conflicts: arch/x86/xen/smp.c kernel/sched_rt.c net/iucv/iucv.c Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/rcuclassic.c')
-rw-r--r--kernel/rcuclassic.c36
1 files changed, 34 insertions, 2 deletions
diff --git a/kernel/rcuclassic.c b/kernel/rcuclassic.c
index adde10388d0c..6f8696c502f4 100644
--- a/kernel/rcuclassic.c
+++ b/kernel/rcuclassic.c
@@ -387,6 +387,10 @@ static void __rcu_offline_cpu(struct rcu_data *this_rdp,
rcu_move_batch(this_rdp, rdp->donelist, rdp->donetail);
rcu_move_batch(this_rdp, rdp->curlist, rdp->curtail);
rcu_move_batch(this_rdp, rdp->nxtlist, rdp->nxttail);
+
+ local_irq_disable();
+ this_rdp->qlen += rdp->qlen;
+ local_irq_enable();
}
static void rcu_offline_cpu(int cpu)
@@ -516,10 +520,38 @@ void rcu_check_callbacks(int cpu, int user)
if (user ||
(idle_cpu(cpu) && !in_softirq() &&
hardirq_count() <= (1 << HARDIRQ_SHIFT))) {
+
+ /*
+ * Get here if this CPU took its interrupt from user
+ * mode or from the idle loop, and if this is not a
+ * nested interrupt. In this case, the CPU is in
+ * a quiescent state, so count it.
+ *
+ * Also do a memory barrier. This is needed to handle
+ * the case where writes from a preempt-disable section
+ * of code get reordered into schedule() by this CPU's
+ * write buffer. The memory barrier makes sure that
+ * the rcu_qsctr_inc() and rcu_bh_qsctr_inc() are see
+ * by other CPUs to happen after any such write.
+ */
+
+ smp_mb(); /* See above block comment. */
rcu_qsctr_inc(cpu);
rcu_bh_qsctr_inc(cpu);
- } else if (!in_softirq())
+
+ } else if (!in_softirq()) {
+
+ /*
+ * Get here if this CPU did not take its interrupt from
+ * softirq, in other words, if it is not interrupting
+ * a rcu_bh read-side critical section. This is an _bh
+ * critical section, so count it. The memory barrier
+ * is needed for the same reason as is the above one.
+ */
+
+ smp_mb(); /* See above block comment. */
rcu_bh_qsctr_inc(cpu);
+ }
raise_rcu_softirq();
}
@@ -543,7 +575,7 @@ static void __cpuinit rcu_online_cpu(int cpu)
rcu_init_percpu_data(cpu, &rcu_ctrlblk, rdp);
rcu_init_percpu_data(cpu, &rcu_bh_ctrlblk, bh_rdp);
- open_softirq(RCU_SOFTIRQ, rcu_process_callbacks, NULL);
+ open_softirq(RCU_SOFTIRQ, rcu_process_callbacks);
}
static int __cpuinit rcu_cpu_notify(struct notifier_block *self,

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