1 files changed, 10 insertions, 2 deletions

diff --git a/drivers/gpu/drm/msm/msm_rd.c b/drivers/gpu/drm/msm/msm_rd.c
index 0366b8092f97..ec56794ad039 100644
--- a/drivers/gpu/drm/msm/msm_rd.c
+++ b/drivers/gpu/drm/msm/msm_rd.c
@@ -111,10 +111,14 @@ static void rd_write(struct msm_rd_state *rd, const void *buf, int sz)
 
                 wait_event(rd->fifo_event, circ_space(&rd->fifo) > 0);
 
+                /* Note that smp_load_acquire() is not strictly required
+                 * as CIRC_SPACE_TO_END() does not access the tail more
+                 * than once.
+                 */
                 n = min(sz, circ_space_to_end(&rd->fifo));
                 memcpy(fptr, ptr, n);
 
-                fifo->head = (fifo->head + n) & (BUF_SZ - 1);
+                smp_store_release(&fifo->head, (fifo->head + n) & (BUF_SZ - 1));
                 sz  -= n;
                 ptr += n;
 
@@ -145,13 +149,17 @@ static ssize_t rd_read(struct file *file, char __user *buf,
         if (ret)
                 goto out;
 
+        /* Note that smp_load_acquire() is not strictly required
+         * as CIRC_CNT_TO_END() does not access the head more than
+         * once.
+         */
         n = min_t(int, sz, circ_count_to_end(&rd->fifo));
         if (copy_to_user(buf, fptr, n)) {
                 ret = -EFAULT;
                 goto out;
         }
 
-        fifo->tail = (fifo->tail + n) & (BUF_SZ - 1);
+        smp_store_release(&fifo->tail, (fifo->tail + n) & (BUF_SZ - 1));
         *ppos += n;
 
         wake_up_all(&rd->fifo_event);