Hello,
This is a second version of the previous patches I sent to linux-bluetooth
list. I grouped the two patches together since they are related.
I fixed some bugs in my previous attempt:
1. skb_queue_purge is now called in the cleanup method to avoid a circular
dependency between the dev struct and dlc struct.
2. refcomm_dev_release should check REFCOMM_TTY_RELEASED instead of
REFCOMM_RELEASE_ONHUP.
I checked with both bluez4 and bluez5 and everything works as expected.
The patch still depends on the tty_port patch I already sent to linux-kernel
and to its maintainer but I haven't received any reply yet.
Signed-off-by: Gianluca Anzolin <gianluca@xxxxxxxxxxxxxx>
diff --git a/net/bluetooth/rfcomm/tty.c b/net/bluetooth/rfcomm/tty.c
index b6e44ad..d363c56 100644
--- a/net/bluetooth/rfcomm/tty.c
+++ b/net/bluetooth/rfcomm/tty.c
@@ -77,43 +77,143 @@ static void rfcomm_dev_modem_status(struct rfcomm_dlc *dlc, u8 v24_sig);
/* ---- Device functions ---- */
/*
- * 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.
+ * rfcomm_dev_destruct is called when the tty_port refcount reaches zero
*/
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);
+ BT_DBG("destruct dev %p dlc %p", dev, dlc);
- /* Refcount should only hit zero when called from rfcomm_dev_del()
- which will have taken us off the list. Everything else are
- refcounting bugs. */
- BUG_ON(!list_empty(&dev->list));
+ tty_unregister_device(rfcomm_tty_driver, dev->id);
+
+ /* remove the dev from the list */
+ spin_lock(&rfcomm_dev_lock);
+ list_del_init(&dev->list);
+ spin_unlock(&rfcomm_dev_lock);
+ /* reset the DLC owner */
rfcomm_dlc_lock(dlc);
- /* Detach DLC if it's owned by this dev */
if (dlc->owner == dev)
dlc->owner = NULL;
rfcomm_dlc_unlock(dlc);
- rfcomm_dlc_put(dlc);
-
- tty_unregister_device(rfcomm_tty_driver, dev->id);
-
kfree(dev);
-
/* It's safe to call module_put() here because socket still
holds reference to this module. */
module_put(THIS_MODULE);
+
+ rfcomm_dlc_put(dlc);
+}
+
+static struct device *rfcomm_get_device(struct rfcomm_dev *dev)
+{
+ struct hci_dev *hdev;
+ struct hci_conn *conn;
+
+ hdev = hci_get_route(&dev->dst, &dev->src);
+ if (!hdev)
+ return NULL;
+
+ conn = hci_conn_hash_lookup_ba(hdev, ACL_LINK, &dev->dst);
+
+ hci_dev_put(hdev);
+
+ return conn ? &conn->dev : NULL;
+}
+
+static void rfcomm_tty_copy_pending(struct rfcomm_dev *dev)
+{
+ struct sk_buff *skb;
+ int inserted = 0;
+
+ BT_DBG("dev %p", dev);
+
+ rfcomm_dlc_lock(dev->dlc);
+ while ((skb = skb_dequeue(&dev->pending))) {
+ inserted += tty_insert_flip_string(&dev->port, skb->data,
+ skb->len);
+ kfree_skb(skb);
+ }
+
+ rfcomm_dlc_unlock(dev->dlc);
+
+ if (inserted > 0)
+ tty_flip_buffer_push(&dev->port);
+}
+
+static int rfcomm_dev_activate(struct tty_port *port, struct tty_struct *tty)
+{
+ DEFINE_WAIT(wait);
+ struct rfcomm_dev *dev = container_of(port, struct rfcomm_dev, port);
