Commit-ID: 0ae94e00ce40e4447080ab7675220f725c690330
Gitweb: https://git.kernel.org/tip/0ae94e00ce40e4447080ab7675220f725c690330
Author: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
AuthorDate: Wed, 18 Apr 2018 14:14:42 -0700
Committer: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
CommitDate: Tue, 15 May 2018 10:29:41 -0700
rcu: Make rcu_future_needs_gp() check all ->need_future_gps[] elements
Currently, the rcu_future_needs_gp() function checks only the current
element of the ->need_future_gps[] array, which might miss elements that
were offset from the expected element, for example, due to races with
the start or the end of a grace period. This commit therefore makes
rcu_future_needs_gp() use the need_any_future_gp() macro to check all
of the elements of this array.
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
Tested-by: Nicholas Piggin <npiggin@xxxxxxxxx>
---
kernel/rcu/tree.c | 2 +-
kernel/rcu/tree.h | 3 ++-
2 files changed, 3 insertions(+), 2 deletions(-)
diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index afc5e32f0da4..b05ab6379562 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -720,7 +720,7 @@ static int rcu_future_needs_gp(struct rcu_state *rsp)
struct rcu_node *rnp = rcu_get_root(rsp);
lockdep_assert_irqs_disabled();
- return READ_ONCE(need_future_gp_element(rnp, rnp->completed));
+ return need_any_future_gp(rnp);
}
/*
diff --git a/kernel/rcu/tree.h b/kernel/rcu/tree.h
index 952cd0c223fe..123c30eac8b5 100644
--- a/kernel/rcu/tree.h
+++ b/kernel/rcu/tree.h
@@ -169,7 +169,8 @@ struct rcu_node {
bool __nonzero = false; \
\
for (__i = 0; __i < ARRAY_SIZE((rnp)->need_future_gp); __i++) \
- __nonzero = __nonzero || (rnp)->need_future_gp[__i]; \
+ __nonzero = __nonzero || \
+ READ_ONCE((rnp)->need_future_gp[__i]); \
__nonzero; \
})
--
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