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decnet: RCU conversion and get rid of dev_base_lock

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While tracking dev_base_lock users, I found decnet used it in
dnet_select_source(), but for a wrong purpose:

Writers only hold RTNL, not dev_base_lock, so readers must use RCU if
they cannot use RTNL.

Adds an rcu_head in struct dn_ifaddr and handle proper RCU management.

Adds __rcu annotation in dn_route as well.

Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Acked-by: Steven Whitehouse <swhiteho@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet
2010-10-29 03:09:24 +00:00
committed by David S. Miller
parent e4a7b93bd5
commit fc766e4c49
8 changed files with 127 additions and 88 deletions
Download Patch File Download Diff File Expand all files Collapse all files

68
net/decnet/dn_route.c
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@@ -93,7 +93,7 @@
struct dn_rt_hash_bucket
{
struct dn_route *chain;
struct dn_route __rcu *chain;
spinlock_t lock;
};
@@ -157,15 +157,17 @@ static inline void dnrt_drop(struct dn_route *rt)
static void dn_dst_check_expire(unsigned long dummy)
{
int i;
struct dn_route *rt, **rtp;
struct dn_route *rt;
struct dn_route __rcu **rtp;
unsigned long now = jiffies;
unsigned long expire = 120 * HZ;
for(i = 0; i <= dn_rt_hash_mask; i++) {
for (i = 0; i <= dn_rt_hash_mask; i++) {
rtp = &dn_rt_hash_table[i].chain;
spin_lock(&dn_rt_hash_table[i].lock);
while((rt=*rtp) != NULL) {
while ((rt = rcu_dereference_protected(*rtp,
lockdep_is_held(&dn_rt_hash_table[i].lock))) != NULL) {
if (atomic_read(&rt->dst.__refcnt) ||
(now - rt->dst.lastuse) < expire) {
rtp = &rt->dst.dn_next;
@@ -186,17 +188,19 @@ static void dn_dst_check_expire(unsigned long dummy)
static int dn_dst_gc(struct dst_ops *ops)
{
struct dn_route *rt, **rtp;
struct dn_route *rt;
struct dn_route __rcu **rtp;
int i;
unsigned long now = jiffies;
unsigned long expire = 10 * HZ;
for(i = 0; i <= dn_rt_hash_mask; i++) {
for (i = 0; i <= dn_rt_hash_mask; i++) {
spin_lock_bh(&dn_rt_hash_table[i].lock);
rtp = &dn_rt_hash_table[i].chain;
while((rt=*rtp) != NULL) {
while ((rt = rcu_dereference_protected(*rtp,
lockdep_is_held(&dn_rt_hash_table[i].lock))) != NULL) {
if (atomic_read(&rt->dst.__refcnt) ||
(now - rt->dst.lastuse) < expire) {
rtp = &rt->dst.dn_next;
@@ -227,7 +231,7 @@ static void dn_dst_update_pmtu(struct dst_entry *dst, u32 mtu)
{
u32 min_mtu = 230;
struct dn_dev *dn = dst->neighbour ?
(struct dn_dev *)dst->neighbour->dev->dn_ptr : NULL;
rcu_dereference_raw(dst->neighbour->dev->dn_ptr) : NULL;
if (dn && dn->use_long == 0)
min_mtu -= 6;
@@ -277,13 +281,15 @@ static inline int compare_keys(struct flowi *fl1, struct flowi *fl2)
static int dn_insert_route(struct dn_route *rt, unsigned hash, struct dn_route **rp)
{
struct dn_route *rth, **rthp;
struct dn_route *rth;
struct dn_route __rcu **rthp;
unsigned long now = jiffies;
rthp = &dn_rt_hash_table[hash].chain;
spin_lock_bh(&dn_rt_hash_table[hash].lock);
while((rth = *rthp) != NULL) {
while ((rth = rcu_dereference_protected(*rthp,
lockdep_is_held(&dn_rt_hash_table[hash].lock))) != NULL) {
if (compare_keys(&rth->fl, &rt->fl)) {
/* Put it first */
*rthp = rth->dst.dn_next;
@@ -315,15 +321,15 @@ static void dn_run_flush(unsigned long dummy)
int i;
struct dn_route *rt, *next;
for(i = 0; i < dn_rt_hash_mask; i++) {
for (i = 0; i < dn_rt_hash_mask; i++) {
spin_lock_bh(&dn_rt_hash_table[i].lock);
