[PATCH] 6lowpan: no need to check return value of debugfs_create functions

[PATCH] 6lowpan: no need to check return value of debugfs_create functions

[Greg Kroah-Hartman]

When calling debugfs functions, there is no need to ever check the
return value.  The function can work or not, but the code logic should
never do something different based on this.

Because we don't care if debugfs works or not, this trickles back a bit
so we can clean things up by making some functions return void instead
of an error value that is never going to fail.

Cc: Alexander Aring <alex.aring@gmail.com>
Cc: Jukka Rissanen <jukka.rissanen@linux.intel.com>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: linux-bluetooth@vger.kernel.org
Cc: linux-wpan@vger.kernel.org
Cc: netdev@vger.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 net/6lowpan/6lowpan_i.h | 16 ++-----
 net/6lowpan/core.c      |  8 +---
 net/6lowpan/debugfs.c   | 97 +++++++++++------------------------------
 3 files changed, 32 insertions(+), 89 deletions(-)

diff --git a/net/6lowpan/6lowpan_i.h b/net/6lowpan/6lowpan_i.h
index 53cf446ce2e3..01853cec0209 100644
--- a/net/6lowpan/6lowpan_i.h
+++ b/net/6lowpan/6lowpan_i.h
@@ -18,24 +18,16 @@ extern const struct ndisc_ops lowpan_ndisc_ops;
 int addrconf_ifid_802154_6lowpan(u8 *eui, struct net_device *dev);
 
 #ifdef CONFIG_6LOWPAN_DEBUGFS
-int lowpan_dev_debugfs_init(struct net_device *dev);
+void lowpan_dev_debugfs_init(struct net_device *dev);
 void lowpan_dev_debugfs_exit(struct net_device *dev);
 
-int __init lowpan_debugfs_init(void);
+void __init lowpan_debugfs_init(void);
 void lowpan_debugfs_exit(void);
 #else
-static inline int lowpan_dev_debugfs_init(struct net_device *dev)
-{
-	return 0;
-}
-
+static inline void lowpan_dev_debugfs_init(struct net_device *dev) { }
 static inline void lowpan_dev_debugfs_exit(struct net_device *dev) { }
 
-static inline int __init lowpan_debugfs_init(void)
-{
-	return 0;
-}
-
+static inline void __init lowpan_debugfs_init(void) { }
 static inline void lowpan_debugfs_exit(void) { }
 #endif /* CONFIG_6LOWPAN_DEBUGFS */
 
diff --git a/net/6lowpan/core.c b/net/6lowpan/core.c
index 2d68351f1ac4..a068757eabaf 100644
--- a/net/6lowpan/core.c
+++ b/net/6lowpan/core.c
@@ -42,9 +42,7 @@ int lowpan_register_netdevice(struct net_device *dev,
 	if (ret < 0)
 		return ret;
 
-	ret = lowpan_dev_debugfs_init(dev);
-	if (ret < 0)
-		unregister_netdevice(dev);
+	lowpan_dev_debugfs_init(dev);
 
 	return ret;
 }
@@ -152,9 +150,7 @@ static int __init lowpan_module_init(void)
 {
 	int ret;
 
-	ret = lowpan_debugfs_init();
-	if (ret < 0)
-		return ret;
+	lowpan_debugfs_init();
 
 	ret = register_netdevice_notifier(&lowpan_notifier);
 	if (ret < 0) {
diff --git a/net/6lowpan/debugfs.c b/net/6lowpan/debugfs.c
index f5a8eec9d7a3..1c140af06d52 100644
--- a/net/6lowpan/debugfs.c
+++ b/net/6lowpan/debugfs.c
@@ -163,11 +163,11 @@ static const struct file_operations lowpan_ctx_pfx_fops = {
 	.release	= single_release,
 };
 
-static int lowpan_dev_debugfs_ctx_init(struct net_device *dev,
-				       struct dentry *ctx, u8 id)
+static void lowpan_dev_debugfs_ctx_init(struct net_device *dev,
+					struct dentry *ctx, u8 id)
 {
 	struct lowpan_dev *ldev = lowpan_dev(dev);
-	struct dentry *dentry, *root;
+	struct dentry *root;
 	char buf[32];
 
