[PATCH] spi: Fix race condition in stop_queue()

[Vasily Khoruzhick]

There's a race condition in stop_queue() in some drivers -
if drv_data->queue is empty, but drv_data->busy is still set
(or opposite situation) stop_queue will return -EBUSY.
So fix loop condition to check that both drv_data->queue is empty
and drv_data->busy is not set.

This patch affects following drivers:
pxa2xx_spi
spi_bfin5xx
amba-pl022
dw_spi

Signed-off-by: Vasily Khoruzhick <anarsoul at gmail.com>
---
 drivers/spi/amba-pl022.c  |    2 +-
 drivers/spi/dw_spi.c      |    2 +-
 drivers/spi/pxa2xx_spi.c  |    2 +-
 drivers/spi/spi_bfin5xx.c |    2 +-
 4 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/spi/amba-pl022.c b/drivers/spi/amba-pl022.c
index 71a1219..23aaaa9 100644
--- a/drivers/spi/amba-pl022.c
+++ b/drivers/spi/amba-pl022.c
@@ -1553,7 +1553,7 @@ static int stop_queue(struct pl022 *pl022)
 	 * A wait_queue on the pl022->busy could be used, but then the common
 	 * execution path (pump_messages) would be required to call wake_up or
 	 * friends on every SPI message. Do this instead */
-	while (!list_empty(&pl022->queue) && pl022->busy && limit--) {
+	while ((!list_empty(&pl022->queue) || pl022->busy) && limit--) {
 		spin_unlock_irqrestore(&pl022->queue_lock, flags);
 		msleep(10);
 		spin_lock_irqsave(&pl022->queue_lock, flags);
diff --git a/drivers/spi/dw_spi.c b/drivers/spi/dw_spi.c
index 22af77f..b53be4d 100644
--- a/drivers/spi/dw_spi.c
+++ b/drivers/spi/dw_spi.c
@@ -821,7 +821,7 @@ static int stop_queue(struct dw_spi *dws)
 
 	spin_lock_irqsave(&dws->lock, flags);
 	dws->run = QUEUE_STOPPED;
-	while (!list_empty(&dws->queue) && dws->busy && limit--) {
+	while ((!list_empty(&dws->queue) || dws->busy) && limit--) {
 		spin_unlock_irqrestore(&dws->lock, flags);
 		msleep(10);
 		spin_lock_irqsave(&dws->lock, flags);
diff --git a/drivers/spi/pxa2xx_spi.c b/drivers/spi/pxa2xx_spi.c
index 9592883..39cc10f 100644
--- a/drivers/spi/pxa2xx_spi.c
+++ b/drivers/spi/pxa2xx_spi.c
@@ -1493,7 +1493,7 @@ static int stop_queue(struct driver_data *drv_data)
 	 * execution path (pump_messages) would be required to call wake_up or
 	 * friends on every SPI message. Do this instead */
 	drv_data->run = QUEUE_STOPPED;
-	while (!list_empty(&drv_data->queue) && drv_data->busy && limit--) {
+	while ((!list_empty(&drv_data->queue) || drv_data->busy) && limit--) {
 		spin_unlock_irqrestore(&drv_data->lock, flags);
 		msleep(10);
 		spin_lock_irqsave(&drv_data->lock, flags);
diff --git a/drivers/spi/spi_bfin5xx.c b/drivers/spi/spi_bfin5xx.c
index 3f22351..0e14f40 100644
--- a/drivers/spi/spi_bfin5xx.c
+++ b/drivers/spi/spi_bfin5xx.c
@@ -1244,7 +1244,7 @@ static inline int bfin_spi_stop_queue(struct bfin_spi_master_data *drv_data)
 	 * friends on every SPI message. Do this instead
 	 */
 	drv_data->running = false;
-	while (!list_empty(&drv_data->queue) && drv_data->busy && limit--) {
+	while ((!list_empty(&drv_data->queue) || drv_data->busy) && limit--) {
 		spin_unlock_irqrestore(&drv_data->lock, flags);
 		msleep(10);
 		spin_lock_irqsave(&drv_data->lock, flags);
-- 
1.7.4.1