linux-kernel - [PATCH v4 15/21] serial: omap: unlock the port lock

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Message-Id: <1346935540-1792-16-git-send-email-balbi@ti.com>
Date:	Thu,  6 Sep 2012 15:45:34 +0300
From:	Felipe Balbi <balbi@...com>
To:	Greg KH <gregkh@...uxfoundation.org>
Cc:	alan@...ux.intel.com, Tony Lindgren <tony@...mide.com>,
	Kevin Hilman <khilman@...com>,
	Linux OMAP Mailing List <linux-omap@...r.kernel.org>,
	Linux ARM Kernel Mailing List 
	<linux-arm-kernel@...ts.infradead.org>,
	linux-serial@...r.kernel.org,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Santosh Shilimkar <santosh.shilimkar@...com>,
	Shubhrajyoti Datta <shubhrajyoti@...com>,
	Sourav Poddar <sourav.poddar@...com>,
	Ruchika Kharwar <ruchika@...com>,
	Pavan Savoy <pavan_savoy@...com>,
	Vijay Badawadagi <bvijay@...com>, Felipe Balbi <balbi@...com>
Subject: [PATCH v4 15/21] serial: omap: unlock the port lock

From: Ruchika Kharwar <ruchika@...com>

This patch unlocks the port lock before calling a serial_core API
and re-acquires the port lock after calling it.
This patch fixes a system freeze issue seen when the serial_core
API uart_write_wakeup() eventually attempts to acquire the port lock
already acquired by omap serial interrupt handler.

Tested-by: Shubhrajyoti D <shubhrajyoti@...com>
Signed-off-by: Ruchika Kharwar <ruchika@...com>
Signed-off-by: Pavan Savoy <pavan_savoy@...com>
Signed-off-by: Vijay Badawadagi <bvijay@...com>
Signed-off-by: Felipe Balbi <balbi@...com>
---
 drivers/tty/serial/omap-serial.c | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/drivers/tty/serial/omap-serial.c b/drivers/tty/serial/omap-serial.c
index d244163..9e4419c 100644
--- a/drivers/tty/serial/omap-serial.c
+++ b/drivers/tty/serial/omap-serial.c
@@ -224,8 +224,11 @@ static void transmit_chars(struct uart_omap_port *up, unsigned int lsr)
 			break;
 	} while (--count > 0);
 
-	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS) {
+		spin_unlock(&up->port.lock);
 		uart_write_wakeup(&up->port);
+		spin_lock(&up->port.lock);
+	}
 
 	if (uart_circ_empty(xmit))
 		serial_omap_stop_tx(&up->port);
-- 
1.7.12.rc3

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