Merge branch 'wwan-debugfs'

M Chetan Kumar says:

====================
net: wwan: debugfs dev reference not dropped

This patch series contains WWAN subsystem & IOSM Driver changes to
drop dev reference obtained as part of wwan debugfs dir entry retrieval.

PATCH1: A new debugfs interface is introduced in wwan subsystem so
that wwan driver can drop the obtained dev reference post debugfs use.

PATCH2: IOSM Driver uses new debugfs interface to drop dev reference.

Please refer to commit messages for details.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

4 files changed, 43 insertions, 2 deletions

diff --git a/drivers/net/wwan/iosm/iosm_ipc_debugfs.c b/drivers/net/wwan/iosm/iosm_ipc_debugfs.c
index f2f57751a7d2..e916139b8cd4 100644
--- a/drivers/net/wwan/iosm/iosm_ipc_debugfs.c
+++ b/drivers/net/wwan/iosm/iosm_ipc_debugfs.c
@@ -12,10 +12,10 @@
 
 void ipc_debugfs_init(struct iosm_imem *ipc_imem)
 {
-	struct dentry *debugfs_pdev = wwan_get_debugfs_dir(ipc_imem->dev);
+	ipc_imem->debugfs_wwan_dir = wwan_get_debugfs_dir(ipc_imem->dev);
 
 	ipc_imem->debugfs_dir = debugfs_create_dir(KBUILD_MODNAME,
-						   debugfs_pdev);
+						   ipc_imem->debugfs_wwan_dir);
 
 	ipc_imem->trace = ipc_trace_init(ipc_imem);
 	if (!ipc_imem->trace)
@@ -26,4 +26,5 @@ void ipc_debugfs_deinit(struct iosm_imem *ipc_imem)
 {
 	ipc_trace_deinit(ipc_imem->trace);
 	debugfs_remove_recursive(ipc_imem->debugfs_dir);
+	wwan_put_debugfs_dir(ipc_imem->debugfs_wwan_dir);
 }
diff --git a/drivers/net/wwan/iosm/iosm_ipc_imem.h b/drivers/net/wwan/iosm/iosm_ipc_imem.h
index 5682e8d6be7b..e700dc8bfe0a 100644
--- a/drivers/net/wwan/iosm/iosm_ipc_imem.h
+++ b/drivers/net/wwan/iosm/iosm_ipc_imem.h
@@ -341,6 +341,7 @@ enum ipc_phase {
  * @ev_mux_net_transmit_pending:0 means inform the IPC tasklet to pass
  * @reset_det_n:		Reset detect flag
  * @pcie_wake_n:		Pcie wake flag
+ * @debugfs_wwan_dir:		WWAN Debug FS directory entry
  * @debugfs_dir:		Debug FS directory for driver-specific entries
  */
 struct iosm_imem {
@@ -384,6 +385,7 @@ struct iosm_imem {
 	   reset_det_n:1,
 	   pcie_wake_n:1;
 #ifdef CONFIG_WWAN_DEBUGFS
+	struct dentry *debugfs_wwan_dir;
 	struct dentry *debugfs_dir;
 #endif
 };
diff --git a/drivers/net/wwan/wwan_core.c b/drivers/net/wwan/wwan_core.c
index 1508dc2a497b..b8c7843730ed 100644
--- a/drivers/net/wwan/wwan_core.c
+++ b/drivers/net/wwan/wwan_core.c
@@ -160,6 +160,42 @@ struct dentry *wwan_get_debugfs_dir(struct device *parent)
 	return wwandev->debugfs_dir;
 }
 EXPORT_SYMBOL_GPL(wwan_get_debugfs_dir);
+
+static int wwan_dev_debugfs_match(struct device *dev, const void *dir)
+{
+	struct wwan_device *wwandev;
+
+	if (dev->type != &wwan_dev_type)
+		return 0;
+
+	wwandev = to_wwan_dev(dev);
+
+	return wwandev->debugfs_dir == dir;
+}
+
+static struct wwan_device *wwan_dev_get_by_debugfs(struct dentry *dir)
+{
+	struct device *dev;
+
+	dev = class_find_device(wwan_class, NULL, dir, wwan_dev_debugfs_match);
+	if (!dev)
+		return ERR_PTR(-ENODEV);
+
+	return to_wwan_dev(dev);
+}
+
+void wwan_put_debugfs_dir(struct dentry *dir)
+{
+	struct wwan_device *wwandev = wwan_dev_get_by_debugfs(dir);
+
+	if (WARN_ON(IS_ERR(wwandev)))
+		return;
+
+	/* wwan_dev_get_by_debugfs() also got a reference */
+	put_device(&wwandev->dev);
+	put_device(&wwandev->dev);
+}
+EXPORT_SYMBOL_GPL(wwan_put_debugfs_dir);
 #endif
 
 /* This function allocates and registers a new WWAN device OR if a WWAN device
diff --git a/include/linux/wwan.h b/include/linux/wwan.h
index afb3334ec8c5..5ce2acf444fb 100644
--- a/include/linux/wwan.h
+++ b/include/linux/wwan.h
@@ -174,11 +174,13 @@ void wwan_unregister_ops(struct device *parent);
 
 #ifdef CONFIG_WWAN_DEBUGFS
 struct dentry *wwan_get_debugfs_dir(struct device *parent);
+void wwan_put_debugfs_dir(struct dentry *dir);
 #else
 static inline struct dentry *wwan_get_debugfs_dir(struct device *parent)
 {
 	return ERR_PTR(-ENODEV);
 }
+static inline void wwan_put_debugfs_dir(struct dentry *dir) {}
 #endif
 
 #endif /* __WWAN_H */