linux-kernel - [ 005/167] [PATCH] ARM: clps711x: serial driver hungs are a result of call disable

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Message-Id: <20120509055030.317834781@decadent.org.uk>
Date:	Wed, 09 May 2012 06:50:34 +0100
From:	Ben Hutchings <ben@...adent.org.uk>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	torvalds@...ux-foundation.org, akpm@...ux-foundation.org,
	alan@...rguk.ukuu.org.uk, Alexander Shiyan <shc_work@...l.ru>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Subject: [ 005/167] [PATCH] ARM: clps711x: serial driver hungs are a result of call
 disable_irq within ISR

3.2-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Alexander Shiyan <shc_work@...l.ru>

commit 7a6fbc9a887193a1e9f8658703881c528040afbc upstream.

Since 2.6.30-rc1 clps711x serial driver hungs system. This is a result
of call disable_irq from ISR. synchronize_irq waits for end of interrupt
and goes to infinite loop. This patch fix this problem.

Signed-off-by: Alexander Shiyan <shc_work@...l.ru>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 drivers/tty/serial/clps711x.c |   14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/drivers/tty/serial/clps711x.c b/drivers/tty/serial/clps711x.c
index e6c3dbd..836fe273 100644
--- a/drivers/tty/serial/clps711x.c
+++ b/drivers/tty/serial/clps711x.c
@@ -154,10 +154,9 @@ static irqreturn_t clps711xuart_int_tx(int irq, void *dev_id)
 		port->x_char = 0;
 		return IRQ_HANDLED;
 	}
-	if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
-		clps711xuart_stop_tx(port);
-		return IRQ_HANDLED;
-	}
+
+	if (uart_circ_empty(xmit) || uart_tx_stopped(port))
+		goto disable_tx_irq;
 
 	count = port->fifosize >> 1;
 	do {
@@ -171,8 +170,11 @@ static irqreturn_t clps711xuart_int_tx(int irq, void *dev_id)
 	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
 		uart_write_wakeup(port);
 
-	if (uart_circ_empty(xmit))
-		clps711xuart_stop_tx(port);
+	if (uart_circ_empty(xmit)) {
+	disable_tx_irq:
+		disable_irq_nosync(TX_IRQ(port));
+		tx_enabled(port) = 0;
+	}
 
 	return IRQ_HANDLED;
 }
-- 
1.7.10



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