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Commit 0ae94e00 authored by Paul E. McKenney's avatar Paul E. McKenney
Browse files

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: default avatarPaul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: default avatarNicholas Piggin <npiggin@gmail.com>
parent 51af970d

kernel/rcu/tree.c

+1 −1
Original line number Diff line number Diff line
@@ -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);

}



/*

kernel/rcu/tree.h

+2 −1
Original line number Diff line number Diff line
@@ -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;							\

})