[PATCH tip/core/rcu 05/20] rcu: Consolidate offline-CPU callback initialization

Paul E. McKenney
2015-03-03T17:43:29Z

Currently, both rcu_cleanup_dead_cpu() and rcu_send_cbs_to_orphanage()
initialize the outgoing CPU's callback list. However, only
rcu_cleanup_dead_cpu() invokes rcu_send_cbs_to_orphanage(), and
it does so unconditionally, which means that only one of these
initializations is required. This commit therefore consolidates the
callback-list initialization with the rest of the callback handling in
rcu_send_cbs_to_orphanage().

Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
---
kernel/rcu/tree.c | 9 +++++----
1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 48d640ca1a05..8e020c59ecfd 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -2256,8 +2256,12 @@ rcu_send_cbs_to_orphanage(int cpu, struct rcu_state *rsp,
rsp->orphan_donetail = rdp->nxttail[RCU_DONE_TAIL];
}

- /* Finally, initialize the rcu_data structure's list to empty. */
+ /*
+ * Finally, initialize the rcu_data structure's list to empty and
+ * disallow further callbacks on this CPU.
+ */
init_callback_list(rdp);
+ rdp->nxttail[RCU_NEXT_TAIL] = NULL;
}

/*
@@ -2398,9 +2402,6 @@ static void rcu_cleanup_dead_cpu(int cpu, struct rcu_state *rsp)
WARN_ONCE(rdp->qlen != 0 || rdp->nxtlist != NULL,
"rcu_cleanup_dead_cpu: Callbacks on offline CPU %d: qlen=%lu, nxtlist=%p\n",
cpu, rdp->qlen, rdp->nxtlist);
- init_callback_list(rdp);
- /* Disallow further callbacks on this CPU. */
- rdp->nxttail[RCU_NEXT_TAIL] = NULL;
mutex_unlock(&rsp->onoff_mutex);
}

--
1.8.1.5