ipv6 flowlabel: Convert hash list to RCU.

Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 54 insertions, 40 deletions

diff --git a/net/ipv6/ip6_flowlabel.c b/net/ipv6/ip6_flowlabel.c
index 5d767f1b8780..da156015d827 100644
--- a/net/ipv6/ip6_flowlabel.c
+++ b/net/ipv6/ip6_flowlabel.c
@@ -51,25 +51,33 @@
 #define FL_HASH(l)      (ntohl(l)&FL_HASH_MASK)
 
 static atomic_t fl_size = ATOMIC_INIT(0);
-static struct ip6_flowlabel *fl_ht[FL_HASH_MASK+1];
+static struct ip6_flowlabel __rcu *fl_ht[FL_HASH_MASK+1];
 
 static void ip6_fl_gc(unsigned long dummy);
 static DEFINE_TIMER(ip6_fl_gc_timer, ip6_fl_gc, 0, 0);
 
 /* FL hash table lock: it protects only of GC */
 
-static DEFINE_RWLOCK(ip6_fl_lock);
+static DEFINE_SPINLOCK(ip6_fl_lock);
 
 /* Big socket sock */
 
 static DEFINE_RWLOCK(ip6_sk_fl_lock);
 
+#define for_each_fl_rcu(hash, fl)                               \
+        for (fl = rcu_dereference(fl_ht[(hash)]);               \
+             fl != NULL;                                        \
+             fl = rcu_dereference(fl->next))
+#define for_each_fl_continue_rcu(fl)                            \
+        for (fl = rcu_dereference(fl->next);                    \
+             fl != NULL;                                        \
+             fl = rcu_dereference(fl->next))
 
 static inline struct ip6_flowlabel *__fl_lookup(struct net *net, __be32 label)
 {
         struct ip6_flowlabel *fl;
 
-        for (fl=fl_ht[FL_HASH(label)]; fl; fl = fl->next) {
+        for_each_fl_rcu(FL_HASH(label), fl) {
                 if (fl->label == label && net_eq(fl->fl_net, net))
                         return fl;
         }
@@ -80,11 +88,11 @@ static struct ip6_flowlabel *fl_lookup(struct net *net, __be32 label)
 {
         struct ip6_flowlabel *fl;
 
-        read_lock_bh(&ip6_fl_lock);
+        rcu_read_lock_bh();
         fl = __fl_lookup(net, label);
-        if (fl)
-                atomic_inc(&fl->users);
-        read_unlock_bh(&ip6_fl_lock);
+        if (fl && !atomic_inc_not_zero(&fl->users))
+                fl = NULL;
+        rcu_read_unlock_bh();
         return fl;
 }
 
@@ -96,13 +104,13 @@ static void fl_free(struct ip6_flowlabel *fl)
                         put_pid(fl->owner.pid);
                 release_net(fl->fl_net);
                 kfree(fl->opt);
+                kfree_rcu(fl, rcu);
         }
-        kfree(fl);
 }
 
 static void fl_release(struct ip6_flowlabel *fl)
 {
-        write_lock_bh(&ip6_fl_lock);
+        spin_lock_bh(&ip6_fl_lock);
 
         fl->lastuse = jiffies;
         if (atomic_dec_and_test(&fl->users)) {
@@ -119,7 +127,7 @@ static void fl_release(struct ip6_flowlabel *fl)
                     time_after(ip6_fl_gc_timer.expires, ttd))
                         mod_timer(&ip6_fl_gc_timer, ttd);
         }
-        write_unlock_bh(&ip6_fl_lock);
+        spin_unlock_bh(&ip6_fl_lock);
 }
 
 static void ip6_fl_gc(unsigned long dummy)
@@ -128,12 +136,13 @@ static void ip6_fl_gc(unsigned long dummy)
         unsigned long now = jiffies;
         unsigned long sched = 0;
 
-        write_lock(&ip6_fl_lock);
+        spin_lock(&ip6_fl_lock);
 
         for (i=0; i<=FL_HASH_MASK; i++) {
                 struct ip6_flowlabel *fl, **flp;
                 flp = &fl_ht[i];
-                while ((fl=*flp) != NULL) {
+                while ((fl = rcu_dereference_protected(*flp,
+                                                       lockdep_is_held(&ip6_fl_lock))) != NULL) {
                         if (atomic_read(&fl->users) == 0) {
                                 unsigned long ttd = fl->lastuse + fl->linger;
                                 if (time_after(ttd, fl->expires))
@@ -156,18 +165,19 @@ static void ip6_fl_gc(unsigned long dummy)
         if (sched) {
                 mod_timer(&ip6_fl_gc_timer, sched);
         }
-        write_unlock(&ip6_fl_lock);
+        spin_unlock(&ip6_fl_lock);
 }
 
 static void __net_exit ip6_fl_purge(struct net *net)
 {
         int i;
 
