[PATCH v5 2/3] coresight: holding cscfg_csdev_lock while removing cscfg from csdev

[Yeoreum Yun]

There'll be possible race scenario for coresight config:

CPU0                                          CPU1
(perf enable)                                 load module
                                              cscfg_load_config_sets()
                                              activate config. // sysfs
                                              (sys_active_cnt == 1)
...
cscfg_csdev_enable_active_config()
  lock(csdev->cscfg_csdev_lock)
                                              deactivate config // sysfs
                                              (sys_activec_cnt == 0)
                                              cscfg_unload_config_sets()
  <iterating config_csdev_list>               cscfg_remove_owned_csdev_configs()
  // here load config activate by CPU1
  unlock(csdev->cscfg_csdev_lock)

iterating config_csdev_list could be raced with config_csdev_list's
entry delete.

To resolve this race , hold csdev->cscfg_csdev_lock() while
cscfg_remove_owned_csdev_configs()

Signed-off-by: Yeoreum Yun <yeoreum.yun at arm.com>
Fixes: 02bd588e12df ("coresight: configuration: Update API to permit dynamic load/unload")
---
 drivers/hwtracing/coresight/coresight-syscfg.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/drivers/hwtracing/coresight/coresight-syscfg.c b/drivers/hwtracing/coresight/coresight-syscfg.c
index a70c1454b410..5d194b9269f5 100644
--- a/drivers/hwtracing/coresight/coresight-syscfg.c
+++ b/drivers/hwtracing/coresight/coresight-syscfg.c
@@ -391,14 +391,17 @@ static void cscfg_owner_put(struct cscfg_load_owner_info *owner_info)
 static void cscfg_remove_owned_csdev_configs(struct coresight_device *csdev, void *load_owner)
 {
 	struct cscfg_config_csdev *config_csdev, *tmp;
+	unsigned long flags;
 
 	if (list_empty(&csdev->config_csdev_list))
 		return;
 
+	raw_spin_lock_irqsave(&csdev->cscfg_csdev_lock, flags);
 	list_for_each_entry_safe(config_csdev, tmp, &csdev->config_csdev_list, node) {
 		if (config_csdev->config_desc->load_owner == load_owner)
 			list_del(&config_csdev->node);
 	}
+	raw_spin_unlock_irqrestore(&csdev->cscfg_csdev_lock, flags);
 }
 
 static void cscfg_remove_owned_csdev_features(struct coresight_device *csdev, void *load_owner)
-- 
LEVI:{C3F47F37-75D8-414A-A8BA-3980EC8A46D7}