[PATCH 1/4] coresight: tmc-etr: Advance buffer pointer in sync buffer.

[Leo Yan]

On Wed, Apr 21, 2021 at 02:04:10PM +0200, Daniel Kiss wrote:
> With polling the sync could called multiple times in a row. Without this
> change the data will be overwritten at the beginning of the buffer.
> 
> Signed-off-by: Daniel Kiss <daniel.kiss at arm.com>
> Signed-off-by: Branislav Rankov <Branislav.Rankov at arm.com>

>From the last week, I spent time to dig into AUX trace buffer, thus
this patch set gives me a good chance to apply my learning for perf
ring buffer.

For this patch:

Reviewed-by: Leo Yan <leo.yan at linaro.org>


> ---
>  drivers/hwtracing/coresight/coresight-tmc-etr.c | 5 +++--
>  1 file changed, 3 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c
> index ea5027e397d02..dd19d1d1c3b38 100644
> --- a/drivers/hwtracing/coresight/coresight-tmc-etr.c
> +++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c
> @@ -1442,7 +1442,7 @@ static void tmc_etr_sync_perf_buffer(struct etr_perf_buffer *etr_perf,
>  {
>  	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;
>  
> @@ -1465,7 +1465,7 @@ static void tmc_etr_sync_perf_buffer(struct etr_perf_buffer *etr_perf,
>  		bytes = tmc_etr_buf_get_data(etr_buf, src_offset, to_copy,
>  					     &src_buf);
>  		if (WARN_ON_ONCE(bytes <= 0))
> -			break;
> +			return;
>  		bytes = min(bytes, (long)(PAGE_SIZE - pg_offset));
>  
>  		memcpy(dst_pages[pg_idx] + pg_offset, src_buf, bytes);
> @@ -1483,6 +1483,7 @@ static void tmc_etr_sync_perf_buffer(struct etr_perf_buffer *etr_perf,
>  		/* Move source pointers */
>  		src_offset += bytes;
>  	}
> +	etr_perf->head = (pg_idx << PAGE_SHIFT) + pg_offset;
>  }
>  
>  /*
> -- 
> 2.25.1
>