commit 850a28ecd8044ef36b2c7699d2e3736a410b4d0a
author Vasily Khoruzhick <anarsoul@gmail.com> Wed Apr 06 17:49:15 2011 +0300
committer Grant Likely <grant.likely@secretlab.ca> Thu Apr 07 11:17:45 2011 -0700
tree 42a67f4ca8a624df752ad790fe0614fa584817d6
parent 454abcc57f1d48a976291bc4af73b5f087e21d70

spi: Fix race condition in stop_queue()

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@gmail.com>
Acked-by: Eric Miao <eric.y.miao@gmail.com>
Acked-by: Mike Frysinger <vapier@gentoo.org>
Signed-off-by: Grant Likely <grant.likely@secretlab.ca>

drivers/spi/amba-pl022.c

diff --git a/drivers/spi/amba-pl022.c b/drivers/spi/amba-pl022.c
index 5a4e0af..4b8357b 100644
--- a/drivers/spi/amba-pl022.c
+++ b/drivers/spi/amba-pl022.c
@@ -1555,7 +1555,7 @@
 	 * 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);

drivers/spi/dw_spi.c

diff --git a/drivers/spi/dw_spi.c b/drivers/spi/dw_spi.c
index 9a61964..d040deb 100644
--- a/drivers/spi/dw_spi.c
+++ b/drivers/spi/dw_spi.c
@@ -821,7 +821,7 @@
 
 	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);

drivers/spi/pxa2xx_spi.c

diff --git a/drivers/spi/pxa2xx_spi.c b/drivers/spi/pxa2xx_spi.c
index a429b01..3aa7820 100644
--- a/drivers/spi/pxa2xx_spi.c
+++ b/drivers/spi/pxa2xx_spi.c
@@ -1493,7 +1493,7 @@
 	 * 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);

drivers/spi/spi_bfin5xx.c

diff --git a/drivers/spi/spi_bfin5xx.c b/drivers/spi/spi_bfin5xx.c
index a284624..f3a1c52 100644
--- a/drivers/spi/spi_bfin5xx.c
+++ b/drivers/spi/spi_bfin5xx.c
@@ -1284,7 +1284,7 @@
 	 * 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);