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Date: Thu, 15 Aug 2013 15:31:06 -0700
From: Pravin B Shelar <pshelar@...ira.com>
To: netdev@...r.kernel.org
Cc: Pravin B Shelar <pshelar@...ira.com>
Subject: [PATCH] netlink: Eliminate kmalloc in netlink dump operation.
Following patch stores struct netlink_callback in netlink_sock
to avoid allocating and freeing it on every netlink dump msg.
Only one dump operation is allowed for a given socket at a time
therefore we can safely convert cb pointer to cb struct inside
netlink_sock.
Signed-off-by: Pravin B Shelar <pshelar@...ira.com>
---
net/netlink/af_netlink.c | 97 ++++++++++++++++++++--------------------------
net/netlink/af_netlink.h | 3 +-
2 files changed, 44 insertions(+), 56 deletions(-)
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 6273772..a17dda1 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -595,7 +595,7 @@ static unsigned int netlink_poll(struct file *file, struct socket *sock,
* for dumps is performed here. A dump is allowed to continue
* if at least half the ring is unused.
*/
- while (nlk->cb != NULL && netlink_dump_space(nlk)) {
+ while (nlk->cb_running && netlink_dump_space(nlk)) {
err = netlink_dump(sk);
if (err < 0) {
sk->sk_err = err;
@@ -802,18 +802,6 @@ static void netlink_ring_set_copied(struct sock *sk, struct sk_buff *skb)
#define netlink_mmap_sendmsg(sk, msg, dst_portid, dst_group, siocb) 0
#endif /* CONFIG_NETLINK_MMAP */
-static void netlink_destroy_callback(struct netlink_callback *cb)
-{
- kfree_skb(cb->skb);
- kfree(cb);
-}
-
-static void netlink_consume_callback(struct netlink_callback *cb)
-{
- consume_skb(cb->skb);
- kfree(cb);
-}
-
static void netlink_skb_destructor(struct sk_buff *skb)
{
#ifdef CONFIG_NETLINK_MMAP
@@ -872,12 +860,12 @@ static void netlink_sock_destruct(struct sock *sk)
{
struct netlink_sock *nlk = nlk_sk(sk);
- if (nlk->cb) {
- if (nlk->cb->done)
- nlk->cb->done(nlk->cb);
+ if (nlk->cb_running) {
+ if (nlk->cb.done)
+ nlk->cb.done(&nlk->cb);
- module_put(nlk->cb->module);
- netlink_destroy_callback(nlk->cb);
+ module_put(nlk->cb.module);
+ kfree_skb(nlk->cb.skb);
}
skb_queue_purge(&sk->sk_receive_queue);
@@ -2350,7 +2338,8 @@ static int netlink_recvmsg(struct kiocb *kiocb, struct socket *sock,
skb_free_datagram(sk, skb);
- if (nlk->cb && atomic_read(&sk->sk_rmem_alloc) <= sk->sk_rcvbuf / 2) {
+ if (nlk->cb_running &&
+ atomic_read(&sk->sk_rmem_alloc) <= sk->sk_rcvbuf / 2) {
ret = netlink_dump(sk);
if (ret) {
sk->sk_err = ret;
@@ -2566,13 +2555,12 @@ static int netlink_dump(struct sock *sk)
int alloc_size;
mutex_lock(nlk->cb_mutex);
-
- cb = nlk->cb;
- if (cb == NULL) {
+ if (!nlk->cb_running) {
err = -EINVAL;
goto errout_skb;
}
+ cb = &nlk->cb;
alloc_size = max_t(int, cb->min_dump_alloc, NLMSG_GOODSIZE);
if (!netlink_rx_is_mmaped(sk) &&
@@ -2610,11 +2598,11 @@ static int netlink_dump(struct sock *sk)
if (cb->done)
cb->done(cb);
- nlk->cb = NULL;
- mutex_unlock(nlk->cb_mutex);
+ nlk->cb_running = false;
+ mutex_unlock(nlk->cb_mutex);
module_put(cb->module);
- netlink_consume_callback(cb);
+ consume_skb(cb->skb);
return 0;
errout_skb:
@@ -2632,59 +2620,51 @@ int __netlink_dump_start(struct sock *ssk, struct sk_buff *skb,
struct netlink_sock *nlk;
int ret;
- cb = kzalloc(sizeof(*cb), GFP_KERNEL);
- if (cb == NULL)
- return -ENOBUFS;
-
/* Memory mapped dump requests need to be copied to avoid looping
* on the pending state in netlink_mmap_sendmsg() while the CB hold
* a reference to the skb.
