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TTY: rfcomm/tty, use tty_port refcounting

Browse Source 
Switch the refcounting from manual atomic plays with refcounter to the
one offered by tty_port.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Jiri Slaby 2012-04-02 13:54:51 +02:00 committed by Greg Kroah-Hartman
parent f60db8c424
commit 6705401928
1 changed files with 26 additions and 32 deletions
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58
net/bluetooth/rfcomm/tty.c
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@ -50,7 +50,6 @@ static struct tty_driver *rfcomm_tty_driver;
struct rfcomm_dev {
struct tty_port port;
struct list_head list;
atomic_t refcnt;
char name[12];
int id;
@ -85,8 +84,17 @@ static void rfcomm_dev_modem_status(struct rfcomm_dlc *dlc, u8 v24_sig);
static void rfcomm_tty_wakeup(struct work_struct *work);
/* ---- Device functions ---- */
static void rfcomm_dev_destruct(struct rfcomm_dev *dev)
/*
* The reason this isn't actually a race, as you no doubt have a little voice
* screaming at you in your head, is that the refcount should never actually
* reach zero unless the device has already been taken off the list, in
* rfcomm_dev_del(). And if that's not true, we'll hit the BUG() in
* rfcomm_dev_destruct() anyway.
*/
static void rfcomm_dev_destruct(struct tty_port *port)
{
struct rfcomm_dev *dev = container_of(port, struct rfcomm_dev, port);
struct rfcomm_dlc *dlc = dev->dlc;
BT_DBG("dev %p dlc %p", dev, dlc);
@ -113,23 +121,9 @@ static void rfcomm_dev_destruct(struct rfcomm_dev *dev)
module_put(THIS_MODULE);
}
static inline void rfcomm_dev_hold(struct rfcomm_dev *dev)
{
atomic_inc(&dev->refcnt);
}
static inline void rfcomm_dev_put(struct rfcomm_dev *dev)
{
/* The reason this isn't actually a race, as you no
doubt have a little voice screaming at you in your
head, is that the refcount should never actually
reach zero unless the device has already been taken
off the list, in rfcomm_dev_del(). And if that's not
true, we'll hit the BUG() in rfcomm_dev_destruct()
anyway. */
if (atomic_dec_and_test(&dev->refcnt))
rfcomm_dev_destruct(dev);
}
static const struct tty_port_operations rfcomm_port_ops = {
.destruct = rfcomm_dev_destruct,
};
static struct rfcomm_dev *__rfcomm_dev_get(int id)
{
@ -154,7 +148,7 @@ static inline struct rfcomm_dev *rfcomm_dev_get(int id)
if (test_bit(RFCOMM_TTY_RELEASED, &dev->flags))
dev = NULL;
else
rfcomm_dev_hold(dev);
tty_port_get(&dev->port);
}
spin_unlock(&rfcomm_dev_lock);
@ -241,7 +235,6 @@ static int rfcomm_dev_add(struct rfcomm_dev_req *req, struct rfcomm_dlc *dlc)
sprintf(dev->name, "rfcomm%d", dev->id);
list_add(&dev->list, head);
atomic_set(&dev->refcnt, 1);
bacpy(&dev->src, &req->src);
bacpy(&dev->dst, &req->dst);
@ -253,6 +246,7 @@ static int rfcomm_dev_add(struct rfcomm_dev_req *req, struct rfcomm_dlc *dlc)
atomic_set(&dev->opened, 0);
tty_port_init(&dev->port);
dev->port.ops = &rfcomm_port_ops;
init_waitqueue_head(&dev->wait);
INIT_WORK(&dev->wakeup_task, rfcomm_tty_wakeup);
@ -332,7 +326,7 @@ static void rfcomm_dev_del(struct rfcomm_dev *dev)
list_del_init(&dev->list);
spin_unlock(&rfcomm_dev_lock);
rfcomm_dev_put(dev);
tty_port_put(&dev->port);
}
/* ---- Send buffer ---- */
@ -349,12 +343,12 @@ static void rfcomm_wfree(struct sk_buff *skb)
atomic_sub(skb->truesize, &dev->wmem_alloc);
if (test_bit(RFCOMM_TTY_ATTACHED, &dev->flags))
queue_work(system_nrt_wq, &dev->wakeup_task);
rfcomm_dev_put(dev);
tty_port_put(&dev->port);
}
static inline void rfcomm_set_owner_w(struct sk_buff *skb, struct rfcomm_dev *dev)
{
rfcomm_dev_hold(dev);
tty_port_get(&dev->port);
atomic_add(skb->truesize, &dev->wmem_alloc);
skb->sk = (void *) dev;
skb->destructor = rfcomm_wfree;
@ -433,7 +427,7 @@ static int rfcomm_release_dev(void __user *arg)
return -ENODEV;
if (dev->flags != NOCAP_FLAGS && !capable(CAP_NET_ADMIN)) {
rfcomm_dev_put(dev);
tty_port_put(&dev->port);
return -EPERM;
}
@ -446,7 +440,7 @@ static int rfcomm_release_dev(void __user *arg)
if (!test_bit(RFCOMM_RELEASE_ONHUP, &dev->flags))
rfcomm_dev_del(dev);
rfcomm_dev_put(dev);
tty_port_put(&dev->port);
return 0;
}
@ -524,7 +518,7 @@ static int rfcomm_get_dev_info(void __user *arg)
if (copy_to_user(arg, &di, sizeof(di)))
err = -EFAULT;
rfcomm_dev_put(dev);
tty_port_put(&dev->port);
return err;
}
@ -592,7 +586,7 @@ static void rfcomm_dev_state_change(struct rfcomm_dlc *dlc, int err)
* 1. rfcomm_dev_get will take rfcomm_dev_lock
* but in rfcomm_dev_add there's lock order:
* rfcomm_dev_lock -> dlc lock
* 2. rfcomm_dev_put will deadlock if it's
* 2. tty_port_put will deadlock if it's
* the last reference
*/
rfcomm_dlc_unlock(dlc);
@ -602,7 +596,7 @@ static void rfcomm_dev_state_change(struct rfcomm_dlc *dlc, int err)
}
rfcomm_dev_del(dev);
rfcomm_dev_put(dev);
tty_port_put(&dev->port);
rfcomm_dlc_lock(dlc);
}
} else
@ -771,11 +765,11 @@ static void rfcomm_tty_close(struct tty_struct *tty, struct file *filp)
list_del_init(&dev->list);
spin_unlock(&rfcomm_dev_lock);
rfcomm_dev_put(dev);
tty_port_put(&dev->port);
}
}
rfcomm_dev_put(dev);
tty_port_put(&dev->port);
}
static int rfcomm_tty_write(struct tty_struct *tty, const unsigned char *buf, int count)
@ -1084,7 +1078,7 @@ static void rfcomm_tty_hangup(struct tty_struct *tty)
if (rfcomm_dev_get(dev->id) == NULL)
return;
rfcomm_dev_del(dev);
rfcomm_dev_put(dev);
tty_port_put(&dev->port);
}
}