Re: [PATCH v14 2/7] coresight: tmc: add create/clean functions for etr_buf_list

[Suzuki K Poulose <suzuki.poulose@arm.com>]

On 09/03/2026 09:47, Jie Gan wrote:
> Introduce functions for creating and inserting or removing the
> etr_buf_node to/from the etr_buf_list.
> 
> The byte-cntr functionality requires two etr_buf to receive trace data.
> The active etr_buf collects the trace data from source device, while the
> byte-cntr reading function accesses the deactivated etr_buf after is
> has been filled and synced, transferring data to the userspace.
> 
> Reviewed-by: Mike Leach <mike.leach@linaro.org>
> Signed-off-by: Jie Gan <jie.gan@oss.qualcomm.com>
> ---
>   drivers/hwtracing/coresight/coresight-tmc-core.c |  1 +
>   drivers/hwtracing/coresight/coresight-tmc-etr.c  | 94 ++++++++++++++++++++++++
>   drivers/hwtracing/coresight/coresight-tmc.h      | 17 +++++
>   3 files changed, 112 insertions(+)
> 
> diff --git a/drivers/hwtracing/coresight/coresight-tmc-core.c b/drivers/hwtracing/coresight/coresight-tmc-core.c
> index c89fe996af23..bac3278ef4dd 100644
> --- a/drivers/hwtracing/coresight/coresight-tmc-core.c
> +++ b/drivers/hwtracing/coresight/coresight-tmc-core.c
> @@ -835,6 +835,7 @@ static int __tmc_probe(struct device *dev, struct resource *res)
>   		idr_init(&drvdata->idr);
>   		mutex_init(&drvdata->idr_mutex);
>   		dev_list = "tmc_etr";
> +		INIT_LIST_HEAD(&drvdata->etr_buf_list);
>   		break;
>   	case TMC_CONFIG_TYPE_ETF:
>   		desc.groups = coresight_etf_groups;
> diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c
> index 4dc1defe27a5..15c0874ff641 100644
> --- a/drivers/hwtracing/coresight/coresight-tmc-etr.c
> +++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c
> @@ -1918,6 +1918,100 @@ const struct coresight_ops tmc_etr_cs_ops = {
>   	.panic_ops	= &tmc_etr_sync_ops,
>   };
>   
> +/**
> + * tmc_clean_etr_buf_list - clean the etr_buf_list.
> + * @drvdata:	driver data of the TMC device.
> + *
> + * Remove the allocated node from the list and free the extra buffer.
> + */
> +void tmc_clean_etr_buf_list(struct tmc_drvdata *drvdata)
> +{
...

> +}
> +EXPORT_SYMBOL_GPL(tmc_clean_etr_buf_list);
> +
> +/**
> + * tmc_create_etr_buf_list - create a list to manage the etr_buf_node.
> + * @drvdata:	driver data of the TMC device.
> + * @num_nodes:	number of nodes want to create with the list.
> + *
> + * Return 0 upon success and return the error number if fail.
> + */
> +int tmc_create_etr_buf_list(struct tmc_drvdata *drvdata, int num_nodes)
> +{

...


> +EXPORT_SYMBOL_GPL(tmc_create_etr_buf_list);

Given the above functions are "EXPORTED" please could you make sure that
the locking requirements are documented and asserted (lockdep_assert)
in the functions ?


Suzuki


> +
>   int tmc_read_prepare_etr(struct tmc_drvdata *drvdata)
>   {
>   	int ret = 0;
> diff --git a/drivers/hwtracing/coresight/coresight-tmc.h b/drivers/hwtracing/coresight/coresight-tmc.h
> index 319a354ede9f..5ac07e8dd5ff 100644
> --- a/drivers/hwtracing/coresight/coresight-tmc.h
> +++ b/drivers/hwtracing/coresight/coresight-tmc.h
> @@ -208,6 +208,19 @@ struct tmc_resrv_buf {
>   	s64		len;
>   };
>   
> +/**
> + * @sysfs_buf:	Allocated sysfs_buf.
> + * @is_free:	Indicates whether the buffer is free to choose.
> + * @pos:	Position of the buffer.
> + * @node:	Node in etr_buf_list.
> + */
> +struct etr_buf_node {
> +	struct etr_buf		*sysfs_buf;
> +	bool			is_free;
> +	loff_t			pos;
> +	struct list_head	node;
> +};
> +
>   /**
>    * struct tmc_drvdata - specifics associated to an TMC component
>    * @atclk:	optional clock for the core parts of the TMC.
> @@ -245,6 +258,7 @@ struct tmc_resrv_buf {
>    *		(after crash) by default.
>    * @crash_mdata: Reserved memory for storing tmc crash metadata.
>    *		 Used by ETR/ETF.
> + * @etr_buf_list: List that is used to manage allocated etr_buf.
>    */
>   struct tmc_drvdata {
>   	struct clk		*atclk;
> @@ -275,6 +289,7 @@ struct tmc_drvdata {
>   	struct etr_buf		*perf_buf;
>   	struct tmc_resrv_buf	resrv_buf;
>   	struct tmc_resrv_buf	crash_mdata;
> +	struct list_head        etr_buf_list;
>   };
>   
>   struct etr_buf_operations {
> @@ -447,5 +462,7 @@ struct etr_buf *tmc_etr_get_buffer(struct coresight_device *csdev,
>   				   enum cs_mode mode,
>   				   struct coresight_path *path);
>   extern const struct attribute_group coresight_etr_group;
> +void tmc_clean_etr_buf_list(struct tmc_drvdata *drvdata);
> +int tmc_create_etr_buf_list(struct tmc_drvdata *drvdata, int num_nodes);
>   
>   #endif
>