[PATCH v15 2/7] coresight: tmc: add create/clean functions for etr_buf_list
Suzuki K Poulose
suzuki.poulose at arm.com
Tue Mar 17 04:01:16 PDT 2026
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 at linaro.org>
> Signed-off-by: Jie Gan <jie.gan at oss.qualcomm.com>
> ---
> 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
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
>
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