linux-kernel - [PATCH v6 12/15] coresight: trbe: Make sure we have enough space

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Message-Id: <20211019163153.3692640-13-suzuki.poulose@arm.com>
Date:   Tue, 19 Oct 2021 17:31:50 +0100
From:   Suzuki K Poulose <suzuki.poulose@....com>
To:     will@...nel.org, mathieu.poirier@...aro.org
Cc:     catalin.marinas@....com, anshuman.khandual@....com,
        mike.leach@...aro.org, leo.yan@...aro.org, maz@...nel.org,
        coresight@...ts.linaro.org, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org,
        Suzuki K Poulose <suzuki.poulose@....com>
Subject: [PATCH v6 12/15] coresight: trbe: Make sure we have enough space

The TRBE driver makes sure that there is enough space for a meaningful
run, otherwise pads the given space and restarts the offset calculation
once. But there is no guarantee that we may find space or hit "no space".
Make sure that we repeat the step until, either :
  - We have the minimum space
   OR
  - There is NO space at all.

Cc: Anshuman Khandual <anshuman.khandual@....com>
Cc: Mathieu Poirier <mathieu.poirier@...aro.org>
Cc: Mike Leach <mike.leach@...aro.org>
Cc: Leo Yan <leo.yan@...aro.org>
Reviewed-by: Mathieu Poirier <mathieu.poirier@...aro.org>
Reviewed-by: Anshuman Khandual <anshuman.khandual@....com>
Signed-off-by: Suzuki K Poulose <suzuki.poulose@....com>
---
 drivers/hwtracing/coresight/coresight-trbe.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/drivers/hwtracing/coresight/coresight-trbe.c b/drivers/hwtracing/coresight/coresight-trbe.c
index 02a639ece2af..11ff33ec83b9 100644
--- a/drivers/hwtracing/coresight/coresight-trbe.c
+++ b/drivers/hwtracing/coresight/coresight-trbe.c
@@ -477,10 +477,14 @@ static unsigned long trbe_normal_offset(struct perf_output_handle *handle)
 	 * If the head is too close to the limit and we don't
 	 * have space for a meaningful run, we rather pad it
 	 * and start fresh.
+	 *
+	 * We might have to do this more than once to make sure
+	 * we have enough required space.
 	 */
-	if (limit && ((limit - head) < trbe_min_trace_buf_size(handle))) {
+	while (limit && ((limit - head) < trbe_min_trace_buf_size(handle))) {
 		trbe_pad_buf(handle, limit - head);
 		limit = __trbe_normal_offset(handle);
+		head = PERF_IDX2OFF(handle->head, buf);
 	}
 	return limit;
 }
-- 
2.25.4