Re: [PATCH v15 2/7] coresight: tmc: add create/clean functions for etr_buf_list
From: Jie Gan
Date: Tue Mar 17 2026 - 21:06:38 EST
On 3/17/2026 7:01 PM, Suzuki K Poulose wrote:
On 13/03/2026 09:02, 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@xxxxxxxxxx>
Signed-off-by: Jie Gan <jie.gan@xxxxxxxxxxxxxxxx>
---
drivers/hwtracing/coresight/coresight-tmc-core.c | 1 +
drivers/hwtracing/coresight/coresight-tmc-etr.c | 108 +++++++++++++ ++++++++++
drivers/hwtracing/coresight/coresight-tmc.h | 17 ++++
3 files changed, 126 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..fdf23e1c932f 100644
--- a/drivers/hwtracing/coresight/coresight-tmc-etr.c
+++ b/drivers/hwtracing/coresight/coresight-tmc-etr.c
@@ -1918,6 +1918,114 @@ 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 unused buffers from @drvdata->etr_buf_list and free them.
+ */
+void tmc_clean_etr_buf_list(struct tmc_drvdata *drvdata)
+{
+ struct etr_buf_node *nd, *next;
+ unsigned long flags;
+
+ lockdep_assert_held(&drvdata->spinlock);
+ list_for_each_entry_safe(nd, next, &drvdata->etr_buf_list, link) {
+ if (nd->sysfs_buf == drvdata->sysfs_buf) {
+ if (coresight_get_mode(drvdata->csdev) != CS_MODE_DISABLED) {
+ /*
+ * Dont free the sysfs_buf, just remove it from list.
+ * drvdata->sysfs_buf will hold the buffer and free it later.
+ */
+ nd->sysfs_buf = NULL;
+ list_del(&nd->link);
+ kfree(nd);
+ continue;
+ }
+ }
+ /* Free allocated buffers which are not utilized by ETR */
+ raw_spin_unlock_irqrestore(&drvdata->spinlock, flags);
This is dangerous ! Restoring the irqflags to an uninitialised value from a different function thant where it was locked. Please clean this up
Noted, will take care of it in the future.
Thanks,
Jie
Suzuki
+ tmc_etr_free_sysfs_buf(nd->sysfs_buf);
+ raw_spin_lock_irqsave(&drvdata->spinlock, flags);
+ drvdata->sysfs_buf = NULL;
+ nd->sysfs_buf = NULL;
+ list_del(&nd->link);
+ kfree(nd);
+ }
+}
+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)
+{
+ struct etr_buf_node *new_node;
+ struct etr_buf *sysfs_buf;
+ unsigned long flags;
+ int i = 0, ret = 0;
+
+ lockdep_assert_held(&drvdata->spinlock);
+ /* We dont need a list if there is only one node */
+ if (num_nodes < 2)
+ return -EINVAL;
+
+ /* We expect that sysfs_buf in drvdata has already been allocated. */
+ if (drvdata->sysfs_buf) {
+ raw_spin_unlock_irqrestore(&drvdata->spinlock, flags);
+ /* Directly insert the allocated sysfs_buf into the list first */
+ new_node = kzalloc_obj(*new_node, GFP_KERNEL);
+ if (IS_ERR(new_node))
+ return PTR_ERR(new_node);
+
+ raw_spin_lock_irqsave(&drvdata->spinlock, flags);
+ new_node->sysfs_buf = drvdata->sysfs_buf;
+ new_node->is_free = false;
+ list_add(&new_node->link, &drvdata->etr_buf_list);
+ i++;
+ }
+
+ raw_spin_unlock_irqrestore(&drvdata->spinlock, flags);
+ while (i < num_nodes) {
+ new_node = kzalloc_obj(*new_node, GFP_KERNEL);
+ if (IS_ERR(new_node)) {
+ ret = PTR_ERR(new_node);
+ break;
+ }
+
+ sysfs_buf = tmc_alloc_etr_buf(drvdata, drvdata->size, 0, cpu_to_node(0), NULL);
+ if (IS_ERR(sysfs_buf)) {
+ kfree(new_node);
+ ret = PTR_ERR(sysfs_buf);
+ break;
+ }
+
+ /* We dont have a available sysfs_buf in drvdata, setup one */
+ if (!drvdata->sysfs_buf) {
+ drvdata->sysfs_buf = sysfs_buf;
+ new_node->is_free = false;
+ } else
+ new_node->is_free = true;
+
+ new_node->sysfs_buf = sysfs_buf;
+ list_add(&new_node->link, &drvdata->etr_buf_list);
+ i++;
+ }
+
+ /* Clean the list if there is an error */
+ if (ret)
+ tmc_clean_etr_buf_list(drvdata);
+
+ raw_spin_lock_irqsave(&drvdata->spinlock, flags);
+
+ return ret;
+}
+EXPORT_SYMBOL_GPL(tmc_create_etr_buf_list);
+
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..81237944b986 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.
+ * @link: list_head of the node.
+ */
+struct etr_buf_node {
+ struct etr_buf *sysfs_buf;
+ bool is_free;
+ loff_t pos;
+ struct list_head link;
+};
+
/**
* 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