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.

Signed-off-by: Tingwei Zhang <redacted>
---
 drivers/hwtracing/coresight/coresight.c | 27 +++++++++++++++++++++----
 1 file changed, 23 insertions(+), 4 deletions(-)

diff --git a/drivers/hwtracing/coresight/coresight.c b/drivers/hwtracing/coresight/coresight.c
index b7151c5f81b1..17bc76ea86ae 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 +648,25 @@ 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;
                        pm_runtime_get_sync(child->dev.parent);
+               }
        }
+       if (!try_module_get(csdev->dev.parent->driver->owner))
+               goto err;
        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);
+       }
+       return -ENODEV;
 }

 /*

@@ -663,12 +678,15 @@ static void coresight_drop_device(struct coresight_device *csdev)
        int i;

        pm_runtime_put(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);
+                       module_put(child->dev.parent->driver->owner);
+               }
        }
 }

@@ -721,7 +739,8 @@ static int _coresight_build_path(struct coresight_device *csdev,
        if (!node)
                return -ENOMEM;

-       coresight_grab_device(csdev);
+       if (coresight_grab_device(csdev))
+               return -ENODEV;
        node->csdev = csdev;
        list_add(&node->link, path);

--

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