stm class: Fix unbalanced module/device refcounting

[firefly-linux-kernel-4.4.55.git] / drivers / hwtracing / stm / core.c

diff --git a/drivers/hwtracing/stm/core.c b/drivers/hwtracing/stm/core.c
index 41fee197ed314fb548a8c12e865306abd2298d29..31a03e2fae29119494f955f10cb44d5bda3d38e0 100644 (file)
--- a/drivers/hwtracing/stm/core.c
+++ b/drivers/hwtracing/stm/core.c
@@ -113,6 +113,7 @@ struct stm_device *stm_find_device(const char *buf)
 
        stm = to_stm_device(dev);
        if (!try_module_get(stm->owner)) {
+               /* matches class_find_device() above */
                put_device(dev);
                return NULL;
        }
@@ -125,7 +126,7 @@ struct stm_device *stm_find_device(const char *buf)
  * @stm:       stm device, previously acquired by stm_find_device()
  *
  * This drops the module reference and device reference taken by
- * stm_find_device().
+ * stm_find_device() or stm_char_open().
  */
 void stm_put_device(struct stm_device *stm)
 {
@@ -365,6 +366,8 @@ static int stm_char_open(struct inode *inode, struct file *file)
        return nonseekable_open(inode, file);
 
 err_free:
+       /* matches class_find_device() above */
+       put_device(dev);
        kfree(stmf);
 
        return err;
@@ -375,6 +378,11 @@ static int stm_char_release(struct inode *inode, struct file *file)
        struct stm_file *stmf = file->private_data;
 
        stm_output_free(stmf->stm, &stmf->output);
+
+       /*
+        * matches the stm_char_open()'s
+        * class_find_device() + try_module_get()
+        */
        stm_put_device(stmf->stm);
        kfree(stmf);
 
@@ -539,10 +547,8 @@ static int stm_char_policy_set_ioctl(struct stm_file *stmf, void __user *arg)
                ret = stm->data->link(stm->data, stmf->output.master,
                                      stmf->output.channel);
 
-       if (ret) {
+       if (ret)
                stm_output_free(stmf->stm, &stmf->output);
-               stm_put_device(stmf->stm);
-       }
 
 err_free:
        kfree(id);
@@ -679,6 +685,7 @@ int stm_register_device(struct device *parent, struct stm_data *stm_data,
        return 0;
 
 err_device:
+       /* matches device_initialize() above */
        put_device(&stm->dev);
 err_free:
        kfree(stm);
@@ -791,7 +798,6 @@ static int stm_source_link_add(struct stm_source_device *src,
 
 fail_free_output:
        stm_output_free(stm, &src->output);
-       stm_put_device(stm);
 
 fail_detach:
        mutex_lock(&stm->link_mutex);
@@ -905,8 +911,10 @@ static ssize_t stm_source_link_store(struct device *dev,
                return -EINVAL;
 
        err = stm_source_link_add(src, link);
-       if (err)
+       if (err) {
+               /* matches the stm_find_device() above */
                stm_put_device(link);
+       }
 
        return err ? : count;
 }