To support dynamically enabling and disabling the CoreSight path during CPU idle, cscfg_config_sysfs_get_active_cfg() may be called by the ETM driver in an atomic context. However, the function currently acquires a mutex, which is a sleepable lock, and this is not allowed in atomic context.
To make cscfg_config_sysfs_get_active_cfg() called in the idle flow, replace the mutex with a raw spinlock to protect the active variables.
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 | 22 +++++++++++++--------- drivers/hwtracing/coresight/coresight-syscfg.h | 2 ++ 2 files changed, 15 insertions(+), 9 deletions(-)
diff --git a/drivers/hwtracing/coresight/coresight-syscfg.c b/drivers/hwtracing/coresight/coresight-syscfg.c index 6836b05986e8091b4f8ad7d082d6a016f8cf7d74..53aa1a44f9ac8f65b4e3cce06a33255abfc17351 100644 --- a/drivers/hwtracing/coresight/coresight-syscfg.c +++ b/drivers/hwtracing/coresight/coresight-syscfg.c @@ -957,15 +957,19 @@ int cscfg_config_sysfs_activate(struct cscfg_config_desc *config_desc, bool acti
cfg_hash = (unsigned long)config_desc->event_ea->var;
+ raw_spin_lock(&cscfg_mgr->spinlock); + if (activate) { + /* cannot be a current active value to activate this */ if (cscfg_mgr->sysfs_active_config) { err = -EBUSY; - goto exit_unlock; + } else { + err = _cscfg_activate_config(cfg_hash); + if (!err) + cscfg_mgr->sysfs_active_config = cfg_hash; } - err = _cscfg_activate_config(cfg_hash); - if (!err) - cscfg_mgr->sysfs_active_config = cfg_hash; + } else { /* disable if matching current value */ if (cscfg_mgr->sysfs_active_config == cfg_hash) { @@ -975,7 +979,8 @@ int cscfg_config_sysfs_activate(struct cscfg_config_desc *config_desc, bool acti err = -EINVAL; }
-exit_unlock: + raw_spin_unlock(&cscfg_mgr->spinlock); + mutex_unlock(&cscfg_mutex); return err; } @@ -983,9 +988,8 @@ int cscfg_config_sysfs_activate(struct cscfg_config_desc *config_desc, bool acti /* set the sysfs preset value */ void cscfg_config_sysfs_set_preset(int preset) { - mutex_lock(&cscfg_mutex); + guard(raw_spinlock)(&cscfg_mgr->spinlock); cscfg_mgr->sysfs_active_preset = preset; - mutex_unlock(&cscfg_mutex); }
/* @@ -994,10 +998,9 @@ 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)(&cscfg_mgr->spinlock); *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 +1204,7 @@ 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->spinlock);
/* setup the device */ dev = cscfg_device(); diff --git a/drivers/hwtracing/coresight/coresight-syscfg.h b/drivers/hwtracing/coresight/coresight-syscfg.h index 66e2db890d8203853a0c3c907b48aa66dd8014e6..f52aba4608dadc1c7666e0e28c9b43dc1c33d1eb 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. + * @spinlock: Exclusive access sysfs_active_* 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 spinlock; };
/* get reference to dev in cscfg_manager */