rx_lock spinlock is only used in hci_uart_tty_receive() which is the
receive_buf ldisc callback.
hci_uart_tty_receive() is protected from re-entrance by its only
caller (flush_to_ldisc() in drivers/tty/tty_buffer.c) which held a
mutex (buf->lock) for this section.
This lock allows "safe use of the line discipline's receive_buf()
method by excluding the buffer work and any pending flush from using
the flip buffer." (comments from tty_buffer_lock_exclusive() in
drivers/tty/tty_buffer.c)
So, no need to double protect this resource with rx_lock.
Signed-off-by: Frederic Danis <frederic.danis@xxxxxxxxxxxxxxx>
---
drivers/bluetooth/hci_ldisc.c | 8 +++-----
drivers/bluetooth/hci_uart.h | 1 -
2 files changed, 3 insertions(+), 6 deletions(-)
diff --git a/drivers/bluetooth/hci_ldisc.c b/drivers/bluetooth/hci_ldisc.c
index 0d5a05a..ad66c69 100644
--- a/drivers/bluetooth/hci_ldisc.c
+++ b/drivers/bluetooth/hci_ldisc.c
@@ -470,8 +470,6 @@ 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);
- spin_lock_init(&hu->rx_lock);
-
/* Flush any pending characters in the driver and line discipline. */
/* FIXME: why is this needed. Note don't use ldisc_ref here as the
@@ -569,14 +567,14 @@ static void hci_uart_tty_receive(struct tty_struct *tty, const u8 *data,
if (!test_bit(HCI_UART_PROTO_SET, &hu->flags))
return;
- spin_lock(&hu->rx_lock);
+ /* It does not need a lock here as it is already protected by a mutex in
+ * tty caller
+ */
hu->proto->recv(hu, data, count);
if (hu->hdev)
hu->hdev->stat.byte_rx += count;
- spin_unlock(&hu->rx_lock);
-
tty_unthrottle(tty);
}
diff --git a/drivers/bluetooth/hci_uart.h b/drivers/bluetooth/hci_uart.h
index 495b9ef..2f7bb35 100644
--- a/drivers/bluetooth/hci_uart.h
+++ b/drivers/bluetooth/hci_uart.h
@@ -85,7 +85,6 @@ struct hci_uart {
struct sk_buff *tx_skb;
unsigned long tx_state;
- spinlock_t rx_lock;
unsigned int init_speed;
unsigned int oper_speed;
--
1.9.1
--
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