 	WARN_ON_ONCE(id > LOWPAN_IPHC_CTX_TABLE_SIZE);
@@ -175,34 +175,18 @@ static int lowpan_dev_debugfs_ctx_init(struct net_device *dev,
 	sprintf(buf, "%d", id);
 
 	root = debugfs_create_dir(buf, ctx);
-	if (!root)
-		return -EINVAL;
 
-	dentry = debugfs_create_file_unsafe("active", 0644, root,
-					    &ldev->ctx.table[id],
-					    &lowpan_ctx_flag_active_fops);
-	if (!dentry)
-		return -EINVAL;
+	debugfs_create_file("active", 0644, root, &ldev->ctx.table[id],
+			    &lowpan_ctx_flag_active_fops);
 
-	dentry = debugfs_create_file_unsafe("compression", 0644, root,
-					    &ldev->ctx.table[id],
-					    &lowpan_ctx_flag_c_fops);
-	if (!dentry)
-		return -EINVAL;
-
-	dentry = debugfs_create_file("prefix", 0644, root,
-				     &ldev->ctx.table[id],
-				     &lowpan_ctx_pfx_fops);
-	if (!dentry)
-		return -EINVAL;
+	debugfs_create_file("compression", 0644, root, &ldev->ctx.table[id],
+			    &lowpan_ctx_flag_c_fops);
 
-	dentry = debugfs_create_file_unsafe("prefix_len", 0644, root,
-					    &ldev->ctx.table[id],
-					    &lowpan_ctx_plen_fops);
-	if (!dentry)
-		return -EINVAL;
+	debugfs_create_file("prefix", 0644, root, &ldev->ctx.table[id],
+			    &lowpan_ctx_pfx_fops);
 
-	return 0;
+	debugfs_create_file("prefix_len", 0644, root, &ldev->ctx.table[id],
+			    &lowpan_ctx_plen_fops);
 }
 
 static int lowpan_context_show(struct seq_file *file, void *offset)
@@ -242,64 +226,39 @@ static int lowpan_short_addr_get(void *data, u64 *val)
 DEFINE_DEBUGFS_ATTRIBUTE(lowpan_short_addr_fops, lowpan_short_addr_get, NULL,
 			 "0x%04llx\n");
 
-static int lowpan_dev_debugfs_802154_init(const struct net_device *dev,
+static void lowpan_dev_debugfs_802154_init(const struct net_device *dev,
 					  struct lowpan_dev *ldev)
 {
-	struct dentry *dentry, *root;
+	struct dentry *root;
 
 	if (!lowpan_is_ll(dev, LOWPAN_LLTYPE_IEEE802154))
-		return 0;
+		return;
 
 	root = debugfs_create_dir("ieee802154", ldev->iface_debugfs);
-	if (!root)
-		return -EINVAL;
-
-	dentry = debugfs_create_file_unsafe("short_addr", 0444, root,
-					    lowpan_802154_dev(dev)->wdev->ieee802154_ptr,
-					    &lowpan_short_addr_fops);
-	if (!dentry)
-		return -EINVAL;
 
-	return 0;
+	debugfs_create_file("short_addr", 0444, root,
+			    lowpan_802154_dev(dev)->wdev->ieee802154_ptr,
+			    &lowpan_short_addr_fops);
 }
 
-int lowpan_dev_debugfs_init(struct net_device *dev)
+void lowpan_dev_debugfs_init(struct net_device *dev)
 {
 	struct lowpan_dev *ldev = lowpan_dev(dev);
-	struct dentry *contexts, *dentry;
-	int ret, i;
+	struct dentry *contexts;
+	int i;
 
 	/* creating the root */
 	ldev->iface_debugfs = debugfs_create_dir(dev->name, lowpan_debugfs);
-	if (!ldev->iface_debugfs)
-		goto fail;
 
 	contexts = debugfs_create_dir("contexts", ldev->iface_debugfs);
-	if (!contexts)
-		goto remove_root;
-
-	dentry = debugfs_create_file("show", 0644, contexts,
-				     &lowpan_dev(dev)->ctx,
-				     &lowpan_context_fops);
-	if (!dentry)
-		goto remove_root;
-
-	for (i = 0; i < LOWPAN_IPHC_CTX_TABLE_SIZE; i++) {
-		ret = lowpan_dev_debugfs_ctx_init(dev, contexts, i);
-		if (ret < 0)
-			goto remove_root;
-	}
 
-	ret = lowpan_dev_debugfs_802154_init(dev, ldev);
-	if (ret < 0)
-		goto remove_root;
+	debugfs_create_file("show", 0644, contexts, &lowpan_dev(dev)->ctx,
+			    &lowpan_context_fops);
 
