From: Dipankar Sarma Use call_rcu_bh() in route cache. This allows faster grace periods and avoids dst cache overflows during DoS testing. This patch uses the call_rcu_bh() api in route cache code to facilitate quicker RCU grace periods. Quicker grace periods avoid overflow of dst cache in heavily loaded routers as seen in Robert Olsson's testing. Signed-off-by: Dipankar Sarma Signed-off-by: Andrew Morton --- 25-akpm/net/decnet/dn_route.c | 28 ++++++++++++++-------------- 25-akpm/net/ipv4/route.c | 26 +++++++++++++------------- 2 files changed, 27 insertions(+), 27 deletions(-) diff -puN net/decnet/dn_route.c~rcu-use-call_rcu_bh-in-route-cache net/decnet/dn_route.c --- 25/net/decnet/dn_route.c~rcu-use-call_rcu_bh-in-route-cache Fri Aug 6 15:13:59 2004 +++ 25-akpm/net/decnet/dn_route.c Fri Aug 6 15:13:59 2004 @@ -146,14 +146,14 @@ static __inline__ unsigned dn_hash(unsig static inline void dnrt_free(struct dn_route *rt) { - call_rcu(&rt->u.dst.rcu_head, dst_rcu_free); + call_rcu_bh(&rt->u.dst.rcu_head, dst_rcu_free); } static inline void dnrt_drop(struct dn_route *rt) { if (rt) dst_release(&rt->u.dst); - call_rcu(&rt->u.dst.rcu_head, dst_rcu_free); + call_rcu_bh(&rt->u.dst.rcu_head, dst_rcu_free); } static void dn_dst_check_expire(unsigned long dummy) @@ -1174,9 +1174,9 @@ static int __dn_route_output_key(struct struct dn_route *rt = NULL; if (!(flags & MSG_TRYHARD)) { - rcu_read_lock(); + rcu_read_lock_bh(); for(rt = dn_rt_hash_table[hash].chain; rt; rt = rt->u.rt_next) { - read_barrier_depends(); + smp_read_barrier_depends(); if ((flp->fld_dst == rt->fl.fld_dst) && (flp->fld_src == rt->fl.fld_src) && #ifdef CONFIG_DECNET_ROUTE_FWMARK @@ -1187,12 +1187,12 @@ static int __dn_route_output_key(struct rt->u.dst.lastuse = jiffies; dst_hold(&rt->u.dst); rt->u.dst.__use++; - rcu_read_unlock(); + rcu_read_unlock_bh(); *pprt = &rt->u.dst; return 0; } } - rcu_read_unlock(); + rcu_read_unlock_bh(); } return dn_route_output_slow(pprt, flp, flags); @@ -1647,21 +1647,21 @@ int dn_cache_dump(struct sk_buff *skb, s continue; if (h > s_h) s_idx = 0; - rcu_read_lock(); + rcu_read_lock_bh(); for(rt = dn_rt_hash_table[h].chain, idx = 0; rt; rt = rt->u.rt_next, idx++) { - read_barrier_depends(); + smp_read_barrier_depends(); if (idx < s_idx) continue; skb->dst = dst_clone(&rt->u.dst); if (dn_rt_fill_info(skb, NETLINK_CB(cb->skb).pid, cb->nlh->nlmsg_seq, RTM_NEWROUTE, 1) <= 0) { dst_release(xchg(&skb->dst, NULL)); - rcu_read_unlock(); + rcu_read_unlock_bh(); goto done; } dst_release(xchg(&skb->dst, NULL)); } - rcu_read_unlock(); + rcu_read_unlock_bh(); } done: @@ -1681,7 +1681,7 @@ static struct dn_route *dn_rt_cache_get_ struct dn_rt_cache_iter_state *s = seq->private; for(s->bucket = dn_rt_hash_mask; s->bucket >= 0; --s->bucket) { - rcu_read_lock(); + rcu_read_lock_bh(); rt = dn_rt_hash_table[s->bucket].chain; if (rt) break; @@ -1697,10 +1697,10 @@ static struct dn_route *dn_rt_cache_get_ smp_read_barrier_depends(); rt = rt->u.rt_next; while(!rt) { - rcu_read_unlock(); + rcu_read_unlock_bh(); if (--s->bucket < 