[PATCH 2/2] coresight: core: fix memory leak in dict->fwnode_list

[Junhao He]

There are memory leaks reported by kmemleak:
...
unreferenced object 0xffff2020103c3200 (size 256):
  comm "insmod", pid 4476, jiffies 4294978252 (age 50072.536s)
  hex dump (first 32 bytes):
    10 60 40 06 28 20 ff ff 10 c0 59 06 20 20 ff ff  .`@.( ....Y.  ..
    10 e0 47 06 28 20 ff ff 10 00 49 06 28 20 ff ff  ..G.( ....I.( ..
  backtrace:
    [<0000000034ec4724>] __kmem_cache_alloc_node+0x2f8/0x348
    [<0000000057fbc15d>] __kmalloc_node_track_caller+0x5c/0x110
    [<00000055d5e34b>] krealloc+0x8c/0x178
    [<00000000a4635beb>] coresight_alloc_device_name+0x128/0x188 [coresight]
    [<00000000a92ddfee>] funnel_cs_ops+0x10/0xfffffffffffedaa0 [coresight_funnel]
    [<00000000449e20f8>] dynamic_funnel_ids+0x80/0xfffffffffffed840 [coresight_funnel]
...

when remove driver, the golab variables defined by the macro
DEFINE_CORESIGHT_DEVLIST will be released, dict->nr_idx and
dict->fwnode_list are cleared to 0. The lifetime of the golab
variable has ended. So the buffer pointer is lost.

Use the callback of devm_add_action_or_reset() to free memory.

Fixes: 0f5f9b6ba9e1 ("coresight: Use platform agnostic names")
Signed-off-by: Junhao He <hejunhao3 at huawei.com>
---
 drivers/hwtracing/coresight/coresight-core.c | 20 +++++++++++++++++++-
 1 file changed, 19 insertions(+), 1 deletion(-)

diff --git a/drivers/hwtracing/coresight/coresight-core.c b/drivers/hwtracing/coresight/coresight-core.c
index 9fabe00a40d6..6849faad697d 100644
--- a/drivers/hwtracing/coresight/coresight-core.c
+++ b/drivers/hwtracing/coresight/coresight-core.c
@@ -1756,6 +1756,20 @@ bool coresight_loses_context_with_cpu(struct device *dev)
 }
 EXPORT_SYMBOL_GPL(coresight_loses_context_with_cpu);
 
+void coresight_release_dev_list(void *data)
+{
+	struct coresight_dev_list *dict = data;
+
+	mutex_lock(&coresight_mutex);
+
+	if (dict->nr_idx) {
+		kfree(dict->fwnode_list);
+		dict->nr_idx = 0;
+	}
+
+	mutex_unlock(&coresight_mutex);
+}
+
 /*
  * coresight_alloc_device_name - Get an index for a given device in the
  * device index list specific to a driver. An index is allocated for a
@@ -1766,12 +1780,16 @@ EXPORT_SYMBOL_GPL(coresight_loses_context_with_cpu);
 char *coresight_alloc_device_name(struct coresight_dev_list *dict,
 				  struct device *dev)
 {
-	int idx;
+	int idx, ret;
 	char *name = NULL;
 	struct fwnode_handle **list;
 
 	mutex_lock(&coresight_mutex);
 
+	ret = devm_add_action_or_reset(dev, coresight_release_dev_list, dict);
+	if (ret)
+		goto done;
+
 	idx = coresight_search_device_idx(dict, dev_fwnode(dev));
 	if (idx < 0) {
 		/* Make space for the new entry */
-- 
2.33.0