[PATCHv2 1/4] coresight: tmc-etr: Use handle->head from perf_output_handle directly.

Daniel Kiss
2021-07-13T12:17:50Z

Polling might call update multiple times and the cached buffer head will
be out of sync without advancing it. Using the head directly from the
perf_output_handle solves this problem.

Signed-off-by: Daniel Kiss <daniel.kiss@arm.com>
---
drivers/hwtracing/coresight/coresight-tmc-etr.c | 13 +++++--------
1 file changed, 5 insertions(+), 8 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c
index acdb59e0e6614..589bb2d56e802 100644
--- a/drivers/hwtracing/coresight/coresight-tmc-etr.c
+++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c
@@ -32,7 +32,6 @@ struct etr_flat_buf {
* @etr_buf - Actual buffer used by the ETR
* @pid - The PID this etr_perf_buffer belongs to.
* @snaphost - Perf session mode
- * @head - handle->head at the beginning of the session.
* @nr_pages - Number of pages in the ring buffer.
* @pages - Array of Pages in the ring buffer.
*/
@@ -41,7 +40,6 @@ struct etr_perf_buffer {
struct etr_buf *etr_buf;
pid_t pid;
bool snapshot;
- unsigned long head;
int nr_pages;
void **pages;
};
@@ -1436,17 +1434,18 @@ static void tmc_free_etr_buffer(void *config)
* tmc_etr_sync_perf_buffer: Copy the actual trace data from the hardware
* buffer to the perf ring buffer.
*/
-static void tmc_etr_sync_perf_buffer(struct etr_perf_buffer *etr_perf,
+static void tmc_etr_sync_perf_buffer(struct perf_output_handle *handle,
+ struct etr_perf_buffer *etr_perf,
unsigned long src_offset,
unsigned long to_copy)
{
long bytes;
long pg_idx, pg_offset;
- unsigned long head = etr_perf->head;
+ unsigned long head;
char **dst_pages, *src_buf;
struct etr_buf *etr_buf = etr_perf->etr_buf;

- head = etr_perf->head;
+ head = PERF_IDX2OFF(handle->head, etr_perf);
pg_idx = head >> PAGE_SHIFT;
pg_offset = head & (PAGE_SIZE - 1);
dst_pages = (char **)etr_perf->pages;
@@ -1553,7 +1552,7 @@ tmc_update_etr_buffer(struct coresight_device *csdev,
/* Insert barrier packets at the beginning, if there was an overflow */
if (lost)
tmc_etr_buf_insert_barrier_packet(etr_buf, offset);
- tmc_etr_sync_perf_buffer(etr_perf, offset, size);
+ tmc_etr_sync_perf_buffer(handle, etr_perf, offset, size);

/*
* In snapshot mode we simply increment the head by the number of byte
@@ -1605,8 +1604,6 @@ static int tmc_enable_etr_sink_perf(struct coresight_device *csdev, void *data)
goto unlock_out;
}

- etr_perf->head = PERF_IDX2OFF(handle->head, etr_perf);
-
/*
* No HW configuration is needed if the sink is already in
* use for this session.
--
2.25.1