use simple_read_from_buffer in kernel/

Cleanup using simple_read_from_buffer() for /dev/cpuset/tasks and
/proc/config.gz.

Cc: Paul Jackson <pj@sgi.com>
Cc: Randy Dunlap <rdunlap@xenotime.net>
Signed-off-by: NAkinobu Mita <akinobu.mita@gmail.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

kernel/configs.c

@@ -61,18 +61,9 @@ static ssize_t
 ikconfig_read_current(struct file *file, char __user *buf,
 		      size_t len, loff_t * offset)
 {
-	loff_t pos = *offset;
-	ssize_t count;
-
-	if (pos >= kernel_config_data_size)
-		return 0;
-
-	count = min(len, (size_t)(kernel_config_data_size - pos));
-	if (copy_to_user(buf, kernel_config_data + MAGIC_SIZE + pos, count))
-		return -EFAULT;
-
-	*offset += count;
-	return count;
+	return simple_read_from_buffer(buf, len, offset,
+				       kernel_config_data + MAGIC_SIZE,
+				       kernel_config_data_size);
 }
 
 static const struct file_operations ikconfig_file_ops = {

kernel/cpuset.c

@@ -1772,12 +1772,7 @@ static ssize_t cpuset_tasks_read(struct file *file, char __user *buf,
 {
 	struct ctr_struct *ctr = file->private_data;
 
-	if (*ppos + nbytes > ctr->bufsz)
-		nbytes = ctr->bufsz - *ppos;
-	if (copy_to_user(buf, ctr->buf + *ppos, nbytes))
-		return -EFAULT;
-	*ppos += nbytes;
-	return nbytes;
+	return simple_read_from_buffer(buf, nbytes, ppos, ctr->buf, ctr->bufsz);
 }
 
 static int cpuset_tasks_release(struct inode *unused_inode, struct file *file)