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From: Dean Jenkins <Dean_Jenkins@mentor.com>
To: Marcel Holtmann <marcel@holtmann.org>
Cc: Dean Jenkins <Dean_Jenkins@mentor.com>,
	"Gustavo F . Padovan" <gustavo@padovan.org>,
	Johan Hedberg <johan.hedberg@gmail.com>,
	<linux-bluetooth@vger.kernel.org>
Subject: [RFC V1 14/16] Bluetooth: hci_ldisc: Simplify flushing
Date: Tue, 28 Mar 2017 18:50:27 +0100	[thread overview]
Message-ID: <1490723429-28870-15-git-send-email-Dean_Jenkins@mentor.com> (raw)
In-Reply-To: <1490723429-28870-1-git-send-email-Dean_Jenkins@mentor.com>

The flushing due to the hci_uart_close() call probably corrupts the
data flow between the Data Link protocol layer and the UART port
(transmission direction). In any case, the flushing activity is
asynchronous to the state of the Data Link protocol layer so is
undesirable.

Modify hci_uart_close() to not perform any flushing because
hci_uart_flush() is explicitly called in hci_dev_do_close() which
is synchronous to the closure of the Data Link protocol layer so
it is OK. In other words, there is no point in flushing multiple
times with the Data Link protocol layer being in the bound state.

In hci_uart_tty_close() call hci_uart_flush() instead of
hci_uart_close() before freeing hdev. This final flush is after the
Data Link protocol layer has been unbound so ensures that the
transmission path is empty.

Signed-off-by: Dean Jenkins <Dean_Jenkins@mentor.com>
---
 drivers/bluetooth/hci_ldisc.c | 5 ++---
 1 file changed, 2 insertions(+), 3 deletions(-)

diff --git a/drivers/bluetooth/hci_ldisc.c b/drivers/bluetooth/hci_ldisc.c
index ad2dec5..0a10ee1 100644
--- a/drivers/bluetooth/hci_ldisc.c
+++ b/drivers/bluetooth/hci_ldisc.c
@@ -244,8 +244,7 @@ static int hci_uart_close(struct hci_dev *hdev)
 {
 	BT_DBG("hdev %p", hdev);
 
-	hci_uart_flush(hdev);
-	hdev->flush = NULL;
+	/* Nothing to do for UART driver */
 	return 0;
 }
 
@@ -514,7 +513,7 @@ static void hci_uart_tty_close(struct tty_struct *tty)
 	clear_bit(HCI_UART_PROTO_SET, &hu->flags);
 
 	if (test_and_clear_bit(HCI_UART_REGISTERED, &hu->flags)) {
-		hci_uart_close(hdev);
+		hci_uart_flush(hdev);
 		hu->hdev = NULL;
 		hci_free_dev(hdev);
 	}
-- 
2.7.4

  parent reply	other threads:[~2017-03-28 17:50 UTC|newest]

Thread overview: 25+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2017-03-28 17:50 [RFC V1 00/16] hci_ldisc hci_uart_tty_close() fixes Dean Jenkins
2017-03-28 17:50 ` [RFC V1 01/16] Bluetooth: hci_ldisc: Add missing return in hci_uart_init_work() Dean Jenkins
2017-03-28 17:50 ` [RFC V1 02/16] Bluetooth: hci_ldisc: Ensure hu->hdev set to NULL before freeing hdev Dean Jenkins
2017-03-28 17:50 ` [RFC V1 03/16] Bluetooth: hci_ldisc: Add missing clear HCI_UART_PROTO_READY Dean Jenkins
2017-03-28 17:50 ` [RFC V1 04/16] Bluetooth: hci_ldisc: Add HCI RESET comment to hci_unregister_dev() call Dean Jenkins
2017-03-30 10:11   ` Marcel Holtmann
2017-03-28 17:50 ` [RFC V1 05/16] Bluetooth: hci_ldisc: Add protocol check to hci_uart_send_frame() Dean Jenkins
2017-03-28 17:50 ` [RFC V1 06/16] Bluetooth: hci_ldisc: Add protocol check to hci_uart_dequeue() Dean Jenkins
2017-03-28 17:50 ` [RFC V1 07/16] Bluetooth: hci_ldisc: Add protocol check to hci_uart_tx_wakeup() Dean Jenkins
2017-03-30 10:11   ` Marcel Holtmann
2017-03-28 17:50 ` [RFC V1 08/16] Bluetooth: hci_ldisc: Separate flag handling in hci_uart_tty_close() Dean Jenkins
2017-03-28 17:50 ` [RFC V1 09/16] Bluetooth: hci_ldisc: Tidy-up HCI_UART_REGISTERED " Dean Jenkins
2017-03-28 17:50 ` [RFC V1 10/16] Bluetooth: hci_ldisc: hci_uart_tty_close() detach tty after last msg Dean Jenkins
2017-03-28 17:50 ` [RFC V1 11/16] Bluetooth: hci_ldisc: hci_uart_tty_close() move hci_uart_close() Dean Jenkins
2017-03-28 17:50 ` [RFC V1 12/16] Bluetooth: hci_ldisc: hci_uart_tty_close() move cancel_work_sync() Dean Jenkins
2017-03-28 17:50 ` [RFC V1 13/16] Bluetooth: hci_ldisc: hci_uart_tty_close() free hu->tx_skb Dean Jenkins
2017-03-28 17:50 ` Dean Jenkins [this message]
2017-03-28 17:50 ` [RFC V1 15/16] Bluetooth: hci_ldisc: Use rwlocking to avoid closing proto races Dean Jenkins
2017-03-28 17:50 ` [RFC V1 16/16] Bluetooth: hci_ldisc: Add ioctl_mutex avoiding concurrency Dean Jenkins
2017-03-30 10:11 ` [RFC V1 00/16] hci_ldisc hci_uart_tty_close() fixes Marcel Holtmann
2017-04-03 15:09   ` Dean Jenkins
2017-04-03 15:51     ` Marcel Holtmann
2017-04-04 20:36       ` Dean Jenkins
2017-04-05 15:28         ` Dean Jenkins
2017-04-06  7:23           ` Marcel Holtmann

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