[PATCH tip/core/rcu 07/17] rcu: Loosen __call_rcu()'s rcu_head alignment constraint

[Paul E. McKenney]

From: "Paul E. McKenney" <paulmck@xxxxxxxxxxxxxxxxxx>

The m68k architecture aligns only to 16-bit boundaries, which can cause
the align-to-32-bits check in __call_rcu() to trigger.  Because there is
currently no known potential need for more than one low-order bit, this
commit loosens the check to 16-bit boundaries.

Reported-by: Greg Ungerer <gerg@xxxxxxxxxxx>
Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx>
---
 kernel/rcu/tree.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 6bf7daebcc6b..bcd635e42841 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -2662,7 +2662,7 @@ __call_rcu(struct rcu_head *head, void (*func)(struct rcu_head *rcu),
 	unsigned long flags;
 	struct rcu_data *rdp;
 
-	WARN_ON_ONCE((unsigned long)head & 0x3); /* Misaligned rcu_head! */
+	WARN_ON_ONCE((unsigned long)head & 0x1); /* Misaligned rcu_head! */
 	if (debug_rcu_head_queue(head)) {
 		/* Probable double call_rcu(), so leak the callback. */
 		ACCESS_ONCE(head->func) = rcu_leak_callback;
-- 
1.8.1.5

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