[PATCH] proc: sysctl: add _proc_do_string helper

The logic in proc_do_string is worth re-using without passing in a
ctl_table structure (say, we want to calculate a pointer and pass that in
instead); pass in the two fields it uses from that structure as explicit
arguments.

Signed-off-by: Sam Vilain <sam.vilain@catalyst.net.nz>
Cc: Serge E. Hallyn <serue@us.ibm.com>
Cc: Kirill Korotaev <dev@openvz.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Herbert Poetzl <herbert@13thfloor.at>
Cc: Andrey Savochkin <saw@sw.ru>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

kernel/sysctl.c

@@ -1624,6 +1624,55 @@ static ssize_t proc_writesys(struct file * file, const char __user * buf,
 	return do_rw_proc(1, file, (char __user *) buf, count, ppos);
 }
 
+int _proc_do_string(void* data, int maxlen, int write, struct file *filp,
+		    void __user *buffer, size_t *lenp, loff_t *ppos)
+{
+	size_t len;
+	char __user *p;
+	char c;
+	
+	if (!data || !maxlen || !*lenp ||
+	    (*ppos && !write)) {
+		*lenp = 0;
+		return 0;
+	}
+	
+	if (write) {
+		len = 0;
+		p = buffer;
+		while (len < *lenp) {
+			if (get_user(c, p++))
+				return -EFAULT;
+			if (c == 0 || c == '\n')
+				break;
+			len++;
+		}
+		if (len >= maxlen)
+			len = maxlen-1;
+		if(copy_from_user(data, buffer, len))
+			return -EFAULT;
+		((char *) data)[len] = 0;
+		*ppos += *lenp;
+	} else {
+		len = strlen(data);
+		if (len > maxlen)
+			len = maxlen;
+		if (len > *lenp)
+			len = *lenp;
+		if (len)
+			if(copy_to_user(buffer, data, len))
+				return -EFAULT;
+		if (len < *lenp) {
+			if(put_user('\n', ((char __user *) buffer) + len))
+				return -EFAULT;
+			len++;
+		}
+		*lenp = len;
+		*ppos += len;
+	}
+	return 0;
+}
+
 /**
  * proc_dostring - read a string sysctl
  * @table: the sysctl table
@@ -1645,50 +1694,8 @@ static ssize_t proc_writesys(struct file * file, const char __user * buf,
 int proc_dostring(ctl_table *table, int write, struct file *filp,
 		  void __user *buffer, size_t *lenp, loff_t *ppos)
 {
-	size_t len;
-	char __user *p;
-	char c;
-	
-	if (!table->data || !table->maxlen || !*lenp ||
-	    (*ppos && !write)) {
-		*lenp = 0;
-		return 0;
-	}
-	
-	if (write) {
-		len = 0;
-		p = buffer;
-		while (len < *lenp) {
-			if (get_user(c, p++))
-				return -EFAULT;
-			if (c == 0 || c == '\n')
-				break;
-			len++;
-		}
-		if (len >= table->maxlen)
-			len = table->maxlen-1;
-		if(copy_from_user(table->data, buffer, len))
-			return -EFAULT;
-		((char *) table->data)[len] = 0;
-		*ppos += *lenp;
-	} else {
-		len = strlen(table->data);
-		if (len > table->maxlen)
-			len = table->maxlen;
-		if (len > *lenp)
-			len = *lenp;
-		if (len)
-			if(copy_to_user(buffer, table->data, len))
-				return -EFAULT;
-		if (len < *lenp) {
-			if(put_user('\n', ((char __user *) buffer) + len))
-				return -EFAULT;
-			len++;
-		}
-		*lenp = len;
-		*ppos += len;
-	}
-	return 0;
+	return _proc_do_string(table->data, table->maxlen, write, filp,
+			       buffer, lenp, ppos);
 }
 
 /*