[PATCH 4/4] net,rcu: don't assume the size of struct rcu_head

From: Lai Jiangshan
Date: Tue Mar 01 2011 - 03:02:36 EST



struct dst_entry assumes the size of struct rcu_head as 2 * sizeof(long)
and manually adds pads for aligning for "__refcnt".

When the size of struct rcu_head is changed, these manual padding
is wrong. Use __attribute__((aligned (64))) instead.

Signed-off-by: Lai Jiangshan <laijs@xxxxxxxxxxxxxx>
---
diff --git a/include/net/dst.h b/include/net/dst.h
index 93b0310..4ef6c4a 100644
--- a/include/net/dst.h
+++ b/include/net/dst.h
@@ -62,8 +62,6 @@ struct dst_entry {
struct hh_cache *hh;
#ifdef CONFIG_XFRM
struct xfrm_state *xfrm;
-#else
- void *__pad1;
#endif
int (*input)(struct sk_buff*);
int (*output)(struct sk_buff*);
@@ -74,23 +72,18 @@ struct dst_entry {

#ifdef CONFIG_NET_CLS_ROUTE
__u32 tclassid;
-#else
- __u32 __pad2;
#endif


/*
* Align __refcnt to a 64 bytes alignment
* (L1_CACHE_SIZE would be too much)
- */
-#ifdef CONFIG_64BIT
- long __pad_to_align_refcnt[1];
-#endif
- /*
+ *
* __refcnt wants to be on a different cache line from
* input/output/ops or performance tanks badly
*/
- atomic_t __refcnt; /* client references */
+ atomic_t __refcnt /* client references */
+ __attribute__((aligned (64)));
int __use;
unsigned long lastuse;
union {
--
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