UPSTREAM: coresight: tmc-etr: Decouple buffer sync and barrier packet insertion

(Upstream commit 3507d231a499e27c4bac8a47169b74ec7ef87292).

If less space is available in the perf ring buffer than the ETR buffer,
barrier packets inserted in the trace stream by tmc_sync_etr_buf() are
skipped over when the head of the buffer is moved forward, resulting in
traces that can't be decoded.

This patch decouples the process of syncing ETR buffers and the addition
of barrier packets in order to perform the latter once the offset in the
trace buffer has been properly computed.

Signed-off-by: Mathieu Poirier <mathieu.poirier@linaro.org>
Reviewed-by: Leo Yan <leo.yan@linaro.org>
Link: https://lore.kernel.org/r/20190829202842.580-17-mathieu.poirier@linaro.org


Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Bug: 140266694
Change-Id: I2ecf6cdb2cde8180adc4ccd06e7916c89416c629
Signed-off-by: Yabin Cui <yabinc@google.com>