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authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2009-08-27 14:58:16 -0700
committerIngo Molnar <mingo@elte.hu>2009-08-29 15:34:39 +0200
commitdd5d19bafd90d33043a4a14b2e2d98612caa293c (patch)
treec21d547124d277f00332bdb01c75f2f4f321de8c /kernel/rcutree.c
parent06e799764eb7c2e4640888d438c3524d756613e1 (diff)
downloadlinux-dd5d19bafd90d33043a4a14b2e2d98612caa293c.tar.bz2
rcu: Create rcutree plugins to handle hotplug CPU for multi-level trees
When offlining CPUs from a multi-level tree, there is the possibility of offlining the last CPU from a given node when there are preempted RCU read-side critical sections that started life on one of the CPUs on that node. In this case, the corresponding tasks will be enqueued via the task_struct's rcu_node_entry list_head onto one of the rcu_node's blocked_tasks[] lists. These tasks need to be moved somewhere else so that they will prevent the current grace period from ending. That somewhere is the root rcu_node. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com> Cc: laijs@cn.fujitsu.com Cc: dipankar@in.ibm.com Cc: akpm@linux-foundation.org Cc: mathieu.desnoyers@polymtl.ca Cc: josht@linux.vnet.ibm.com Cc: dvhltc@us.ibm.com Cc: niv@us.ibm.com Cc: peterz@infradead.org Cc: rostedt@goodmis.org LKML-Reference: <20090827215816.GA30472@linux.vnet.ibm.com> Signed-off-by: Ingo Molnar <mingo@elte.hu>
Diffstat (limited to 'kernel/rcutree.c')
-rw-r--r--kernel/rcutree.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/kernel/rcutree.c b/kernel/rcutree.c
index fee6316a8673..d903e2f2b840 100644
--- a/kernel/rcutree.c
+++ b/kernel/rcutree.c
@@ -81,6 +81,7 @@ struct rcu_state rcu_bh_state = RCU_STATE_INITIALIZER(rcu_bh_state);
DEFINE_PER_CPU(struct rcu_data, rcu_bh_data);
extern long rcu_batches_completed_sched(void);
+static struct rcu_node *rcu_get_root(struct rcu_state *rsp);
static void cpu_quiet_msk(unsigned long mask, struct rcu_state *rsp,
struct rcu_node *rnp, unsigned long flags);
static void cpu_quiet_msk_finish(struct rcu_state *rsp, unsigned long flags);
@@ -876,6 +877,7 @@ static void __rcu_offline_cpu(int cpu, struct rcu_state *rsp)
spin_unlock(&rnp->lock); /* irqs remain disabled. */
break;
}
+ rcu_preempt_offline_tasks(rsp, rnp);
mask = rnp->grpmask;
spin_unlock(&rnp->lock); /* irqs remain disabled. */
rnp = rnp->parent;