The read pointer (read_ptr) needs to be adjusted only if its value
has gone beyond the length of the memory buffer.

Reported-by: Suzuki K Poulose <suzuki.poul...@arm.com>
Signed-off-by: Mathieu Poirier <mathieu.poir...@linaro.org>
---
 drivers/hwtracing/coresight/coresight-etb10.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/hwtracing/coresight/coresight-etb10.c 
b/drivers/hwtracing/coresight/coresight-etb10.c
index 586c98fbdb03..1e4031ee8969 100644
--- a/drivers/hwtracing/coresight/coresight-etb10.c
+++ b/drivers/hwtracing/coresight/coresight-etb10.c
@@ -428,7 +428,8 @@ static void etb_update_buffer(struct coresight_device 
*csdev,
                read_ptr = (write_ptr + drvdata->buffer_depth) -
                                        to_read / ETB_FRAME_SIZE_WORDS;
                /* Wrap around if need be*/
-               read_ptr &= ~(drvdata->buffer_depth - 1);
+               if (read_ptr > (drvdata->buffer_depth - 1))
+                       read_ptr -= drvdata->buffer_depth;
                /* let the decoder know we've skipped ahead */
                local_inc(&buf->lost);
        }
-- 
2.5.0

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