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authorRob Clark <robdclark@gmail.com>2017-10-02 10:28:37 -0400
committerRob Clark <robdclark@gmail.com>2017-10-12 10:59:11 -0400
commitf44001e2637138d9d506efe8da67011f8170e860 (patch)
tree68139686d74b1472a379a16810726f3f6f728220 /drivers/gpu
parentaa3c2ba1c3a7c25d0440a8ac3ddd266c0f43b7b7 (diff)
drm/msm: use proper memory barriers for updating tail/head
Fixes intermittent corruption of cmdstream dump. Signed-off-by: Rob Clark <robdclark@gmail.com>
Diffstat (limited to 'drivers/gpu')
-rw-r--r--drivers/gpu/drm/msm/msm_rd.c12
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);