From 7649faff1cfe4f76dabf78cd53d659d39f65b3c1 Mon Sep 17 00:00:00 2001 From: Frederic Danis Date: Wed, 23 Sep 2015 18:18:10 +0200 Subject: [PATCH] Bluetooth: Remove useless rx_lock spinlock 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 Signed-off-by: Marcel Holtmann --- 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 0d5a05a7c1fd..ad66c690d272 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 495b9ef52bb0..2f7bb35a890e 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; -- 2.30.2