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inetpeer: restore small inet_peer structures

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Addition of rcu_head to struct inet_peer added 16bytes on 64bit arches.

Thats a bit unfortunate, since old size was exactly 64 bytes.

This can be solved, using an union between this rcu_head an four fields,
that are normally used only when a refcount is taken on inet_peer.
rcu_head is used only when refcnt=-1, right before structure freeing.

Add a inet_peer_refcheck() function to check this assertion for a while.

We can bring back SLAB_HWCACHE_ALIGN qualifier in kmem cache creation.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet
2010-06-16 04:52:13 +00:00
committed by David S. Miller
parent fdb93f8ac3
commit 317fe0e6c5
4 changed files with 36 additions and 11 deletions
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31
include/net/inetpeer.h
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@@ -22,11 +22,21 @@ struct inet_peer {
__u32 dtime; /* the time of last use of not
* referenced entries */
atomic_t refcnt;
atomic_t rid; /* Frag reception counter */
atomic_t ip_id_count; /* IP ID for the next packet */
__u32 tcp_ts;
__u32 tcp_ts_stamp;
struct rcu_head rcu;
/*
* Once inet_peer is queued for deletion (refcnt == -1), following fields
* are not available: rid, ip_id_count, tcp_ts, tcp_ts_stamp
* We can share memory with rcu_head to keep inet_peer small
* (less then 64 bytes)
*/
union {
struct {
atomic_t rid; /* Frag reception counter */
atomic_t ip_id_count; /* IP ID for the next packet */
__u32 tcp_ts;
__u32 tcp_ts_stamp;
};
struct rcu_head rcu;
};
};
void inet_initpeers(void) __init;
@@ -37,10 +47,21 @@ struct inet_peer *inet_getpeer(__be32 daddr, int create);
/* can be called from BH context or outside */
extern void inet_putpeer(struct inet_peer *p);
/*
* temporary check to make sure we dont access rid, ip_id_count, tcp_ts,
* tcp_ts_stamp if no refcount is taken on inet_peer
*/
static inline void inet_peer_refcheck(const struct inet_peer *p)
{
WARN_ON_ONCE(atomic_read(&p->refcnt) <= 0);
}
/* can be called with or without local BH being disabled */
static inline __u16 inet_getid(struct inet_peer *p, int more)
{
more++;
inet_peer_refcheck(p);
return atomic_add_return(more, &p->ip_id_count) - more;
}