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authorArnd Bergmann <arnd@arndb.de>2010-02-11 05:55:39 +0000
committerDavid S. Miller <davem@davemloft.net>2010-02-15 21:49:49 -0800
commit564517e804c9c6d4e29c270bfc1517404d27107b (patch)
treef1912327050508a1d2902dbba7cbfcf7d054cd0f
parente9449d85c67127d6f9d01aad8963d567ab02cb96 (diff)
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@arndb.de> Cc: Ed Swierk <eswierk@aristanetworks.com> Cc: Sridhar Samudrala <sri@us.ibm.com> Acked-by: Sridhar Samudrala <sri@us.ibm.com> Acked-by: Ed Swierk <eswierk@aristanetworks.com> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--drivers/net/macvtap.c35
1 files changed, 22 insertions, 13 deletions
diff --git a/drivers/net/macvtap.c b/drivers/net/macvtap.c
index ad1f6ef89308..fe7656bf68c6 100644
--- a/drivers/net/macvtap.c
+++ b/drivers/net/macvtap.c
@@ -70,7 +70,8 @@ static struct cdev macvtap_cdev;
* exists.
*
* The callbacks from macvlan are always done with rcu_read_lock held
- * already, while in the file_operations, we get it ourselves.
+ * already. For calls from file_operations, we use the rcu_read_lock_bh
+ * to get a reference count on the socket and the device.
*
* When destroying a queue, we remove the pointers from the file and
* from the dev and then synchronize_rcu to make sure no thread is
@@ -159,13 +160,21 @@ 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) {
+ sock_hold(&q->sk);
+ dev_hold(q->vlan->dev);
+ }
+ rcu_read_unlock_bh();
+ return q;
}
-static inline void macvtap_file_put_queue(void)
+static inline void macvtap_file_put_queue(struct macvtap_queue *q)
{
- rcu_read_unlock_bh();
+ sock_put(&q->sk);
+ dev_put(q->vlan->dev);
}
/*
@@ -314,8 +323,8 @@ static unsigned int macvtap_poll(struct file *file, poll_table * wait)
sock_writeable(&q->sk)))
mask |= POLLOUT | POLLWRNORM;
+ macvtap_file_put_queue(q);
out:
- macvtap_file_put_queue();
return mask;
}
@@ -366,8 +375,8 @@ static ssize_t macvtap_aio_write(struct kiocb *iocb, const struct iovec *iv,
result = macvtap_get_user(q, iv, iov_length(iv, count),
file->f_flags & O_NONBLOCK);
+ macvtap_file_put_queue(q);
out:
- macvtap_file_put_queue();
return result;
}
@@ -398,10 +407,8 @@ static ssize_t macvtap_aio_read(struct kiocb *iocb, const struct iovec *iv,
struct sk_buff *skb;
ssize_t len, ret = 0;
- if (!q) {
- ret = -ENOLINK;
- goto out;
- }
+ if (!q)
+ return -ENOLINK;
len = iov_length(iv, count);
if (len < 0) {
@@ -437,7 +444,7 @@ static ssize_t macvtap_aio_read(struct kiocb *iocb, const struct iovec *iv,
remove_wait_queue(q->sk.sk_sleep, &wait);
out:
- macvtap_file_put_queue();
+ macvtap_file_put_queue(q);
return ret;
}
@@ -468,7 +475,7 @@ static long macvtap_ioctl(struct file *file, unsigned int cmd,
if (!q)
return -ENOLINK;
memcpy(devname, q->vlan->dev->name, sizeof(devname));
- macvtap_file_put_queue();
+ macvtap_file_put_queue(q);
if (copy_to_user(&ifr->ifr_name, q->vlan->dev->name, IFNAMSIZ) ||
put_user((TUN_TAP_DEV | TUN_NO_PI), &ifr->ifr_flags))
@@ -485,8 +492,10 @@ 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();
+ macvtap_file_put_queue(q);
return 0;
case TUNSETOFFLOAD: