netdev
[Top] [All Lists]

Re: RCU : Use call_rcu_bh() in route cache [3/5]

To: Andrew Morton <akpm@xxxxxxxx>
Subject: Re: RCU : Use call_rcu_bh() in route cache [3/5]
From: Dipankar Sarma <dipankar@xxxxxxxxxx>
Date: Sun, 8 Aug 2004 00:50:23 +0530
Cc: Rusty Russell <rusty@xxxxxxxxxxxxxxx>, "Paul E. McKenney" <paulmck@xxxxxxxxxx>, linux-kernel@xxxxxxxxxxxxxxx, Robert Olsson <Robert.Olsson@xxxxxxxxxxx>, netdev@xxxxxxxxxxx
In-reply-to: <20040807191841.GC3936@xxxxxxxxxx>
References: <20040807191536.GA3936@xxxxxxxxxx> <20040807191729.GB3936@xxxxxxxxxx> <20040807191841.GC3936@xxxxxxxxxx>
Reply-to: dipankar@xxxxxxxxxx
Sender: netdev-bounce@xxxxxxxxxxx
User-agent: Mutt/1.4.1i
Use call_rcu_bh() in route cache. This allows faster grace periods and
avoids dst cache overflows during DoS testing.

Thanks
Dipankar


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 <dipankar@xxxxxxxxxx>


 net/decnet/dn_route.c |   28 ++++++++++++++--------------
 net/ipv4/route.c      |   26 +++++++++++++-------------
 2 files changed, 27 insertions(+), 27 deletions(-)

diff -puN net/decnet/dn_route.c~rcu-use-call-rcu-bh net/decnet/dn_route.c
--- linux-2.6.8-rc3-mm1/net/decnet/dn_route.c~rcu-use-call-rcu-bh       
2004-08-07 15:29:16.000000000 +0530
+++ linux-2.6.8-rc3-mm1-dipankar/net/decnet/dn_route.c  2004-08-07 
15:29:16.000000000 +0530
@@ -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 net/ipv4/route.c
--- linux-2.6.8-rc3-mm1/net/ipv4/route.c~rcu-use-call-rcu-bh    2004-08-07 
15:29:16.000000000 +0530
+++ linux-2.6.8-rc3-mm1-dipankar/net/ipv4/route.c       2004-08-07 
15:29:16.000000000 +0530
@@ -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:

_

<Prev in Thread] Current Thread [Next in Thread>