*/
if (netlink_skb_is_mmaped(skb)) {
skb = skb_copy(skb, GFP_KERNEL);
- if (skb == NULL) {
- kfree(cb);
+ if (skb == NULL)
return -ENOBUFS;
- }
} else
atomic_inc(&skb->users);
- cb->dump = control->dump;
- cb->done = control->done;
- cb->nlh = nlh;
- cb->data = control->data;
- cb->module = control->module;
- cb->min_dump_alloc = control->min_dump_alloc;
- cb->skb = skb;
-
sk = netlink_lookup(sock_net(ssk), ssk->sk_protocol, NETLINK_CB(skb).portid);
if (sk == NULL) {
- netlink_destroy_callback(cb);
- return -ECONNREFUSED;
+ ret = -ECONNREFUSED;
+ goto error_free;
}
- nlk = nlk_sk(sk);
+ nlk = nlk_sk(sk);
mutex_lock(nlk->cb_mutex);
/* A dump is in progress... */
- if (nlk->cb) {
- mutex_unlock(nlk->cb_mutex);
- netlink_destroy_callback(cb);
+ if (nlk->cb_running) {
ret = -EBUSY;
- goto out;
+ goto error_unlock;
}
/* add reference of module which cb->dump belongs to */
- if (!try_module_get(cb->module)) {
- mutex_unlock(nlk->cb_mutex);
- netlink_destroy_callback(cb);
+ if (!try_module_get(control->module)) {
ret = -EPROTONOSUPPORT;
- goto out;
+ goto error_unlock;
}
- nlk->cb = cb;
+ cb = &nlk->cb;
+ memset(cb, 0, sizeof(*cb));
+ cb->dump = control->dump;
+ cb->done = control->done;
+ cb->nlh = nlh;
+ cb->data = control->data;
+ cb->module = control->module;
+ cb->min_dump_alloc = control->min_dump_alloc;
+ cb->skb = skb;
+
+ nlk->cb_running = true;
+
mutex_unlock(nlk->cb_mutex);
ret = netlink_dump(sk);
-out:
sock_put(sk);
if (ret)
@@ -2694,6 +2674,13 @@ out:
* signal not to send ACK even if it was requested.
*/
return -EINTR;
+
+error_unlock:
+ sock_put(sk);
+ mutex_unlock(nlk->cb_mutex);
+error_free:
+ kfree_skb(skb);
+ return ret;
}
EXPORT_SYMBOL(__netlink_dump_start);
@@ -2916,14 +2903,14 @@ static int netlink_seq_show(struct seq_file *seq, void *v)
struct sock *s = v;
struct netlink_sock *nlk = nlk_sk(s);
- seq_printf(seq, "%pK %-3d %-6u %08x %-8d %-8d %pK %-8d %-8d %-8lu\n",
+ seq_printf(seq, "%pK %-3d %-6u %08x %-8d %-8d %d %-8d %-8d %-8lu\n",
s,
s->sk_protocol,
nlk->portid,
nlk->groups ? (u32)nlk->groups[0] : 0,
sk_rmem_alloc_get(s),
sk_wmem_alloc_get(s),
- nlk->cb,
+ nlk->cb_running,
atomic_read(&s->sk_refcnt),
atomic_read(&s->sk_drops),
sock_i_ino(s)
diff --git a/net/netlink/af_netlink.h b/net/netlink/af_netlink.h
index eaa88d1..acbd774 100644
--- a/net/netlink/af_netlink.h
+++ b/net/netlink/af_netlink.h
@@ -32,7 +32,8 @@ struct netlink_sock {
unsigned long *groups;
unsigned long state;
wait_queue_head_t wait;
- struct netlink_callback *cb;
+ bool cb_running;
+ struct netlink_callback cb;
struct mutex *cb_mutex;
struct mutex cb_def_mutex;
void (*netlink_rcv)(struct sk_buff *skb);
--
1.7.1
--
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