0) break; - rcu_read_lock(); + rcu_read_lock_bh(); rt = dn_rt_hash_table[s->bucket].chain; } return rt; @@ -1727,7 +1727,7 @@ static void *dn_rt_cache_seq_next(struct static void dn_rt_cache_seq_stop(struct seq_file *seq, void *v) { if (v) - rcu_read_unlock(); + rcu_read_unlock_bh(); } static int dn_rt_cache_seq_show(struct seq_file *seq, void *v) diff -puN net/ipv4/route.c~rcu-use-call_rcu_bh-in-route-cache net/ipv4/route.c --- 25/net/ipv4/route.c~rcu-use-call_rcu_bh-in-route-cache Fri Aug 6 15:13:59 2004 +++ 25-akpm/net/ipv4/route.c Fri Aug 6 15:13:59 2004 @@ -226,11 +226,11 @@ static struct rtable *rt_cache_get_first struct rt_cache_iter_state *st = seq->private; for (st->bucket = rt_hash_mask; st->bucket >= 0; --st->bucket) { - rcu_read_lock(); + rcu_read_lock_bh(); r = rt_hash_table[st->bucket].chain; if (r) break; - rcu_read_unlock(); + rcu_read_unlock_bh(); } return r; } @@ -242,10 +242,10 @@ static struct rtable *rt_cache_get_next( smp_read_barrier_depends(); r = r->u.rt_next; while (!r) { - rcu_read_unlock(); + rcu_read_unlock_bh(); if (--st->bucket < 0) break; - rcu_read_lock(); + rcu_read_lock_bh(); r = rt_hash_table[st->bucket].chain; } return r; @@ -281,7 +281,7 @@ static void *rt_cache_seq_next(struct se static void rt_cache_seq_stop(struct seq_file *seq, void *v) { if (v && v != SEQ_START_TOKEN) - rcu_read_unlock(); + rcu_read_unlock_bh(); } static int rt_cache_seq_show(struct seq_file *seq, void *v) @@ -439,13 +439,13 @@ static struct file_operations rt_cpu_seq static __inline__ void rt_free(struct rtable *rt) { - call_rcu(&rt->u.dst.rcu_head, dst_rcu_free); + call_rcu_bh(&rt->u.dst.rcu_head, dst_rcu_free); } static __inline__ void rt_drop(struct rtable *rt) { ip_rt_put(rt); - call_rcu(&rt->u.dst.rcu_head, dst_rcu_free); + call_rcu_bh(&rt->u.dst.rcu_head, dst_rcu_free); } static __inline__ int rt_fast_clean(struct rtable *rth) @@ -2231,7 +2231,7 @@ int __ip_route_output_key(struct rtable hash = rt_hash_code(flp->fl4_dst, flp->fl4_src ^ (flp->oif << 5), flp->fl4_tos); - rcu_read_lock(); + rcu_read_lock_bh(); for (rth = rt_hash_table[hash].chain; rth; rth = rth->u.rt_next) { smp_read_barrier_depends(); if (rth->fl.fl4_dst == flp->fl4_dst && @@ -2247,13 +2247,13 @@ int __ip_route_output_key(struct rtable dst_hold(&rth->u.dst); rth->u.dst.__use++; RT_CACHE_STAT_INC(out_hit); - rcu_read_unlock(); + rcu_read_unlock_bh(); *rp = rth; return 0; } RT_CACHE_STAT_INC(out_hlist_search); } - rcu_read_unlock(); + rcu_read_unlock_bh(); return ip_route_output_slow(rp, flp); } @@ -2463,7 +2463,7 @@ int ip_rt_dump(struct sk_buff *skb, str if (h < s_h) continue; if (h > s_h) s_idx = 0; - rcu_read_lock(); + rcu_read_lock_bh(); for (rt = rt_hash_table[h].chain, idx = 0; rt; rt = rt->u.rt_next, idx++) { smp_read_barrier_depends(); @@ -2474,12 +2474,12 @@ int ip_rt_dump(struct sk_buff *skb, str cb->nlh->nlmsg_seq, RTM_NEWROUTE, 1) <= 0) { dst_release(xchg(&skb->dst, NULL)); - rcu_read_unlock(); + rcu_read_unlock_bh(); goto done; } dst_release(xchg(&skb->dst, NULL)); } - rcu_read_unlock(); + rcu_read_unlock_bh(); } done: _