Re: [PATCH v4 04/10] coresight: tmc: add create/delete functions for etr_buf_node

Hi,

On Fri, 25 Jul 2025 at 11:08, Jie Gan jie.gan@oss.qualcomm.com wrote:

Create and insert or remove the etr_buf_node to/from the etr_buf_list.

Signed-off-by: Jie Gan jie.gan@oss.qualcomm.com

.../hwtracing/coresight/coresight-tmc-etr.c | 65 +++++++++++++++++++ drivers/hwtracing/coresight/coresight-tmc.h | 2 + 2 files changed, 67 insertions(+)

diff --git a/drivers/hwtracing/coresight/coresight-tmc-etr.c b/drivers/hwtracing/coresight/coresight-tmc-etr.c index b07fcdb3fe1a..e8ecb3e087ab 100644 --- a/drivers/hwtracing/coresight/coresight-tmc-etr.c +++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c @@ -1909,6 +1909,71 @@ 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) +{

•   struct etr_buf_node *nd, *next;
  

•   list_for_each_entry_safe(nd, next, &drvdata->etr_buf_list, node) {
  

•           if (nd->sysfs_buf == drvdata->sysfs_buf) {
  

•                   list_del(&nd->node);
  

•                   kfree(nd);
  

•           } else {
  

•                   /* Free allocated buffers which are not utilized by ETR */
  

•                   list_del(&nd->node);
  

•                   tmc_free_etr_buf(nd->sysfs_buf);
  

•                   nd->sysfs_buf = NULL;
  

•                   kfree(nd);
  

•           }
  

•   }
  

+} +EXPORT_SYMBOL_GPL(tmc_clean_etr_buf_list);

+/**

• • tmc_create_etr_buf_node - create a node to store the alloc_buf and
• • insert the node to the etr_buf_list. Create a new buffer if the
• • alloc_buf is NULL.
• • @drvdata: driver data of the TMC device.
• • @alloc_buf: the buffer that is inserted to the list.
• • Return 0 upon success and return the error number if fail.
• */

+int tmc_create_etr_buf_node(struct tmc_drvdata *drvdata, struct etr_buf *alloc_buf)

This list handle function pair look a little asymmetric. Is it not possible to change this to tmc_create_etr_buf_list(struct tmc_drvdata *drvdata, int num_nodes) so that one function creates all the nodes, and another destroys them.

In the logic that decides between using multi buffer or single buffer you can then use a construct such as:

if (single_buffer) drvdata->sysfs_buf = <alloc sysfs buffer> else { tmc_create_etr_buf_list(drvdata, 2); <switch in avail buffer to drvdata->sysfs_buf }

+{

•   struct etr_buf_node *sysfs_buf_node;
  

•   struct etr_buf *sysfs_buf;
  

•   if (!alloc_buf) {
  

•           sysfs_buf = tmc_alloc_etr_buf(drvdata, drvdata->size, 0, cpu_to_node(0), NULL);
  

•           if (IS_ERR(sysfs_buf))
  

•                   return PTR_ERR(sysfs_buf);
  

•   } else
  

•           sysfs_buf = alloc_buf;
  

•   sysfs_buf_node = kzalloc(sizeof(struct etr_buf_node), GFP_KERNEL);
  

•   if (IS_ERR(sysfs_buf_node)) {
  

•           if (!alloc_buf)
  

•                   tmc_free_etr_buf(sysfs_buf);
  

•           return PTR_ERR(sysfs_buf_node);
  

•   }
  

•   sysfs_buf_node->sysfs_buf = sysfs_buf;
  

•   sysfs_buf_node->reading = false;
  

•   if (!alloc_buf)
  

•           sysfs_buf_node->is_free = true;
  

•   else
  

•           sysfs_buf_node->is_free = false;
  

•   list_add(&sysfs_buf_node->node, &drvdata->etr_buf_list);
  

•   return 0;
  

+} +EXPORT_SYMBOL_GPL(tmc_create_etr_buf_node);

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 52ee5f8efe8c..3cb8ba9f88f5 100644 --- a/drivers/hwtracing/coresight/coresight-tmc.h +++ b/drivers/hwtracing/coresight/coresight-tmc.h @@ -461,5 +461,7 @@ void tmc_etr_remove_catu_ops(void); struct etr_buf *tmc_etr_get_buffer(struct coresight_device *csdev, enum cs_mode mode, void *data); extern const struct attribute_group coresight_etr_group; +void tmc_clean_etr_buf_list(struct tmc_drvdata *drvdata); +int tmc_create_etr_buf_node(struct tmc_drvdata *drvdata, struct etr_buf *alloc_buf);

#endif

2.34.1

Regards

Mike