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Date: Thu, 11 Feb 2010 16:45:02 +0100
From: Arnd Bergmann <arnd@...db.de>
To: Patrick McHardy <kaber@...sh.net>
Cc: Sridhar Samudrala <sri@...ibm.com>,
Ed Swierk <eswierk@...stanetworks.com>, netdev@...r.kernel.org
Subject: [PATCH] net/macvtap: fix reference counting
The RCU usage in the original code was broken because
there are cases where we possibly sleep with rcu_read_lock
held. As a fix, change the macvtap_file_get_queue to
get a reference on the socket and the netdev instead of
taking the full rcu_read_lock.
Also, change macvtap_file_get_queue failure case to
not require a subsequent macvtap_file_put_queue, as
pointed out by Ed Swierk.
Signed-off-by: Arnd Bergmann <arnd@...db.de>
Cc: Ed Swierk <eswierk@...stanetworks.com>
Cc: Sridhar Samudrala <sri@...ibm.com>
---
drivers/net/macvtap.c | 57 +++++++++++++++++++++++++++++++-----------------
1 files changed, 37 insertions(+), 20 deletions(-)
Sridhar, Ed: Does this look ok to you? I'm still working
on restoring my test setup, but I'd like you to take a
look at this version.
diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c
index ad1f6ef..5954324 100644
--- a/drivers/net/macvtap.c
+++ b/drivers/net/macvtap.c
@@ -159,8 +159,12 @@ static void macvtap_del_queues(struct net_device *dev)
static inline struct macvtap_queue *macvtap_file_get_queue(struct file *file)
{
+ struct macvtap_queue *q;
rcu_read_lock_bh();
- return rcu_dereference(file->private_data);
+ q = rcu_dereference(file->private_data);
+ if (!q)
+ rcu_read_unlock_bh();
+ return q;
}
static inline void macvtap_file_put_queue(void)
@@ -314,13 +318,13 @@ static unsigned int macvtap_poll(struct file *file, poll_table * wait)
sock_writeable(&q->sk)))
mask |= POLLOUT | POLLWRNORM;
-out:
macvtap_file_put_queue();
+out:
return mask;
}
/* Get packet from user space buffer */
-static ssize_t macvtap_get_user(struct macvtap_queue *q,
+static ssize_t macvtap_get_user(struct macvlan_dev *vlan, struct sock *sk,
const struct iovec *iv, size_t count,
int noblock)
{
@@ -331,10 +335,10 @@ static ssize_t macvtap_get_user(struct macvtap_queue *q,
if (unlikely(len < ETH_HLEN))
return -EINVAL;
- skb = sock_alloc_send_skb(&q->sk, NET_IP_ALIGN + len, noblock, &err);
+ skb = sock_alloc_send_skb(sk, NET_IP_ALIGN + len, noblock, &err);
if (!skb) {
- macvlan_count_rx(q->vlan, 0, false, false);
+ macvlan_count_rx(vlan, 0, false, false);
return err;
}
@@ -342,14 +346,14 @@ static ssize_t macvtap_get_user(struct macvtap_queue *q,
skb_put(skb, count);
if (skb_copy_datagram_from_iovec(skb, 0, iv, 0, len)) {
- macvlan_count_rx(q->vlan, 0, false, false);
+ macvlan_count_rx(vlan, 0, false, false);
kfree_skb(skb);
return -EFAULT;
}
skb_set_network_header(skb, ETH_HLEN);
- macvlan_start_xmit(skb, q->vlan->dev);
+ macvlan_start_xmit(skb, vlan->dev);
return count;
}
@@ -360,23 +364,29 @@ static ssize_t macvtap_aio_write(struct kiocb *iocb, const struct iovec *iv,
struct file *file = iocb->ki_filp;
ssize_t result = -ENOLINK;
struct macvtap_queue *q = macvtap_file_get_queue(file);
+ struct macvlan_dev *vlan;
+ struct sock *sk;
if (!q)
goto out;
- result = macvtap_get_user(q, iv, iov_length(iv, count),
+ vlan = q->vlan;
+ sk = &q->sk;
+ sock_hold(sk);
+ macvtap_file_put_queue();
+
+ result = macvtap_get_user(vlan, sk, iv, iov_length(iv, count),
file->f_flags & O_NONBLOCK);
+ sock_put(sk);
out:
- macvtap_file_put_queue();
return result;
}
/* Put packet to the user space buffer */
-static ssize_t macvtap_put_user(struct macvtap_queue *q,
+static ssize_t macvtap_put_user(struct macvlan_dev *vlan,
const struct sk_buff *skb,
const struct iovec *iv, int len)
{
- struct macvlan_dev *vlan = q->vlan;
int ret;
len = min_t(int, skb->len, len);
@@ -393,15 +403,20 @@ static ssize_t macvtap_aio_read(struct kiocb *iocb, const struct iovec *iv,
{
struct file *file = iocb->ki_filp;
struct macvtap_queue *q = macvtap_file_get_queue(file);
+ struct macvlan_dev *vlan;
+ struct sock *sk;
DECLARE_WAITQUEUE(wait, current);
struct sk_buff *skb;
ssize_t len, ret = 0;
- if (!q) {
- ret = -ENOLINK;
- goto out;
- }
+ if (!q)
+ return -ENOLINK;
+
+ vlan = q->vlan;
+ sk = &q->sk;
+ sock_hold(sk);
+ macvtap_file_put_queue();
len = iov_length(iv, count);
if (len < 0) {
@@ -409,12 +424,12 @@ static ssize_t macvtap_aio_read(struct kiocb *iocb, const struct iovec *iv,
goto out;
}
- add_wait_queue(q->sk.sk_sleep, &wait);
+ add_wait_queue(sk->sk_sleep, &wait);
while (len) {
current->state = TASK_INTERRUPTIBLE;
/* Read frames from the queue */
- skb = skb_dequeue(&q->sk.sk_receive_queue);
+ skb = skb_dequeue(&sk->sk_receive_queue);
if (!skb) {
if (file->f_flags & O_NONBLOCK) {
ret = -EAGAIN;
@@ -428,16 +443,16 @@ static ssize_t macvtap_aio_read(struct kiocb *iocb, const struct iovec *iv,
schedule();
continue;
}
- ret = macvtap_put_user(q, skb, iv, len);
+ ret = macvtap_put_user(vlan, skb, iv, len);
kfree_skb(skb);
break;
}
current->state = TASK_RUNNING;
- remove_wait_queue(q->sk.sk_sleep, &wait);
+ remove_wait_queue(sk->sk_sleep, &wait);
out:
- macvtap_file_put_queue();
+ sock_put(sk);
return ret;
}
@@ -485,6 +500,8 @@ static long macvtap_ioctl(struct file *file, unsigned int cmd,
return -EFAULT;
q = macvtap_file_get_queue(file);
+ if (!q)
+ return -ENOLINK;
q->sk.sk_sndbuf = u;
macvtap_file_put_queue();
return 0;
--
1.6.3.3
--
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