Bluetooth: hci_ldisc: Allow sleeping while proto locks are held.

[mirror_ubuntu-bionic-kernel.git] / drivers / bluetooth / hci_ldisc.c

diff --git a/drivers/bluetooth/hci_ldisc.c b/drivers/bluetooth/hci_ldisc.c
index eec95019f15c819d3b6a5f46b107e160ccfd1216..31def781a562f4d6333a9a16c3cb1fc71d0269c4 100644 (file)
--- a/drivers/bluetooth/hci_ldisc.c
+++ b/drivers/bluetooth/hci_ldisc.c
@@ -115,12 +115,12 @@ static inline struct sk_buff *hci_uart_dequeue(struct hci_uart *hu)
        struct sk_buff *skb = hu->tx_skb;
 
        if (!skb) {
-               read_lock(&hu->proto_lock);
+               percpu_down_read(&hu->proto_lock);
 
                if (test_bit(HCI_UART_PROTO_READY, &hu->flags))
                        skb = hu->proto->dequeue(hu);
 
-               read_unlock(&hu->proto_lock);
+               percpu_up_read(&hu->proto_lock);
        } else {
                hu->tx_skb = NULL;
        }
@@ -130,7 +130,14 @@ static inline struct sk_buff *hci_uart_dequeue(struct hci_uart *hu)
 
 int hci_uart_tx_wakeup(struct hci_uart *hu)
 {
-       read_lock(&hu->proto_lock);
+       /* This may be called in an IRQ context, so we can't sleep. Therefore
+        * we try to acquire the lock only, and if that fails we assume the
+        * tty is being closed because that is the only time the write lock is
+        * acquired. If, however, at some point in the future the write lock
+        * is also acquired in other situations, then this must be revisited.
+        */
+       if (!percpu_down_read_trylock(&hu->proto_lock))
+               return 0;
 
        if (!test_bit(HCI_UART_PROTO_READY, &hu->flags))
                goto no_schedule;
@@ -145,7 +152,7 @@ int hci_uart_tx_wakeup(struct hci_uart *hu)
        schedule_work(&hu->write_work);
 
 no_schedule:
-       read_unlock(&hu->proto_lock);
+       percpu_up_read(&hu->proto_lock);
 
        return 0;
 }
@@ -247,12 +254,12 @@ static int hci_uart_flush(struct hci_dev *hdev)
        tty_ldisc_flush(tty);
        tty_driver_flush_buffer(tty);
 
-       read_lock(&hu->proto_lock);
+       percpu_down_read(&hu->proto_lock);
 
        if (test_bit(HCI_UART_PROTO_READY, &hu->flags))
                hu->proto->flush(hu);
 
-       read_unlock(&hu->proto_lock);
+       percpu_up_read(&hu->proto_lock);
 
        return 0;
 }
@@ -275,15 +282,15 @@ static int hci_uart_send_frame(struct hci_dev *hdev, struct sk_buff *skb)
        BT_DBG("%s: type %d len %d", hdev->name, hci_skb_pkt_type(skb),
               skb->len);
 
-       read_lock(&hu->proto_lock);
+       percpu_down_read(&hu->proto_lock);
 
        if (!test_bit(HCI_UART_PROTO_READY, &hu->flags)) {
-               read_unlock(&hu->proto_lock);
+               percpu_up_read(&hu->proto_lock);
                return -EUNATCH;
        }
 
        hu->proto->enqueue(hu, skb);
-       read_unlock(&hu->proto_lock);
+       percpu_up_read(&hu->proto_lock);
 
        hci_uart_tx_wakeup(hu);
 
@@ -486,7 +493,7 @@ static int hci_uart_tty_open(struct tty_struct *tty)
        INIT_WORK(&hu->init_ready, hci_uart_init_work);
        INIT_WORK(&hu->write_work, hci_uart_write_work);
 
-       rwlock_init(&hu->proto_lock);
+       percpu_init_rwsem(&hu->proto_lock);
 
        /* Flush any pending characters in the driver */
        tty_driver_flush_buffer(tty);
@@ -503,7 +510,6 @@ static void hci_uart_tty_close(struct tty_struct *tty)
 {
        struct hci_uart *hu = tty->disc_data;
        struct hci_dev *hdev;
-       unsigned long flags;
 
        BT_DBG("tty %p", tty);
 
@@ -520,9 +526,9 @@ static void hci_uart_tty_close(struct tty_struct *tty)
        cancel_work_sync(&hu->write_work);
 
        if (test_bit(HCI_UART_PROTO_READY, &hu->flags)) {
-               write_lock_irqsave(&hu->proto_lock, flags);
+               percpu_down_write(&hu->proto_lock);
                clear_bit(HCI_UART_PROTO_READY, &hu->flags);
-               write_unlock_irqrestore(&hu->proto_lock, flags);
+               percpu_up_write(&hu->proto_lock);
 
                if (hdev) {
                        if (test_bit(HCI_UART_REGISTERED, &hu->flags))
@@ -582,10 +588,10 @@ static void hci_uart_tty_receive(struct tty_struct *tty, const u8 *data,
        if (!hu || tty != hu->tty)
                return;
 
-       read_lock(&hu->proto_lock);
+       percpu_down_read(&hu->proto_lock);
 
        if (!test_bit(HCI_UART_PROTO_READY, &hu->flags)) {
-               read_unlock(&hu->proto_lock);
+               percpu_up_read(&hu->proto_lock);
                return;
        }
 
@@ -593,7 +599,7 @@ static void hci_uart_tty_receive(struct tty_struct *tty, const u8 *data,
         * tty caller
         */
        hu->proto->recv(hu, data, count);
-       read_unlock(&hu->proto_lock);
+       percpu_up_read(&hu->proto_lock);
 
        if (hu->hdev)
                hu->hdev->stat.byte_rx += count;