ixgbe: eliminate Smatch warnings in ixgbe_debugfs.c

This patch replaces calls to copy_to_user, copy_from_user, and the associated
logic, with calls to simple_read_from_buffer and simple_write_to_buffer
respectively.  This was done to eliminate warnings generated by the Smatch
static analysis tool.

v2- Fix return values based community feedback

Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
CC: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Josh Hay <joshua.a.hay@intel.com>
Tested-by: Phil Schmitt <phillip.j.schmitt@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

1 files changed, 46 insertions, 37 deletions

diff --git a/drivers/net/ethernet/intel/ixgbe/ixgbe_debugfs.c b/drivers/net/ethernet/intel/ixgbe/ixgbe_debugfs.c
index efaf9a73cc79..50aa546b8c7a 100644
--- a/drivers/net/ethernet/intel/ixgbe/ixgbe_debugfs.c
+++ b/drivers/net/ethernet/intel/ixgbe/ixgbe_debugfs.c
@@ -47,23 +47,27 @@ static ssize_t ixgbe_dbg_reg_ops_read(struct file *filp, char __user *buffer,
                                     size_t count, loff_t *ppos)
 {
         struct ixgbe_adapter *adapter = filp->private_data;
-        char buf[256];
-        int bytes_not_copied;
+        char *buf;
         int len;
 
         /* don't allow partial reads */
         if (*ppos != 0)
                 return 0;
 
-        len = snprintf(buf, sizeof(buf), "%s: %s\n",
-                       adapter->netdev->name, ixgbe_dbg_reg_ops_buf);
-        if (count < len)
+        buf = kasprintf(GFP_KERNEL, "%s: %s\n",
+                        adapter->netdev->name,
+                        ixgbe_dbg_reg_ops_buf);
+        if (!buf)
+                return -ENOMEM;
+
+        if (count < strlen(buf)) {
+                kfree(buf);
                 return -ENOSPC;
-        bytes_not_copied = copy_to_user(buffer, buf, len);
-        if (bytes_not_copied < 0)
-                return bytes_not_copied;
+        }
+
+        len = simple_read_from_buffer(buffer, count, ppos, buf, strlen(buf));
 
-        *ppos = len;
+        kfree(buf);
         return len;
 }
 
@@ -79,7 +83,7 @@ static ssize_t ixgbe_dbg_reg_ops_write(struct file *filp,
                                      size_t count, loff_t *ppos)
 {
         struct ixgbe_adapter *adapter = filp->private_data;
-        int bytes_not_copied;
+        int len;
 
         /* don't allow partial writes */
         if (*ppos != 0)
@@ -87,14 +91,15 @@ static ssize_t ixgbe_dbg_reg_ops_write(struct file *filp,
         if (count >= sizeof(ixgbe_dbg_reg_ops_buf))
                 return -ENOSPC;
 
-        bytes_not_copied = copy_from_user(ixgbe_dbg_reg_ops_buf, buffer, count);
-        if (bytes_not_copied < 0)
-                return bytes_not_copied;
-        else if (bytes_not_copied < count)
-                count -= bytes_not_copied;
-        else
-                return -ENOSPC;
-        ixgbe_dbg_reg_ops_buf[count] = '\0';
+        len = simple_write_to_buffer(ixgbe_dbg_reg_ops_buf,
+                                     sizeof(ixgbe_dbg_reg_ops_buf)-1,
+                                     ppos,
+                                     buffer,
+                                     count);
+        if (len < 0)
+                return len;
+
+        ixgbe_dbg_reg_ops_buf[len] = '\0';
 
         if (strncmp(ixgbe_dbg_reg_ops_buf, "write", 5) == 0) {
                 u32 reg, value;
@@ -147,23 +152,27 @@ static ssize_t ixgbe_dbg_netdev_ops_read(struct file *filp,
                                          size_t count, loff_t *ppos)
 {
         struct ixgbe_adapter *adapter = filp->private_data;
-        char buf[256];
-        int bytes_not_copied;
+        char *buf;
         int len;
 
         /* don't allow partial reads */
         if (*ppos != 0)
                 return 0;
 
-        len = snprintf(buf, sizeof(buf), "%s: %s\n",
-                       adapter->netdev->name, ixgbe_dbg_netdev_ops_buf);
-        if (count < len)
+        buf = kasprintf(GFP_KERNEL, "%s: %s\n",
+                        adapter->netdev->name,
+                        ixgbe_dbg_netdev_ops_buf);
+        if (!buf)
+                return -ENOMEM;
+
+        if (count < strlen(buf)) {
+                kfree(buf);
                 return -ENOSPC;
-        bytes_not_copied = copy_to_user(buffer, buf, len);
-        if (bytes_not_copied < 0)
-                return bytes_not_copied;
+        }
+
+        len = simple_read_from_buffer(buffer, count, ppos, buf, strlen(buf));
 
-        *ppos = len;
+        kfree(buf);
         return len;
 }
 
@@ -179,7 +188,7 @@ static ssize_t ixgbe_dbg_netdev_ops_write(struct file *filp,
                                           size_t count, loff_t *ppos)
 {
         struct ixgbe_adapter *adapter = filp->private_data;
-        int bytes_not_copied;
+        int len;
 
         /* don't allow partial writes */
         if (*ppos != 0)
@@ -187,15 +196,15 @@ static ssize_t ixgbe_dbg_netdev_ops_write(struct file *filp,
         if (count >= sizeof(ixgbe_dbg_netdev_ops_buf))
                 return -ENOSPC;
 
-        bytes_not_copied = copy_from_user(ixgbe_dbg_netdev_ops_buf,
-                                          buffer, count);
-        if (bytes_not_copied < 0)
-                return bytes_not_copied;
-        else if (bytes_not_copied < count)
-                count -= bytes_not_copied;
-        else
-                return -ENOSPC;
-        ixgbe_dbg_netdev_ops_buf[count] = '\0';
+        len = simple_write_to_buffer(ixgbe_dbg_netdev_ops_buf,
+                                     sizeof(ixgbe_dbg_netdev_ops_buf)-1,
+                                     ppos,
+                                     buffer,
+                                     count);
+        if (len < 0)
+                return len;
+
+        ixgbe_dbg_netdev_ops_buf[len] = '\0';
 
         if (strncmp(ixgbe_dbg_netdev_ops_buf, "tx_timeout", 10) == 0) {
                 adapter->netdev->netdev_ops->ndo_tx_timeout(adapter->netdev);