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

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>

(Upstream commit 3507d231a499e27c4bac8a47169b74ec7ef87292).

Bug: 140266694
Change-Id: I2bc0429aacb32cc59cf2e002530a00c8c2909683
Signed-off-by: Yabin Cui <yabinc@google.com>