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authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2017-07-19 10:56:46 -0700
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2017-07-25 13:04:50 -0700
commit09efeeee173e9f541b15157d30658cd8b23ec4f3 (patch)
tree05f9ac743eef48f6da68dd5eeb088086b7ffe6d0 /kernel/rcu/tree.c
parentaed4e046863820e6d06ebf7c079e9ad924608edf (diff)
rcu: Move callback-list warning to irq-disable region
After adopting callbacks from a newly offlined CPU, the adopting CPU checks to make sure that its callback list's count is zero only if the list has no callbacks and vice versa. Unfortunately, it does so after enabling interrupts, which means that false positives are possible due to interrupt handlers invoking call_rcu(). Although these false positives are improbable, rcutorture did make it happen once. This commit therefore moves this check to an irq-disabled region of code, thus suppressing the false positive. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'kernel/rcu/tree.c')
-rw-r--r--kernel/rcu/tree.c4
1 files changed, 2 insertions, 2 deletions
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index d330c17c8df4..4b03bddbca3c 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -3869,14 +3869,14 @@ static void rcu_migrate_callbacks(int cpu, struct rcu_state *rsp)
rcu_advance_cbs(rsp, rnp_root, rdp); /* Leverage recent GPs. */
rcu_advance_cbs(rsp, rnp_root, my_rdp); /* Assign GP to pending CBs. */
rcu_segcblist_merge(&my_rdp->cblist, &rdp->cblist);
+ WARN_ON_ONCE(rcu_segcblist_empty(&my_rdp->cblist) !=
+ !rcu_segcblist_n_cbs(&my_rdp->cblist));
raw_spin_unlock_irqrestore_rcu_node(rnp_root, flags);
WARN_ONCE(rcu_segcblist_n_cbs(&rdp->cblist) != 0 ||
!rcu_segcblist_empty(&rdp->cblist),
"rcu_cleanup_dead_cpu: Callbacks on offline CPU %d: qlen=%lu, 1stCB=%p\n",
cpu, rcu_segcblist_n_cbs(&rdp->cblist),
rcu_segcblist_first_cb(&rdp->cblist));
- WARN_ON_ONCE(rcu_segcblist_empty(&my_rdp->cblist) !=
- !rcu_segcblist_n_cbs(&my_rdp->cblist));
}
/*