From: Dick Hollenbeck <dick@softplc.com>
Date: Wed, 2 Sep 2009 16:07:29 +0000 (+0100)
Subject: ARM: 5688/1: ks8695_serial: disable_irq() lockup
X-Git-Tag: firefly_0821_release~12971^2^2~4
X-Git-Url: http://demsky.eecs.uci.edu/git/?a=commitdiff_plain;h=c47a830c08a26a7c210ae16a0ffe3f56ba86ea69;p=firefly-linux-kernel-4.4.55.git

ARM: 5688/1: ks8695_serial: disable_irq() lockup

disable_irq() cannot be called from interrupt context without self imposed deadlock. This was happening in ks8695uart_stop_tx().

Signed-off-by: Dick Hollenbeck <dick@softplc.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
---

diff --git a/drivers/serial/serial_ks8695.c b/drivers/serial/serial_ks8695.c
index e0665630e4da..52db5cc3f900 100644
--- a/drivers/serial/serial_ks8695.c
+++ b/drivers/serial/serial_ks8695.c
@@ -110,7 +110,11 @@ static struct console ks8695_console;
 static void ks8695uart_stop_tx(struct uart_port *port)
 {
 	if (tx_enabled(port)) {
-		disable_irq(KS8695_IRQ_UART_TX);
+		/* use disable_irq_nosync() and not disable_irq() to avoid self
+		 * imposed deadlock by not waiting for irq handler to end,
+		 * since this ks8695uart_stop_tx() is called from interrupt context.
+		 */
+		disable_irq_nosync(KS8695_IRQ_UART_TX);
 		tx_enable(port, 0);
 	}
 }