+ struct rfcomm_dlc *dlc = dev->dlc;
+ int err;
+
+ BT_DBG("activate dev %p dst %pMR channel %d opened %d", dev, &dev->dst,
+ dev->channel, dev->port.count);
+
+ err = rfcomm_dlc_open(dlc, &dev->src, &dev->dst, dev->channel);
+ if (err < 0)
+ goto error_no_dlc_open;
+
+ /* Wait for DLC to connect */
+ while (1) {
+ prepare_to_wait(&dev->wait, &wait, TASK_INTERRUPTIBLE);
+
+ if (dlc->state == BT_CLOSED) {
+ err = -dev->err;
+ break;
+ }
+
+ if (dlc->state == BT_CONNECTED)
+ break;
+
+ if (signal_pending(current)) {
+ err = -EINTR;
+ break;
+ }
+
+ tty_unlock(tty);
+ schedule();
+ tty_lock(tty);
+ }
+ finish_wait(&dev->wait, &wait);
+
+ if (err < 0)
+ goto error_no_dlc_connect;
+
+ device_move(dev->tty_dev, rfcomm_get_device(dev),
+ DPM_ORDER_DEV_AFTER_PARENT);
+
+ rfcomm_tty_copy_pending(dev);
+ rfcomm_dlc_unthrottle(dev->dlc);
+
+ return err;
+
+error_no_dlc_connect:
+ rfcomm_dlc_close(dlc, 0);
+error_no_dlc_open:
+ return err;
+}
+
+static void rfcomm_dev_shutdown(struct tty_port *port)
+{
+ struct rfcomm_dev *dev = container_of(port, struct rfcomm_dev, port);
+
+ BT_DBG("shutdown dev %p", dev);
+
+ if (dev->tty_dev->parent)
+ device_move(dev->tty_dev, NULL, DPM_ORDER_DEV_LAST);
+
+ /* Close DLC */
+ rfcomm_dlc_close(dev->dlc, 0);
}
static const struct tty_port_operations rfcomm_port_ops = {
.destruct = rfcomm_dev_destruct,
+ .activate = rfcomm_dev_activate,
+ .shutdown = rfcomm_dev_shutdown,
};
static struct rfcomm_dev *__rfcomm_dev_get(int id)
@@ -147,22 +247,6 @@ static struct rfcomm_dev *rfcomm_dev_get(int id)
return dev;
}
-static struct device *rfcomm_get_device(struct rfcomm_dev *dev)
-{
- struct hci_dev *hdev;
- struct hci_conn *conn;
-
- hdev = hci_get_route(&dev->dst, &dev->src);
- if (!hdev)
- return NULL;
-
- conn = hci_conn_hash_lookup_ba(hdev, ACL_LINK, &dev->dst);
-
- hci_dev_put(hdev);
-
- return conn ? &conn->dev : NULL;
-}
-
static ssize_t show_address(struct device *tty_dev, struct device_attribute *attr, char *buf)
{
struct rfcomm_dev *dev = dev_get_drvdata(tty_dev);
@@ -184,7 +268,7 @@ static int rfcomm_dev_add(struct rfcomm_dev_req *req, struct rfcomm_dlc *dlc)
struct list_head *head = &rfcomm_dev_list;
int err = 0;
- BT_DBG("id %d channel %d", req->dev_id, req->channel);
+ BT_DBG("add dev id %d channel %d", req->dev_id, req->channel);
dev = kzalloc(sizeof(struct rfcomm_dev), GFP_KERNEL);
if (!dev)
@@ -298,30 +382,10 @@ out:
free:
kfree(dev);
+ module_put(THIS_MODULE);
return err;
}
-static void rfcomm_dev_del(struct rfcomm_dev *dev)
-{
- unsigned long flags;
- BT_DBG("dev %p", dev);
-
- BUG_ON(test_and_set_bit(RFCOMM_TTY_RELEASED, &dev->flags));
-
- spin_lock_irqsave(&dev->port.lock, flags);
- if (dev->port.count > 0) {
- spin_unlock_irqrestore(&dev->port.lock, flags);
- return;
- }
- spin_unlock_irqrestore(&dev->port.lock, flags);
-
- spin_lock(&rfcomm_dev_lock);
- list_del_init(&dev->list);