-	return 0;
+	for (i = 0; i < LOWPAN_IPHC_CTX_TABLE_SIZE; i++)
+		lowpan_dev_debugfs_ctx_init(dev, contexts, i);
 
-remove_root:
-	lowpan_dev_debugfs_exit(dev);
-fail:
-	return -EINVAL;
+	lowpan_dev_debugfs_802154_init(dev, ldev);
 }
 
 void lowpan_dev_debugfs_exit(struct net_device *dev)
@@ -307,13 +266,9 @@ void lowpan_dev_debugfs_exit(struct net_device *dev)
 	debugfs_remove_recursive(lowpan_dev(dev)->iface_debugfs);
 }
 
-int __init lowpan_debugfs_init(void)
+void __init lowpan_debugfs_init(void)
 {
 	lowpan_debugfs = debugfs_create_dir("6lowpan", NULL);
-	if (!lowpan_debugfs)
-		return -EINVAL;
-
-	return 0;
 }
 
 void lowpan_debugfs_exit(void)
-- 
2.22.0

Re: [PATCH] 6lowpan: no need to check return value of debugfs_create functions

[Jukka Rissanen]

Hi Greg,

Acked-by: Jukka Rissanen <jukka.rissanen@linux.intel.com>

Cheers,
Jukka

On Fri, 2019-06-14 at 09:14 +0200, Greg Kroah-Hartman wrote:
> When calling debugfs functions, there is no need to ever check the
> return value.  The function can work or not, but the code logic
> should
> never do something different based on this.
> 
> Because we don't care if debugfs works or not, this trickles back a
> bit
> so we can clean things up by making some functions return void
> instead
> of an error value that is never going to fail.
> 
> Cc: Alexander Aring <alex.aring@gmail.com>
> Cc: Jukka Rissanen <jukka.rissanen@linux.intel.com>
> Cc: "David S. Miller" <davem@davemloft.net>
> Cc: linux-bluetooth@vger.kernel.org
> Cc: linux-wpan@vger.kernel.org
> Cc: netdev@vger.kernel.org
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> ---
>  net/6lowpan/6lowpan_i.h | 16 ++-----
>  net/6lowpan/core.c      |  8 +---
>  net/6lowpan/debugfs.c   | 97 +++++++++++--------------------------
> ----
>  3 files changed, 32 insertions(+), 89 deletions(-)
> 
> diff --git a/net/6lowpan/6lowpan_i.h b/net/6lowpan/6lowpan_i.h
> index 53cf446ce2e3..01853cec0209 100644
> --- a/net/6lowpan/6lowpan_i.h
> +++ b/net/6lowpan/6lowpan_i.h
> @@ -18,24 +18,16 @@ extern const struct ndisc_ops lowpan_ndisc_ops;
>  int addrconf_ifid_802154_6lowpan(u8 *eui, struct net_device *dev);
>  
>  #ifdef CONFIG_6LOWPAN_DEBUGFS
> -int lowpan_dev_debugfs_init(struct net_device *dev);
> +void lowpan_dev_debugfs_init(struct net_device *dev);
>  void lowpan_dev_debugfs_exit(struct net_device *dev);
>  
> -int __init lowpan_debugfs_init(void);
> +void __init lowpan_debugfs_init(void);
>  void lowpan_debugfs_exit(void);
>  #else
> -static inline int lowpan_dev_debugfs_init(struct net_device *dev)
> -{
> -	return 0;
> -}
> -
> +static inline void lowpan_dev_debugfs_init(struct net_device *dev) {
> }
>  static inline void lowpan_dev_debugfs_exit(struct net_device *dev) {
> }
>  
> -static inline int __init lowpan_debugfs_init(void)
> -{
> -	return 0;
> -}
> -
> +static inline void __init lowpan_debugfs_init(void) { }
>  static inline void lowpan_debugfs_exit(void) { }
>  #endif /* CONFIG_6LOWPAN_DEBUGFS */
>  
> diff --git a/net/6lowpan/core.c b/net/6lowpan/core.c
> index 2d68351f1ac4..a068757eabaf 100644
> --- a/net/6lowpan/core.c
> +++ b/net/6lowpan/core.c
> @@ -42,9 +42,7 @@ int lowpan_register_netdevice(struct net_device
> *dev,
>  	if (ret < 0)
