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

[Eric Miao]

On Wed, Apr 6, 2011 at 10:49 PM, Vasily Khoruzhick <anarsoul at gmail.com> wrote:
> 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>

Acked-by: Eric Miao <eric.y.miao 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
>
>