-        write_lock(&ip6_fl_lock);
+        spin_lock(&ip6_fl_lock);
         for (i = 0; i <= FL_HASH_MASK; i++) {
                 struct ip6_flowlabel *fl, **flp;
                 flp = &fl_ht[i];
-                while ((fl = *flp) != NULL) {
+                while ((fl = rcu_dereference_protected(*flp,
+                                                       lockdep_is_held(&ip6_fl_lock))) != NULL) {
                         if (net_eq(fl->fl_net, net) &&
                             atomic_read(&fl->users) == 0) {
                                 *flp = fl->next;
@@ -178,7 +188,7 @@ static void __net_exit ip6_fl_purge(struct net *net)
                         flp = &fl->next;
                 }
         }
-        write_unlock(&ip6_fl_lock);
+        spin_unlock(&ip6_fl_lock);
 }
 
 static struct ip6_flowlabel *fl_intern(struct net *net,
@@ -188,7 +198,7 @@ static struct ip6_flowlabel *fl_intern(struct net *net,
 
         fl->label = label & IPV6_FLOWLABEL_MASK;
 
-        write_lock_bh(&ip6_fl_lock);
+        spin_lock_bh(&ip6_fl_lock);
         if (label == 0) {
                 for (;;) {
                         fl->label = htonl(net_random())&IPV6_FLOWLABEL_MASK;
@@ -210,16 +220,16 @@ static struct ip6_flowlabel *fl_intern(struct net *net,
                 lfl = __fl_lookup(net, fl->label);
                 if (lfl != NULL) {
                         atomic_inc(&lfl->users);
-                        write_unlock_bh(&ip6_fl_lock);
+                        spin_unlock_bh(&ip6_fl_lock);
                         return lfl;
                 }
         }
 
         fl->lastuse = jiffies;
         fl->next = fl_ht[FL_HASH(fl->label)];
-        fl_ht[FL_HASH(fl->label)] = fl;
+        rcu_assign_pointer(fl_ht[FL_HASH(fl->label)], fl);
         atomic_inc(&fl_size);
-        write_unlock_bh(&ip6_fl_lock);
+        spin_unlock_bh(&ip6_fl_lock);
         return NULL;
 }
 
@@ -650,13 +660,13 @@ static struct ip6_flowlabel *ip6fl_get_first(struct seq_file *seq)
         struct net *net = seq_file_net(seq);
 
         for (state->bucket = 0; state->bucket <= FL_HASH_MASK; ++state->bucket) {
-                fl = fl_ht[state->bucket];
-
-                while (fl && !net_eq(fl->fl_net, net))
-                        fl = fl->next;
-                if (fl)
-                        break;
+                for_each_fl_rcu(state->bucket, fl) {
+                        if (net_eq(fl->fl_net, net))
+                                goto out;
+                }
         }
+        fl = NULL;
+out:
         return fl;
 }
 
@@ -665,18 +675,22 @@ static struct ip6_flowlabel *ip6fl_get_next(struct seq_file *seq, struct ip6_flo
         struct ip6fl_iter_state *state = ip6fl_seq_private(seq);
         struct net *net = seq_file_net(seq);
 
-        fl = fl->next;
+        for_each_fl_continue_rcu(fl) {
+                if (net_eq(fl->fl_net, net))
+                        goto out;
+        }
+
 try_again:
-        while (fl && !net_eq(fl->fl_net, net))
-                fl = fl->next;
-
-        while (!fl) {
-                if (++state->bucket <= FL_HASH_MASK) {
-                        fl = fl_ht[state->bucket];
-                        goto try_again;
-                } else
-                        break;
+        if (++state->bucket <= FL_HASH_MASK) {
+                for_each_fl_rcu(state->bucket, fl) {
+                        if (net_eq(fl->fl_net, net))
+                                goto out;
+                }
+                goto try_again;
         }
+        fl = NULL;
+
+out:
         return fl;
 }
 
@@ -690,9 +704,9 @@ static struct ip6_flowlabel *ip6fl_get_idx(struct seq_file *seq, loff_t pos)
 }
 
 static void *ip6fl_seq_start(struct seq_file *seq, loff_t *pos)
-        __acquires(ip6_fl_lock)
+        __acquires(RCU)
 {
-        read_lock_bh(&ip6_fl_lock);
+        rcu_read_lock_bh();
         return *pos ? ip6fl_get_idx(seq, *pos - 1) : SEQ_START_TOKEN;
 }
 
@@ -709,9 +723,9 @@ static void *ip6fl_seq_next(struct seq_file *seq, void *v, loff_t *pos)
 }
 
 static void ip6fl_seq_stop(struct seq_file *seq, void *v)
-        __releases(ip6_fl_lock)
+        __releases(RCU)
 {
-        read_unlock_bh(&ip6_fl_lock);
+        rcu_read_unlock_bh();
 }
 
 static int ip6fl_seq_show(struct seq_file *seq, void *v)