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Bluetooth: Remove useless rx_lock spinlock

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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@linux.intel.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
This commit is contained in:
Frederic Danis 2015-09-23 18:18:10 +02:00 committed by Marcel Holtmann
parent b7a622a249
commit 7649faff1c
2 changed files with 3 additions and 6 deletions
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8
drivers/bluetooth/hci_ldisc.c
View file

@ -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);
}

1
drivers/bluetooth/hci_uart.h
View file

@ -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;