[PATCH 1/2] fpga manager: ensure lifetime with of_fpga_mgr_get

[atull]

From: Alan Tull <at...@opensource.altera.com>

Ensure device and driver lifetime from of_fpga_mgr_get() to
fpga_mgr_put().

* Don't put_device() in of_fpga_mgr_get, do it in fpga_mgr_put().
  (still do put_device if there is an error).
* Do module_get on the low level driver.
* Don't need to module_get(THIS_MODULE) since we won't be allowed
  to unload the fpga manager core without unloading low level
  driver first.
* Remove unnedessary null check for node pointer.

Signed-off-by: Alan Tull <at...@opensource.altera.com>
---
 drivers/fpga/fpga-mgr.c |   32 +++++++++++++++++---------------
 1 file changed, 17 insertions(+), 15 deletions(-)

diff --git a/drivers/fpga/fpga-mgr.c b/drivers/fpga/fpga-mgr.c
index 2526163..68d7b41 100644
--- a/drivers/fpga/fpga-mgr.c
+++ b/drivers/fpga/fpga-mgr.c
@@ -204,9 +204,7 @@ struct fpga_manager *of_fpga_mgr_get(struct device_node 
*node)
 {
        struct fpga_manager *mgr;
        struct device *dev;
-
-       if (!node)
-               return ERR_PTR(-EINVAL);
+       int ret = -ENODEV;
 
        dev = class_find_device(fpga_mgr_class, NULL, node,
                                fpga_mgr_of_node_match);
@@ -214,20 +212,25 @@ struct fpga_manager *of_fpga_mgr_get(struct device_node 
*node)
                return ERR_PTR(-ENODEV);
 
        mgr = to_fpga_manager(dev);
-       put_device(dev);
        if (!mgr)
-               return ERR_PTR(-ENODEV);
+               goto err_dev;
 
        /* Get exclusive use of fpga manager */
-       if (!mutex_trylock(&mgr->ref_mutex))
-               return ERR_PTR(-EBUSY);
-
-       if (!try_module_get(THIS_MODULE)) {
-               mutex_unlock(&mgr->ref_mutex);
-               return ERR_PTR(-ENODEV);
+       if (!mutex_trylock(&mgr->ref_mutex)) {
+               ret = -EBUSY;
+               goto err_dev;
        }
 
+       if (!try_module_get(dev->parent->driver->owner))
+               goto err_ll_mod;
+
        return mgr;
+
+err_ll_mod:
+       mutex_unlock(&mgr->ref_mutex);
+err_dev:
+       put_device(dev);
+       return ERR_PTR(ret);
 }
 EXPORT_SYMBOL_GPL(of_fpga_mgr_get);
 
@@ -237,10 +240,9 @@ EXPORT_SYMBOL_GPL(of_fpga_mgr_get);
  */
 void fpga_mgr_put(struct fpga_manager *mgr)
 {
-       if (mgr) {
-               module_put(THIS_MODULE);
-               mutex_unlock(&mgr->ref_mutex);
-       }
+       module_put(mgr->dev.parent->driver->owner);
+       mutex_unlock(&mgr->ref_mutex);
+       put_device(&mgr->dev);
 }
 EXPORT_SYMBOL_GPL(fpga_mgr_put);
 
-- 
1.7.9.5

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