staging: wilc1000: Process WARN, INFO options of debug levels from user

This patch enables setting the module's debug options WARN and INFO in the
debugfs file 'wilc_debug_level'.  This functionality allows the user to
enable logging of warnings and other information.  Before this change,
writes to this debugfs file set only one option - DEBUG.  Another option
that is enabled by default is ERR.

As a side effect, this patch removes the 'sparse' warning -
'warning: incorrect type in argument 2 (different address spaces)'.

Signed-off-by: Chandra S Gorentla <csgorentla@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/wilc1000/wilc_debugfs.c

@@ -48,28 +48,19 @@ static ssize_t wilc_debug_level_read(struct file *file, char __user *userbuf, si
 	return simple_read_from_buffer(userbuf, count, ppos, buf, res);
 }
 
-static ssize_t wilc_debug_level_write(struct file *filp, const char *buf, size_t count, loff_t *ppos)
+static ssize_t wilc_debug_level_write(struct file *filp, const char __user *buf,
+					size_t count, loff_t *ppos)
 {
-	char buffer[128] = {};
 	int flag = 0;
+	int ret;
 
-	if (count > sizeof(buffer))
-		return -EINVAL;
-
-	if (copy_from_user(buffer, buf, count)) {
-		return -EFAULT;
-	}
-
-	flag = buffer[0] - '0';
-
-	if (flag > 0)
-		flag = DEBUG | ERR;
-	else if (flag < 0)
-		flag = 100;
+	ret = kstrtouint_from_user(buf, count, 16, &flag);
+	if (ret)
+		return ret;
 
 	if (flag > DBG_LEVEL_ALL) {
 		printk("%s, value (0x%08x) is out of range, stay previous flag (0x%08x)\n", __func__, flag, atomic_read(&DEBUG_LEVEL));
-		return -EFAULT;
+		return -EINVAL;
 	}
 
 	atomic_set(&DEBUG_LEVEL, (int)flag);
@@ -78,6 +69,7 @@ static ssize_t wilc_debug_level_write(struct file *filp, const char *buf, size_t
 		printk("Debug-level disabled\n");
 	else
 		printk("Debug-level enabled\n");
+
 	return count;
 }