- spin_unlock(&rfcomm_dev_lock);
-
- tty_port_put(&dev->port);
-}
-
/* ---- Send buffer ---- */
static inline unsigned int rfcomm_room(struct rfcomm_dlc *dlc)
{
@@ -333,10 +397,11 @@ static inline unsigned int rfcomm_room(struct rfcomm_dlc *dlc)
static void rfcomm_wfree(struct sk_buff *skb)
{
struct rfcomm_dev *dev = (void *) skb->sk;
- struct tty_struct *tty = dev->port.tty;
+
atomic_sub(skb->truesize, &dev->wmem_alloc);
- if (test_bit(RFCOMM_TTY_ATTACHED, &dev->flags) && tty)
- tty_wakeup(tty);
+ if (test_bit(RFCOMM_TTY_ATTACHED, &dev->flags))
+ tty_port_tty_wakeup(&dev->port);
+
tty_port_put(&dev->port);
}
@@ -373,7 +438,7 @@ static int rfcomm_create_dev(struct sock *sk, void __user *arg)
if (copy_from_user(&req, arg, sizeof(req)))
return -EFAULT;
- BT_DBG("sk %p dev_id %d flags 0x%x", sk, req.dev_id, req.flags);
+ BT_DBG("create sk %p dev_id %d flags 0x%x", sk, req.dev_id, req.flags);
if (req.flags != NOCAP_FLAGS && !capable(CAP_NET_ADMIN))
return -EPERM;
@@ -410,11 +475,12 @@ static int rfcomm_release_dev(void __user *arg)
{
struct rfcomm_dev_req req;
struct rfcomm_dev *dev;
+ struct tty_struct *tty;
if (copy_from_user(&req, arg, sizeof(req)))
return -EFAULT;
- BT_DBG("dev_id %d flags 0x%x", req.dev_id, req.flags);
+ BT_DBG("release dev_id %d flags 0x%x", req.dev_id, req.flags);
dev = rfcomm_dev_get(req.dev_id);
if (!dev)
@@ -429,11 +495,16 @@ static int rfcomm_release_dev(void __user *arg)
rfcomm_dlc_close(dev->dlc, 0);
/* Shut down TTY synchronously before freeing rfcomm_dev */
- if (dev->port.tty)
- tty_vhangup(dev->port.tty);
+ tty = tty_port_tty_get(&dev->port);
+ if (tty) {
+ tty_vhangup(tty);
+ tty_kref_put(tty);
+ }
+
+ /* release the TTY */
+ if (!test_and_set_bit(RFCOMM_TTY_RELEASED, &dev->flags))
+ tty_port_put(&dev->port);
- if (!test_bit(RFCOMM_RELEASE_ONHUP, &dev->flags))
- rfcomm_dev_del(dev);
tty_port_put(&dev->port);
return 0;
}
@@ -446,7 +517,7 @@ static int rfcomm_get_dev_list(void __user *arg)
int n = 0, size, err;
u16 dev_num;
- BT_DBG("");
+ BT_DBG("get_dev_list");
if (get_user(dev_num, (u16 __user *) arg))
return -EFAULT;
@@ -494,7 +565,7 @@ static int rfcomm_get_dev_info(void __user *arg)
struct rfcomm_dev_info di;
int err = 0;
- BT_DBG("");
+ BT_DBG("get_dev_info");
if (copy_from_user(&di, arg, sizeof(di)))
return -EFAULT;
@@ -518,7 +589,7 @@ static int rfcomm_get_dev_info(void __user *arg)
int rfcomm_dev_ioctl(struct sock *sk, unsigned int cmd, void __user *arg)
{
- BT_DBG("cmd %d arg %p", cmd, arg);
+ BT_DBG("dev_ioctl cmd %d arg %p", cmd, arg);
switch (cmd) {
case RFCOMMCREATEDEV:
@@ -552,7 +623,7 @@ static void rfcomm_dev_data_ready(struct rfcomm_dlc *dlc, struct sk_buff *skb)
return;
}
- BT_DBG("dlc %p len %d", dlc, skb->len);
+ BT_DBG("dev_data_ready dlc %p len %d", dlc, skb->len);
tty_insert_flip_string(&dev->port, skb->data, skb->len);
tty_flip_buffer_push(&dev->port);
