linux-kernel - [PATCH] dmascc: Return correct error codes

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Message-ID: <20160209184236.GA23644@amitoj-Inspiron-3542>
Date:	Wed, 10 Feb 2016 00:12:36 +0530
From:	Amitoj Kaur Chawla <amitoj1606@...il.com>
To:	jreuter@...na.de, linux-hams@...r.kernel.org,
	netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:	julia.lawall@...6.fr
Subject: [PATCH] dmascc: Return correct error codes

This change has been made with the goal that kernel functions should
return something more descriptive than -1 on failure.

A variable `err` has been introduced for storing error codes.

The return value of kzalloc on failure should return a -1 and not a
-ENOMEM. This was found using Coccinelle. A simplified version of
the semantic patch used is:

//<smpl>
@@
expression *e;
identifier l1;
@@

e = kzalloc(...);
if (e == NULL) {
...
goto l1;
}
l1:
...
return -1
+ -ENOMEM
;
//</smpl

Furthermore, set `err` to -ENOMEM on failure of alloc_netdev(), and to
-ENODEV on failure of register_netdev() and probe_irq_off().

The single call site only checks that the return value is not 0,
hence no change is required at the call site.

Signed-off-by: Amitoj Kaur Chawla <amitoj1606@...il.com>
---
Not sure if -ENODEV is the right error code for probe_irq_off(irqs),
since there are few other examples with this function.

 drivers/net/hamradio/dmascc.c | 13 ++++++++++---
 1 file changed, 10 insertions(+), 3 deletions(-)

diff --git a/drivers/net/hamradio/dmascc.c b/drivers/net/hamradio/dmascc.c
index c3d3777..e4137c1 100644
--- a/drivers/net/hamradio/dmascc.c
+++ b/drivers/net/hamradio/dmascc.c
@@ -451,7 +451,7 @@ static const struct net_device_ops scc_netdev_ops = {
 
 static int __init setup_adapter(int card_base, int type, int n)
 {
-	int i, irq, chip;
+	int i, irq, chip, err;
 	struct scc_info *info;
 	struct net_device *dev;
 	struct scc_priv *priv;
@@ -463,14 +463,17 @@ static int __init setup_adapter(int card_base, int type, int n)
 
 	/* Initialize what is necessary for write_scc and write_scc_data */
 	info = kzalloc(sizeof(struct scc_info), GFP_KERNEL | GFP_DMA);
-	if (!info)
+	if (!info) {
+		err = -ENOMEM;
 		goto out;
+	}
 
 	info->dev[0] = alloc_netdev(0, "", NET_NAME_UNKNOWN, dev_setup);
 	if (!info->dev[0]) {
 		printk(KERN_ERR "dmascc: "
 		       "could not allocate memory for %s at %#3x\n",
 		       hw[type].name, card_base);
+		err = -ENOMEM;
 		goto out1;
 	}
 
@@ -479,6 +482,7 @@ static int __init setup_adapter(int card_base, int type, int n)
 		printk(KERN_ERR "dmascc: "
 		       "could not allocate memory for %s at %#3x\n",
 		       hw[type].name, card_base);
+		err = -ENOMEM;
 		goto out2;
 	}
 	spin_lock_init(&info->register_lock);
@@ -549,6 +553,7 @@ static int __init setup_adapter(int card_base, int type, int n)
 		printk(KERN_ERR
 		       "dmascc: could not find irq of %s at %#3x (irq=%d)\n",
 		       hw[type].name, card_base, irq);
+		err = -ENODEV;
 		goto out3;
 	}
 
@@ -585,11 +590,13 @@ static int __init setup_adapter(int card_base, int type, int n)
 	if (register_netdev(info->dev[0])) {
 		printk(KERN_ERR "dmascc: could not register %s\n",
 		       info->dev[0]->name);
+		err = -ENODEV;
 		goto out3;
 	}
 	if (register_netdev(info->dev[1])) {
 		printk(KERN_ERR "dmascc: could not register %s\n",
 		       info->dev[1]->name);
+		err = -ENODEV;
 		goto out4;
 	}
 
@@ -612,7 +619,7 @@ static int __init setup_adapter(int card_base, int type, int n)
       out1:
 	kfree(info);
       out:
-	return -1;
+	return err;
 }
 
 
-- 
1.9.1