[PATCH v11 13/27] coresight: syscfg: Use IRQ-safe spinlock to protect active variables

Leo Yan
2026-05-01T16:48:56Z

cscfg_config_sysfs_get_active_cfg() will be used from idle flows, while
sleeping locks are not allowed. Introduce sysfs_store_lock to replace
the mutex to protect sysfs_active_config and sysfs_active_preset
accesses, with IRQ-safe locking to avoid lockdep complaint.

Refactor cscfg_config_sysfs_activate() to use spinlock for
sysfs_active_config and activate/deactivate config.

Tested-by: Jie Gan <jie.gan@oss.qualcomm.com>
Reviewed-by: Yeoreum Yun <yeoreum.yun@arm.com>
Reviewed-by: James Clark <james.clark@linaro.org>
Tested-by: James Clark <james.clark@linaro.org>
Signed-off-by: Leo Yan <leo.yan@arm.com>
---
drivers/hwtracing/coresight/coresight-syscfg.c | 38 ++++++++++++++------------
drivers/hwtracing/coresight/coresight-syscfg.h | 2 ++
2 files changed, 22 insertions(+), 18 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight-syscfg.c b/drivers/hwtracing/coresight/coresight-syscfg.c
index d7f5037953d6ba7fb7f83a8012a1abc5ffd0a147..2bfdd7b45e49c8bec88428545069577431083bda 100644
--- a/drivers/hwtracing/coresight/coresight-syscfg.c
+++ b/drivers/hwtracing/coresight/coresight-syscfg.c
@@ -953,39 +953,41 @@ int cscfg_config_sysfs_activate(struct cscfg_config_desc *config_desc, bool acti
unsigned long cfg_hash;
int err = 0;

- mutex_lock(&cscfg_mutex);
+ guard(mutex)(&cscfg_mutex);

cfg_hash = (unsigned long)config_desc->event_ea->var;

if (activate) {
/* cannot be a current active value to activate this */
- if (cscfg_mgr->sysfs_active_config) {
- err = -EBUSY;
- goto exit_unlock;
- }
- err = _cscfg_activate_config(cfg_hash);
- if (!err)
+ if (cscfg_mgr->sysfs_active_config)
+ return -EBUSY;
+
+ scoped_guard(raw_spinlock_irqsave, &cscfg_mgr->sysfs_store_lock) {
+ err = _cscfg_activate_config(cfg_hash);
+ if (err)
+ return err;
+
cscfg_mgr->sysfs_active_config = cfg_hash;
+ }
} else {
- /* disable if matching current value */
- if (cscfg_mgr->sysfs_active_config == cfg_hash) {
+ if (cscfg_mgr->sysfs_active_config != cfg_hash)
+ return -EINVAL;
+
+ scoped_guard(raw_spinlock_irqsave, &cscfg_mgr->sysfs_store_lock) {
+ /* disable if matching current value */
_cscfg_deactivate_config(cfg_hash);
cscfg_mgr->sysfs_active_config = 0;
- } else
- err = -EINVAL;
+ }
}

-exit_unlock:
- mutex_unlock(&cscfg_mutex);
- return err;
+ return 0;
}

/* set the sysfs preset value */
void cscfg_config_sysfs_set_preset(int preset)
{
- mutex_lock(&cscfg_mutex);
+ guard(raw_spinlock_irqsave)(&cscfg_mgr->sysfs_store_lock);
cscfg_mgr->sysfs_active_preset = preset;
- mutex_unlock(&cscfg_mutex);
}

/*
@@ -994,10 +996,9 @@ void cscfg_config_sysfs_set_preset(int preset)
*/
void cscfg_config_sysfs_get_active_cfg(unsigned long *cfg_hash, int *preset)
{
- mutex_lock(&cscfg_mutex);
+ guard(raw_spinlock_irqsave)(&cscfg_mgr->sysfs_store_lock);
*preset = cscfg_mgr->sysfs_active_preset;
*cfg_hash = cscfg_mgr->sysfs_active_config;
- mutex_unlock(&cscfg_mutex);
}
EXPORT_SYMBOL_GPL(cscfg_config_sysfs_get_active_cfg);

@@ -1201,6 +1202,7 @@ static int cscfg_create_device(void)
INIT_LIST_HEAD(&cscfg_mgr->load_order_list);
atomic_set(&cscfg_mgr->sys_active_cnt, 0);
cscfg_mgr->load_state = CSCFG_NONE;
+ raw_spin_lock_init(&cscfg_mgr->sysfs_store_lock);

/* setup the device */
dev = cscfg_device();
diff --git a/drivers/hwtracing/coresight/coresight-syscfg.h b/drivers/hwtracing/coresight/coresight-syscfg.h
index 66e2db890d8203853a0c3c907b48aa66dd8014e6..658e93c3705f1cb3ba3523d0bc27ac704697dd70 100644
--- a/drivers/hwtracing/coresight/coresight-syscfg.h
+++ b/drivers/hwtracing/coresight/coresight-syscfg.h
@@ -42,6 +42,7 @@ enum cscfg_load_ops {
* @sysfs_active_config:Active config hash used if CoreSight controlled from sysfs.
* @sysfs_active_preset:Active preset index used if CoreSight controlled from sysfs.
* @load_state: A multi-stage load/unload operation is in progress.
+ * @sysfs_store_lock: Exclusive access sysfs stored variables.
*/
struct cscfg_manager {
struct device dev;
@@ -54,6 +55,7 @@ struct cscfg_manager {
u32 sysfs_active_config;
int sysfs_active_preset;
enum cscfg_load_ops load_state;
+ raw_spinlock_t sysfs_store_lock;
};

/* get reference to dev in cscfg_manager */

--
2.34.1