@@ -563,37 +634,17 @@ static void rfcomm_dev_data_ready(struct rfcomm_dlc *dlc, struct sk_buff *skb)
static void rfcomm_dev_state_change(struct rfcomm_dlc *dlc, int err)
{
struct rfcomm_dev *dev = dlc->owner;
+
if (!dev)
return;
- BT_DBG("dlc %p dev %p err %d", dlc, dev, err);
+ BT_DBG("dev_state_change dlc %p dev %p err %d", dlc, dev, err);
dev->err = err;
wake_up_interruptible(&dev->wait);
- if (dlc->state == BT_CLOSED) {
- if (!dev->port.tty) {
- if (test_bit(RFCOMM_RELEASE_ONHUP, &dev->flags)) {
- /* Drop DLC lock here to avoid deadlock
- * 1. rfcomm_dev_get will take rfcomm_dev_lock
- * but in rfcomm_dev_add there's lock order:
- * rfcomm_dev_lock -> dlc lock
- * 2. tty_port_put will deadlock if it's
- * the last reference
- */
- rfcomm_dlc_unlock(dlc);
- if (rfcomm_dev_get(dev->id) == NULL) {
- rfcomm_dlc_lock(dlc);
- return;
- }
-
- rfcomm_dev_del(dev);
- tty_port_put(&dev->port);
- rfcomm_dlc_lock(dlc);
- }
- } else
- tty_hangup(dev->port.tty);
- }
+ if (dlc->state == BT_CLOSED)
+ tty_port_tty_hangup(&dev->port, false);
}
static void rfcomm_dev_modem_status(struct rfcomm_dlc *dlc, u8 v24_sig)
@@ -602,12 +653,11 @@ static void rfcomm_dev_modem_status(struct rfcomm_dlc *dlc, u8 v24_sig)
if (!dev)
return;
- BT_DBG("dlc %p dev %p v24_sig 0x%02x", dlc, dev, v24_sig);
+ BT_DBG("dev_modem_status dlc %p dev %p v24_sig 0x%02x",
+ dlc, dev, v24_sig);
- if ((dev->modem_status & TIOCM_CD) && !(v24_sig & RFCOMM_V24_DV)) {
- if (dev->port.tty && !C_CLOCAL(dev->port.tty))
- tty_hangup(dev->port.tty);
- }
+ if ((dev->modem_status & TIOCM_CD) && !(v24_sig & RFCOMM_V24_DV))
+ tty_port_tty_hangup(&dev->port, true);
dev->modem_status =
((v24_sig & RFCOMM_V24_RTC) ? (TIOCM_DSR | TIOCM_DTR) : 0) |
@@ -617,145 +667,86 @@ static void rfcomm_dev_modem_status(struct rfcomm_dlc *dlc, u8 v24_sig)
}
/* ---- TTY functions ---- */
-static void rfcomm_tty_copy_pending(struct rfcomm_dev *dev)
-{
- struct sk_buff *skb;
- int inserted = 0;
-
- BT_DBG("dev %p", dev);
-
- rfcomm_dlc_lock(dev->dlc);
-
- while ((skb = skb_dequeue(&dev->pending))) {
- inserted += tty_insert_flip_string(&dev->port, skb->data,
- skb->len);
- kfree_skb(skb);
- }
-
- rfcomm_dlc_unlock(dev->dlc);
-
- if (inserted > 0)
- tty_flip_buffer_push(&dev->port);
-}
-
-static int rfcomm_tty_open(struct tty_struct *tty, struct file *filp)
+static int rfcomm_tty_install(struct tty_driver *driver, struct tty_struct *tty)
{
- DECLARE_WAITQUEUE(wait, current);
struct rfcomm_dev *dev;
- struct rfcomm_dlc *dlc;
- unsigned long flags;
- int err, id;
-
- id = tty->index;
+ int err;
- BT_DBG("tty %p id %d", tty, id);
+ BT_DBG("install tty %p id %d", tty, tty->index);
- /* We don't leak this refcount. For reasons which are not entirely
- clear, the TTY layer will call our ->close() method even if the
- open fails. We decrease the refcount there, and decreasing it
- here too would cause breakage. */
- dev = rfcomm_dev_get(id);
+ dev = rfcomm_dev_get(tty->index);
if (!dev)
return -ENODEV;
- BT_DBG("dev %p dst %pMR channel %d opened %d", dev, &dev->dst,
- dev->channel, dev->port.count);
-
- spin_lock_irqsave(&dev->port.lock, flags);
- if (++dev->port.count > 1) {
- spin_unlock_irqrestore(&dev->port.lock, flags);
- return 0;
- }
- spin_unlock_irqrestore(&dev->port.lock, flags);
-
- dlc = dev->dlc;
-
- /* Attach TTY and open DLC */
-
- rfcomm_dlc_lock(dlc);
+ /* Attach TTY */
+ rfcomm_dlc_lock(dev->dlc);
tty->driver_data = dev;
- dev->port.tty = tty;
- rfcomm_dlc_unlock(dlc);
+ rfcomm_dlc_unlock(dev->dlc);
set_bit(RFCOMM_TTY_ATTACHED, &dev->flags);
- err = rfcomm_dlc_open(dlc, &dev->src, &dev->dst, dev->channel);
- if (err < 0)
- return err;
+ err = tty_port_install(&dev->port, driver, tty);
+ if (err < 0) {
+ clear_bit(RFCOMM_TTY_ATTACHED, &dev->flags);
+ tty_port_put(&dev->port);
+ }
- /* Wait for DLC to connect */
- add_wait_queue(&dev->wait, &wait);
- while (1) {
- set_current_state(TASK_INTERRUPTIBLE);
+ return err;
+}
- if (dlc->state == BT_CLOSED) {
- err = -dev->err;
- break;
- }
+static void rfcomm_tty_cleanup(struct tty_struct *tty)
+{
+ struct rfcomm_dev *dev = tty->driver_data;
- if (dlc->state == BT_CONNECTED)
- break;
+ BT_DBG("cleanup tty %p id %d", tty, tty->index);
- if (signal_pending(current)) {
- err = -EINTR;
- break;
- }
+ /* Remove driver data */
+ clear_bit(RFCOMM_TTY_ATTACHED, &dev->flags);
+ rfcomm_dlc_lock(dev->dlc);
+ tty->driver_data = NULL;
+ rfcomm_dlc_unlock(dev->dlc);
- tty_unlock(tty);
- schedule();
- tty_lock(tty);
- }
- set_current_state(TASK_RUNNING);
- remove_wait_queue(&dev->wait, &wait);
+ /*
+ * there is a circular dependency between dev and dlc
+ * dev holds a reference to a dlc
+ * dlc->tx_queue hold skbufs with references to dev
+ * so purge the tx_queue
+ */
+ skb_queue_purge(&dev->dlc->tx_queue);
- if (err == 0)
- device_move(dev->tty_dev, rfcomm_get_device(dev),
- DPM_ORDER_DEV_AFTER_PARENT);
+ tty_port_put(&dev->port);
+}
- rfcomm_tty_copy_pending(dev);
+static int rfcomm_tty_open(struct tty_struct *tty, struct file *filp)
+{
+ struct rfcomm_dev *dev = tty->driver_data;
- rfcomm_dlc_unthrottle(dev->dlc);
+ BT_DBG("open tty %p id %d", tty, tty->index);
- return err;
+ return tty_port_open(&dev->port, tty, filp);
}
static void rfcomm_tty_close(struct tty_struct *tty, struct file *filp)
{
- struct rfcomm_dev *dev = (struct rfcomm_dev *) tty->driver_data;
- unsigned long flags;
+ struct rfcomm_dev *dev = tty->driver_data;
- if (!dev)
- return;
-
- BT_DBG("tty %p dev %p dlc %p opened %d", tty, dev, dev->dlc,
+ BT_DBG("close tty %p dev %p dlc %p opened %d", tty, dev, dev->dlc,
dev->port.count);
- spin_lock_irqsave(&dev->port.lock, flags);
- if (!--dev->port.count) {
- spin_unlock_irqrestore(&dev->port.lock, flags);
- if (dev->tty_dev->parent)
- device_move(dev->tty_dev, NULL, DPM_ORDER_DEV_LAST);
-
- /* Close DLC and dettach TTY */
- rfcomm_dlc_close(dev->dlc, 0);
-
- clear_bit(RFCOMM_TTY_ATTACHED, &dev->flags);
+ tty_port_close(&dev->port, tty, filp);
+}
- rfcomm_dlc_lock(dev->dlc);
- tty->driver_data = NULL;
- dev->port.tty = NULL;
- rfcomm_dlc_unlock(dev->dlc);
+static void rfcomm_tty_hangup(struct tty_struct *tty)
+{
+ struct rfcomm_dev *dev = tty->driver_data;
- if (test_bit(RFCOMM_TTY_RELEASED, &dev->flags)) {
- spin_lock(&rfcomm_dev_lock);
- list_del_init(&dev->list);
- spin_unlock(&rfcomm_dev_lock);
+ BT_DBG("hangup tty %p dev %p", tty, dev);
- tty_port_put(&dev->port);
- }
- } else
- spin_unlock_irqrestore(&dev->port.lock, flags);
+ tty_port_hangup(&dev->port);
- tty_port_put(&dev->port);
+ if (test_bit(RFCOMM_RELEASE_ONHUP, &dev->flags)) {
+ set_bit(RFCOMM_TTY_RELEASED, &dev->flags);
+ tty_port_put(&dev->port);
+ }
}
static int rfcomm_tty_write(struct tty_struct *tty, const unsigned char *buf, int count)
@@ -765,7 +756,7 @@ static int rfcomm_tty_write(struct tty_struct *tty, const unsigned char *buf, in
struct sk_buff *skb;
int err = 0, sent = 0, size;
- BT_DBG("tty %p count %d", tty, count);
+ BT_DBG("write tty %p count %d", tty, count);
while (count) {
size = min_t(uint, count, dlc->mtu);
@@ -797,7 +788,7 @@ static int rfcomm_tty_write_room(struct tty_struct *tty)
struct rfcomm_dev *dev = (struct rfcomm_dev *) tty->driver_data;
int room;
- BT_DBG("tty %p", tty);
+ BT_DBG("tty_write_room %p", tty);
if (!dev || !dev->dlc)
return 0;
@@ -1017,7 +1008,7 @@ static int rfcomm_tty_chars_in_buffer(struct tty_struct *tty)
BT_DBG("tty %p dev %p", tty, dev);
- if (!dev || !dev->dlc)
+ if (!dev)
return 0;
if (!skb_queue_empty(&dev->dlc->tx_queue))
@@ -1030,7 +1021,7 @@ static void rfcomm_tty_flush_buffer(struct tty_struct *tty)
{
struct rfcomm_dev *dev = (struct rfcomm_dev *) tty->driver_data;
- BT_DBG("tty %p dev %p", tty, dev);
+ BT_DBG("flush_buffer tty %p dev %p", tty, dev);
if (!dev || !dev->dlc)
return;
@@ -1049,25 +1040,6 @@ static void rfcomm_tty_wait_until_sent(struct tty_struct *tty, int timeout)
BT_DBG("tty %p timeout %d", tty, timeout);
}
-static void rfcomm_tty_hangup(struct tty_struct *tty)
-{
- struct rfcomm_dev *dev = (struct rfcomm_dev *) tty->driver_data;
-
- BT_DBG("tty %p dev %p", tty, dev);
-
- if (!dev)
- return;
-
- rfcomm_tty_flush_buffer(tty);
-
- if (test_bit(RFCOMM_RELEASE_ONHUP, &dev->flags)) {
- if (rfcomm_dev_get(dev->id) == NULL)
- return;
- rfcomm_dev_del(dev);
- tty_port_put(&dev->port);
- }
-}
-
static int rfcomm_tty_tiocmget(struct tty_struct *tty)
{
struct rfcomm_dev *dev = (struct rfcomm_dev *) tty->driver_data;
@@ -1128,6 +1100,8 @@ static const struct tty_operations rfcomm_ops = {
.wait_until_sent = rfcomm_tty_wait_until_sent,
.tiocmget = rfcomm_tty_tiocmget,
.tiocmset = rfcomm_tty_tiocmset,
+ .install = rfcomm_tty_install,
+ .cleanup = rfcomm_tty_cleanup,
};
int __init rfcomm_init_ttys(void)