>  		return ret;
>  
> -	ret = lowpan_dev_debugfs_init(dev);
> -	if (ret < 0)
> -		unregister_netdevice(dev);
> +	lowpan_dev_debugfs_init(dev);
>  
>  	return ret;
>  }
> @@ -152,9 +150,7 @@ static int __init lowpan_module_init(void)
>  {
>  	int ret;
>  
> -	ret = lowpan_debugfs_init();
> -	if (ret < 0)
> -		return ret;
> +	lowpan_debugfs_init();
>  
>  	ret = register_netdevice_notifier(&lowpan_notifier);
>  	if (ret < 0) {
> diff --git a/net/6lowpan/debugfs.c b/net/6lowpan/debugfs.c
> index f5a8eec9d7a3..1c140af06d52 100644
> --- a/net/6lowpan/debugfs.c
> +++ b/net/6lowpan/debugfs.c
> @@ -163,11 +163,11 @@ static const struct file_operations
> lowpan_ctx_pfx_fops = {
>  	.release	= single_release,
>  };
>  
> -static int lowpan_dev_debugfs_ctx_init(struct net_device *dev,
> -				       struct dentry *ctx, u8 id)
> +static void lowpan_dev_debugfs_ctx_init(struct net_device *dev,
> +					struct dentry *ctx, u8 id)
>  {
>  	struct lowpan_dev *ldev = lowpan_dev(dev);
> -	struct dentry *dentry, *root;
> +	struct dentry *root;
>  	char buf[32];
>  
>  	WARN_ON_ONCE(id > LOWPAN_IPHC_CTX_TABLE_SIZE);
> @@ -175,34 +175,18 @@ static int lowpan_dev_debugfs_ctx_init(struct
> net_device *dev,
>  	sprintf(buf, "%d", id);
>  
>  	root = debugfs_create_dir(buf, ctx);
> -	if (!root)
> -		return -EINVAL;
>  
> -	dentry = debugfs_create_file_unsafe("active", 0644, root,
> -					    &ldev->ctx.table[id],
> -					    &lowpan_ctx_flag_active_fop
> s);
> -	if (!dentry)
> -		return -EINVAL;
> +	debugfs_create_file("active", 0644, root, &ldev->ctx.table[id],
> +			    &lowpan_ctx_flag_active_fops);
>  
> -	dentry = debugfs_create_file_unsafe("compression", 0644, root,
> -					    &ldev->ctx.table[id],
> -					    &lowpan_ctx_flag_c_fops);
> -	if (!dentry)
> -		return -EINVAL;
> -
> -	dentry = debugfs_create_file("prefix", 0644, root,
> -				     &ldev->ctx.table[id],
> -				     &lowpan_ctx_pfx_fops);
> -	if (!dentry)
> -		return -EINVAL;
> +	debugfs_create_file("compression", 0644, root, &ldev-
> >ctx.table[id],
> +			    &lowpan_ctx_flag_c_fops);
>  
> -	dentry = debugfs_create_file_unsafe("prefix_len", 0644, root,
> -					    &ldev->ctx.table[id],
> -					    &lowpan_ctx_plen_fops);
> -	if (!dentry)
> -		return -EINVAL;
> +	debugfs_create_file("prefix", 0644, root, &ldev->ctx.table[id],
> +			    &lowpan_ctx_pfx_fops);
>  
> -	return 0;
> +	debugfs_create_file("prefix_len", 0644, root, &ldev-
> >ctx.table[id],
> +			    &lowpan_ctx_plen_fops);
>  }
>  
>  static int lowpan_context_show(struct seq_file *file, void *offset)
> @@ -242,64 +226,39 @@ static int lowpan_short_addr_get(void *data,
> u64 *val)
>  DEFINE_DEBUGFS_ATTRIBUTE(lowpan_short_addr_fops,
> lowpan_short_addr_get, NULL,
>  			 "0x%04llx\n");
>  
> -static int lowpan_dev_debugfs_802154_init(const struct net_device
> *dev,
> +static void lowpan_dev_debugfs_802154_init(const struct net_device
> *dev,
>  					  struct lowpan_dev *ldev)
>  {
> -	struct dentry *dentry, *root;
> +	struct dentry *root;
>  
>  	if (!lowpan_is_ll(dev, LOWPAN_LLTYPE_IEEE802154))
> -		return 0;
> +		return;
>  
>  	root = debugfs_create_dir("ieee802154", ldev->iface_debugfs);
> -	if (!root)
> -		return -EINVAL;
> -
> -	dentry = debugfs_create_file_unsafe("short_addr", 0444, root,
> -					    lowpan_802154_dev(dev)-
> >wdev->ieee802154_ptr,
> -					    &lowpan_short_addr_fops);
> -	if (!dentry)
> -		return -EINVAL;
>  
> -	return 0;
> +	debugfs_create_file("short_addr", 0444, root,
> +			    lowpan_802154_dev(dev)->wdev-
> >ieee802154_ptr,
> +			    &lowpan_short_addr_fops);
>  }
>  
> -int lowpan_dev_debugfs_init(struct net_device *dev)
> +void lowpan_dev_debugfs_init(struct net_device *dev)
>  {
>  	struct lowpan_dev *ldev = lowpan_dev(dev);
> -	struct dentry *contexts, *dentry;
> -	int ret, i;
> +	struct dentry *contexts;
> +	int i;
>  
>  	/* creating the root */
>  	ldev->iface_debugfs = debugfs_create_dir(dev->name,
> lowpan_debugfs);
> -	if (!ldev->iface_debugfs)
> -		goto fail;
>  
>  	contexts = debugfs_create_dir("contexts", ldev->iface_debugfs);
> -	if (!contexts)
> -		goto remove_root;
> -
> -	dentry = debugfs_create_file("show", 0644, contexts,
> -				     &lowpan_dev(dev)->ctx,
> -				     &lowpan_context_fops);
> -	if (!dentry)
> -		goto remove_root;
> -
> -	for (i = 0; i < LOWPAN_IPHC_CTX_TABLE_SIZE; i++) {
> -		ret = lowpan_dev_debugfs_ctx_init(dev, contexts, i);
> -		if (ret < 0)
> -			goto remove_root;
> -	}
>  
> -	ret = lowpan_dev_debugfs_802154_init(dev, ldev);
> -	if (ret < 0)
> -		goto remove_root;
> +	debugfs_create_file("show", 0644, contexts, &lowpan_dev(dev)-
> >ctx,
> +			    &lowpan_context_fops);
>  
> -	return 0;
> +	for (i = 0; i < LOWPAN_IPHC_CTX_TABLE_SIZE; i++)
> +		lowpan_dev_debugfs_ctx_init(dev, contexts, i);
>  
> -remove_root:
> -	lowpan_dev_debugfs_exit(dev);
> -fail:
> -	return -EINVAL;
> +	lowpan_dev_debugfs_802154_init(dev, ldev);
>  }
>  
>  void lowpan_dev_debugfs_exit(struct net_device *dev)
> @@ -307,13 +266,9 @@ void lowpan_dev_debugfs_exit(struct net_device
> *dev)
>  	debugfs_remove_recursive(lowpan_dev(dev)->iface_debugfs);
>  }
>  
> -int __init lowpan_debugfs_init(void)
> +void __init lowpan_debugfs_init(void)
>  {
>  	lowpan_debugfs = debugfs_create_dir("6lowpan", NULL);
> -	if (!lowpan_debugfs)
> -		return -EINVAL;
> -
> -	return 0;
>  }
>  
>  void lowpan_debugfs_exit(void)

Re: [PATCH] 6lowpan: no need to check return value of debugfs_create functions

[Marcel Holtmann]

Hi Greg,

> When calling debugfs functions, there is no need to ever check the
> return value.  The function can work or not, but the code logic should
> never do something different based on this.
> 
> Because we don't care if debugfs works or not, this trickles back a bit
> so we can clean things up by making some functions return void instead
> of an error value that is never going to fail.
> 
> Cc: Alexander Aring <alex.aring@gmail.com>
> Cc: Jukka Rissanen <jukka.rissanen@linux.intel.com>
> Cc: "David S. Miller" <davem@davemloft.net>
> Cc: linux-bluetooth@vger.kernel.org
> Cc: linux-wpan@vger.kernel.org
> Cc: netdev@vger.kernel.org
> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
> ---
> net/6lowpan/6lowpan_i.h | 16 ++-----
> net/6lowpan/core.c      |  8 +---
> net/6lowpan/debugfs.c   | 97 +++++++++++------------------------------
> 3 files changed, 32 insertions(+), 89 deletions(-)

patch has been applied to bluetooth-next tree.

Regards

Marcel