linux-kernel - [PATCH v2 14/17] coresight: trbe: Make sure we have enough space

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Message-Id: <20210921134121.2423546-15-suzuki.poulose@arm.com>
Date:   Tue, 21 Sep 2021 14:41:18 +0100
From:   Suzuki K Poulose <suzuki.poulose@....com>
To:     linux-arm-kernel@...ts.infradead.org
Cc:     linux-kernel@...r.kernel.org, maz@...nel.org,
        catalin.marinas@....com, mark.rutland@....com, james.morse@....com,
        anshuman.khandual@....com, leo.yan@...aro.org,
        mike.leach@...aro.org, mathieu.poirier@...aro.org, will@...nel.org,
        lcherian@...vell.com, coresight@...ts.linaro.org,
        Suzuki K Poulose <suzuki.poulose@....com>
Subject: [PATCH v2 14/17] 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>
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 3373f4e2183b..02f9e00e2091 100644
--- a/drivers/hwtracing/coresight/coresight-trbe.c
+++ b/drivers/hwtracing/coresight/coresight-trbe.c
@@ -451,10 +451,14 @@ 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;
 }
-- 
2.24.1