This patch uses the rcu_assign_pointer() API to eliminate a number
of explicit memory barriers from code using RCU. This has been
tested successfully on i386 and ppc64.
Signed-off-by: <[email protected]>
---
arch/x86_64/kernel/mce.c | 3 +--
include/linux/list.h | 2 --
net/core/netfilter.c | 3 +--
net/decnet/dn_route.c | 13 +++++--------
net/ipv4/devinet.c | 3 +--
net/ipv4/route.c | 7 +++----
net/sched/sch_api.c | 3 +--
7 files changed, 12 insertions(+), 22 deletions(-)
diff -urpN -X ../dontdiff linux-2.5/arch/x86_64/kernel/mce.c linux-2.5-rap/arch/x86_64/kernel/mce.c
--- linux-2.5/arch/x86_64/kernel/mce.c Tue Sep 7 10:02:15 2004
+++ linux-2.5-rap/arch/x86_64/kernel/mce.c Tue Sep 7 10:29:18 2004
@@ -358,8 +358,7 @@ static ssize_t mce_read(struct file *fil
memset(mcelog.entry, 0, next * sizeof(struct mce));
mcelog.next = 0;
- smp_wmb();
-
+
synchronize_kernel();
/* Collect entries that were still getting written before the synchronize. */
diff -urpN -X ../dontdiff linux-2.5/include/linux/list.h linux-2.5-rap/include/linux/list.h
--- linux-2.5/include/linux/list.h Tue Sep 7 10:04:28 2004
+++ linux-2.5-rap/include/linux/list.h Tue Sep 7 10:42:56 2004
@@ -553,8 +553,6 @@ static inline void hlist_del_init(struct
}
}
-#define hlist_del_rcu_init hlist_del_init
-
static inline void hlist_add_head(struct hlist_node *n, struct hlist_head *h)
{
struct hlist_node *first = h->first;
diff -urpN -X ../dontdiff linux-2.5/net/core/netfilter.c linux-2.5-rap/net/core/netfilter.c
--- linux-2.5/net/core/netfilter.c Tue Sep 7 10:04:41 2004
+++ linux-2.5-rap/net/core/netfilter.c Tue Sep 7 10:29:20 2004
@@ -751,10 +751,9 @@ int nf_log_register(int pf, nf_logfn *lo
/* Any setup of logging members must be done before
* substituting pointer. */
- smp_wmb();
spin_lock(&nf_log_lock);
if (!nf_logging[pf]) {
- nf_logging[pf] = logfn;
+ rcu_assign_pointer(nf_logging[pf], logfn);
ret = 0;
}
spin_unlock(&nf_log_lock);
diff -urpN -X ../dontdiff linux-2.5/net/decnet/dn_route.c linux-2.5-rap/net/decnet/dn_route.c
--- linux-2.5/net/decnet/dn_route.c Tue Sep 7 10:04:41 2004
+++ linux-2.5-rap/net/decnet/dn_route.c Tue Sep 7 10:29:24 2004
@@ -287,10 +287,9 @@ static int dn_insert_route(struct dn_rou
if (compare_keys(&rth->fl, &rt->fl)) {
/* Put it first */
*rthp = rth->u.rt_next;
- smp_wmb();
- rth->u.rt_next = dn_rt_hash_table[hash].chain;
- smp_wmb();
- dn_rt_hash_table[hash].chain = rth;
+ rcu_assign_pointer(rth->u.rt_next,
+ dn_rt_hash_table[hash].chain);
+ rcu_assign_pointer(dn_rt_hash_table[hash].chain, rth);
rth->u.dst.__use++;
dst_hold(&rth->u.dst);
@@ -304,10 +303,8 @@ static int dn_insert_route(struct dn_rou
rthp = &rth->u.rt_next;
}
- smp_wmb();
- rt->u.rt_next = dn_rt_hash_table[hash].chain;
- smp_wmb();
- dn_rt_hash_table[hash].chain = rt;
+ rcu_assign_pointer(rt->u.rt_next, dn_rt_hash_table[hash].chain);
+ rcu_assign_pointer(dn_rt_hash_table[hash].chain, rt);
dst_hold(&rt->u.dst);
rt->u.dst.__use++;
diff -urpN -X ../dontdiff linux-2.5/net/ipv4/devinet.c linux-2.5-rap/net/ipv4/devinet.c
--- linux-2.5/net/ipv4/devinet.c Tue Sep 7 10:04:42 2004
+++ linux-2.5-rap/net/ipv4/devinet.c Tue Sep 7 10:29:25 2004
@@ -158,8 +158,7 @@ struct in_device *inetdev_init(struct ne
/* Account for reference dev->ip_ptr */
in_dev_hold(in_dev);
- smp_wmb();
- dev->ip_ptr = in_dev;
+ rcu_assign_pointer(dev->ip_ptr, in_dev);
#ifdef CONFIG_SYSCTL
devinet_sysctl_register(in_dev, &in_dev->cnf);
diff -urpN -X ../dontdiff linux-2.5/net/ipv4/route.c linux-2.5-rap/net/ipv4/route.c
--- linux-2.5/net/ipv4/route.c Tue Sep 7 10:04:42 2004
+++ linux-2.5-rap/net/ipv4/route.c Tue Sep 7 10:29:27 2004
@@ -793,14 +793,13 @@ restart:
* must be visible to another weakly ordered CPU before
* the insertion at the start of the hash chain.
*/
- smp_wmb();
- rth->u.rt_next = rt_hash_table[hash].chain;
+ rcu_assign_pointer(rth->u.rt_next,
+ rt_hash_table[hash].chain);
/*
* Since lookup is lockfree, the update writes
* must be ordered for consistency on SMP.
*/
- smp_wmb();
- rt_hash_table[hash].chain = rth;
+ rcu_assign_pointer(rt_hash_table[hash].chain, rth);
rth->u.dst.__use++;
dst_hold(&rth->u.dst);
diff -urpN -X ../dontdiff linux-2.5/net/sched/sch_api.c linux-2.5-rap/net/sched/sch_api.c
--- linux-2.5/net/sched/sch_api.c Tue Sep 7 10:04:46 2004
+++ linux-2.5-rap/net/sched/sch_api.c Tue Sep 7 10:29:28 2004
@@ -451,10 +451,9 @@ qdisc_create(struct net_device *dev, u32
/* enqueue is accessed locklessly - make sure it's visible
* before we set a netdevice's qdisc pointer to sch */
- smp_wmb();
if (!ops->init || (err = ops->init(sch, tca[TCA_OPTIONS-1])) == 0) {
qdisc_lock_tree(dev);
- list_add_tail(&sch->list, &dev->qdisc_list);
+ list_add_tail_rcu(&sch->list, &dev->qdisc_list);
qdisc_unlock_tree(dev);
#ifdef CONFIG_NET_ESTIMATOR