virtio/s390: fix race on airq_areas[]

[platform/kernel/linux-rpi.git] / drivers / s390 / virtio / virtio_ccw.c

diff --git a/drivers/s390/virtio/virtio_ccw.c b/drivers/s390/virtio/virtio_ccw.c
index ec54538..67efdf2 100644 (file)
--- a/drivers/s390/virtio/virtio_ccw.c
+++ b/drivers/s390/virtio/virtio_ccw.c
@@ -132,6 +132,7 @@ struct airq_info {
        struct airq_iv *aiv;
 };
 static struct airq_info *airq_areas[MAX_AIRQ_AREAS];
+static DEFINE_MUTEX(airq_areas_lock);
 
 #define CCW_CMD_SET_VQ 0x13
 #define CCW_CMD_VDEV_RESET 0x33
@@ -244,9 +245,11 @@ static unsigned long get_airq_indicator(struct virtqueue *vqs[], int nvqs,
        unsigned long bit, flags;
 
        for (i = 0; i < MAX_AIRQ_AREAS && !indicator_addr; i++) {
+               mutex_lock(&airq_areas_lock);
                if (!airq_areas[i])
                        airq_areas[i] = new_airq_info();
                info = airq_areas[i];
+               mutex_unlock(&airq_areas_lock);
                if (!info)
                        return 0;
                write_lock_irqsave(&info->lock, flags);