linux-kernel - [PATCH 10/11] Revert "serial: omap: unlock the port lock"

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Date:	Thu, 20 Mar 2014 14:30:06 -0500
From:	Felipe Balbi <balbi@...com>
To:	Greg KH <gregkh@...uxfoundation.org>
CC:	<linux-serial@...r.kernel.org>, <linux-bluetooth@...r.kernel.org>,
	<peter@...leysoftware.com>, <m-karicheri2@...com>,
	<b32955@...escale.com>,
	Linux OMAP Mailing List <linux-omap@...r.kernel.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Felipe Balbi <balbi@...com>
Subject: [PATCH 10/11] Revert "serial: omap: unlock the port lock"

This reverts commit 0324a821029e1f54e7a7f8fed48693cfce42dc0e.

That commit tried to fix a deadlock problem when using
hci_ldisc, but it turns out the bug was in hci_ldsic
all along where it was calling ->write() from within
->write_wakeup() callback.

The problem is that ->write_wakeup() was called with
port lock held and ->write() tried to grab the same
port lock.

Signed-off-by: Felipe Balbi <balbi@...com>
---
 drivers/tty/serial/omap-serial.c | 5 +----
 1 file changed, 1 insertion(+), 4 deletions(-)

diff --git a/drivers/tty/serial/omap-serial.c b/drivers/tty/serial/omap-serial.c
index b092d3d..be10e7e 100644
--- a/drivers/tty/serial/omap-serial.c
+++ b/drivers/tty/serial/omap-serial.c
@@ -380,11 +380,8 @@ static void transmit_chars(struct uart_omap_port *up, unsigned int lsr)
 			break;
 	} while (--count > 0);
 
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS) {
-		spin_unlock(&up->port.lock);
+	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
 		uart_write_wakeup(&up->port);
-		spin_lock(&up->port.lock);
-	}
 
 	if (uart_circ_empty(xmit))
 		serial_omap_stop_tx(&up->port);
-- 
1.9.1.286.g5172cb3

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