if ((rt = xchg(&dn_rt_hash_table[i].chain, NULL)) == NULL)
if ((rt = xchg((struct dn_route **)&dn_rt_hash_table[i].chain, NULL)) == NULL)
goto nothing_to_declare;
for(; rt; rt=next) {
next = rt->dst.dn_next;
rt->dst.dn_next = NULL;
for(; rt; rt = next) {
next = rcu_dereference_raw(rt->dst.dn_next);
RCU_INIT_POINTER(rt->dst.dn_next, NULL);
dst_free((struct dst_entry *)rt);
}
@@ -458,15 +464,16 @@ static int dn_return_long(struct sk_buff *skb)
*/
static int dn_route_rx_packet(struct sk_buff *skb)
{
struct dn_skb_cb *cb = DN_SKB_CB(skb);
struct dn_skb_cb *cb;
int err;
if ((err = dn_route_input(skb)) == 0)
return dst_input(skb);
cb = DN_SKB_CB(skb);
if (decnet_debug_level & 4) {
char *devname = skb->dev ? skb->dev->name : "???";
struct dn_skb_cb *cb = DN_SKB_CB(skb);
printk(KERN_DEBUG
"DECnet: dn_route_rx_packet: rt_flags=0x%02x dev=%s len=%d src=0x%04hx dst=0x%04hx err=%d type=%d\n",
(int)cb->rt_flags, devname, skb->len,
@@ -573,7 +580,7 @@ int dn_route_rcv(struct sk_buff *skb, struct net_device *dev, struct packet_type
struct dn_skb_cb *cb;
unsigned char flags = 0;
__u16 len = le16_to_cpu(*(__le16 *)skb->data);
struct dn_dev *dn = (struct dn_dev *)dev->dn_ptr;
struct dn_dev *dn = rcu_dereference(dev->dn_ptr);
unsigned char padlen = 0;
if (!net_eq(dev_net(dev), &init_net))
@@ -728,7 +735,7 @@ static int dn_forward(struct sk_buff *skb)
{
struct dn_skb_cb *cb = DN_SKB_CB(skb);
struct dst_entry *dst = skb_dst(skb);
struct dn_dev *dn_db = dst->dev->dn_ptr;
struct dn_dev *dn_db = rcu_dereference(dst->dev->dn_ptr);
struct dn_route *rt;
struct neighbour *neigh = dst->neighbour;
int header_len;
@@ -835,13 +842,16 @@ static inline int dn_match_addr(__le16 addr1, __le16 addr2)
static __le16 dnet_select_source(const struct net_device *dev, __le16 daddr, int scope)
{
__le16 saddr = 0;
struct dn_dev *dn_db = dev->dn_ptr;
struct dn_dev *dn_db;
struct dn_ifaddr *ifa;
int best_match = 0;
int ret;
read_lock(&dev_base_lock);
for(ifa = dn_db->ifa_list; ifa; ifa = ifa->ifa_next) {
rcu_read_lock();
dn_db = rcu_dereference(dev->dn_ptr);
for (ifa = rcu_dereference(dn_db->ifa_list);
ifa != NULL;
ifa = rcu_dereference(ifa->ifa_next)) {
if (ifa->ifa_scope > scope)
continue;
if (!daddr) {
@@ -854,7 +864,7 @@ static __le16 dnet_select_source(const struct net_device *dev, __le16 daddr, int
if (best_match == 0)
saddr = ifa->ifa_local;
}
read_unlock(&dev_base_lock);
rcu_read_unlock();
return saddr;
}
@@ -1020,7 +1030,7 @@ source_ok:
err = -ENODEV;
if (dev_out == NULL)
goto out;
dn_db = dev_out->dn_ptr;
dn_db = rcu_dereference_raw(dev_out->dn_ptr);
/* Possible improvement - check all devices for local addr */
if (dn_dev_islocal(dev_out, fl.fld_dst)) {
dev_put(dev_out);
@@ -1233,7 +1243,7 @@ static int dn_route_input_slow(struct sk_buff *skb)
dev_hold(in_dev);
if ((dn_db = in_dev->dn_ptr) == NULL)
if ((dn_db = rcu_dereference(in_dev->dn_ptr)) == NULL)
goto out;
/* Zero source addresses are not allowed */
@@ -1677,15 +1687,15 @@ static struct dn_route *dn_rt_cache_get_next(struct seq_file *seq, struct dn_rou
{
struct dn_rt_cache_iter_state *s = seq->private;
rt = rt->dst.dn_next;
while(!rt) {
rt = rcu_dereference_bh(rt->dst.dn_next);
while (!rt) {
rcu_read_unlock_bh();
if (--s->bucket < 0)
break;
rcu_read_lock_bh();
rt = dn_rt_hash_table[s->bucket].chain;
rt = rcu_dereference_bh(dn_rt_hash_table[s->bucket].chain);
}
return rcu_dereference_bh(rt);
return rt;
}
static void *dn_rt_cache_seq_start(struct seq_file *seq, loff_t *pos)