When coresight device is in an active session, driver module of
that device should not be removed. Use try_get_module() in
coresight_grab_device() to prevent module to be unloaded.
Use get_device()/put_device() to protect device data
in the middle of active session.

Signed-off-by: Tingwei Zhang <redacted>
---
 drivers/hwtracing/coresight/coresight.c | 39 +++++++++++++++++++++----
 1 file changed, 34 insertions(+), 5 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight.c b/drivers/hwtracing/coresight/coresight.c
index b7151c5f81b1..1626bc885dfe 100644
--- a/drivers/hwtracing/coresight/coresight.c
+++ b/drivers/hwtracing/coresight/coresight.c

@@ -640,7 +640,7 @@ struct coresight_device *coresight_get_sink_by_id(u32 id)
  * don't appear on the trace path, they should be handled along with the
  * the master device.
  */
-static void coresight_grab_device(struct coresight_device *csdev)
+static int coresight_grab_device(struct coresight_device *csdev)
 {
        int i;

@@ -648,10 +648,30 @@ static void coresight_grab_device(struct coresight_device *csdev)
                struct coresight_device *child;

                child  = csdev->pdata->conns[i].child_dev;
-               if (child && child->type == CORESIGHT_DEV_TYPE_HELPER)
+               if (child && child->type == CORESIGHT_DEV_TYPE_HELPER) {
+                       if (!try_module_get(child->dev.parent->driver->owner))
+                               goto err;
+                       get_device(child->dev.parent);
                        pm_runtime_get_sync(child->dev.parent);
+               }
        }
+       if (!try_module_get(csdev->dev.parent->driver->owner))
+               goto err;
+       get_device(csdev->dev.parent);
        pm_runtime_get_sync(csdev->dev.parent);
+       return 0;
+err:
+       for (i--; i >= 0; i--) {
+               struct coresight_device *child;
+
+               child  = csdev->pdata->conns[i].child_dev;
+               if (child && child->type == CORESIGHT_DEV_TYPE_HELPER) {
+                       pm_runtime_put(child->dev.parent);
+                       put_device(child->dev.parent);
+                       module_put(child->dev.parent->driver->owner);
+               }
+       }
+       return -ENODEV;
 }

 /*

@@ -663,12 +683,17 @@ static void coresight_drop_device(struct coresight_device *csdev)
        int i;

        pm_runtime_put(csdev->dev.parent);
+       put_device(csdev->dev.parent);
+       module_put(csdev->dev.parent->driver->owner);
        for (i = 0; i < csdev->pdata->nr_outport; i++) {
                struct coresight_device *child;

                child  = csdev->pdata->conns[i].child_dev;
-               if (child && child->type == CORESIGHT_DEV_TYPE_HELPER)
+               if (child && child->type == CORESIGHT_DEV_TYPE_HELPER) {
                        pm_runtime_put(child->dev.parent);
+                       put_device(child->dev.parent);
+                       module_put(child->dev.parent->driver->owner);
+               }
        }
 }

@@ -687,7 +712,7 @@ static int _coresight_build_path(struct coresight_device *csdev,
                                 struct coresight_device *sink,
                                 struct list_head *path)
 {
-       int i;
+       int i, ret;
        bool found = false;
        struct coresight_node *node;

@@ -721,7 +746,11 @@ static int _coresight_build_path(struct coresight_device *csdev,
        if (!node)
                return -ENOMEM;

-       coresight_grab_device(csdev);
+       ret = coresight_grab_device(csdev);
+       if (ret) {
+               kfree(node);
+               return ret;
+       }
        node->csdev = csdev;
        list_add(&node->link, path);

--

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