rcu: Loosen __call_rcu()'s rcu_head alignment constraint

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@uclinux.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Reviewed-by: Lai Jiangshan <laijs@cn.fujitsu.com>

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 6bf7daebcc6b6c9b090998ca7ba9348ba12ce71e..bcd635e42841e219f2e0e557f962a287a2df3558 100644 (file)
--- 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;