[PATCH] Uml: first part rework of run_helper() and users.

With Jeff Dike <jdike@addtoit.com>,

Fixed a file descriptor leak in the network driver when changing an IP
address.

Fixed the error handling in run_helper.

Paolo notes:

Actually, this is part one of the change, the exact one extracted from Jeff
Dike's incrementals tree before 2.6.9-rc big UML merge.

There is some changes must be done, so I'm also sending a second patch with
this one, too.  Separated for tracking purposes.
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade_spam@yahoo.it>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/um/drivers/net_user.c

@@ -173,8 +173,9 @@ static int change_tramp(char **argv, char *output, int output_len)
 	pe_data.stdout = fds[1];
 	pid = run_helper(change_pre_exec, &pe_data, argv, NULL);
 
-	os_close_file(fds[1]);
 	read_output(fds[0], output, output_len);
+	os_close_file(fds[0]);
+	os_close_file(fds[1]);
 
 	CATCH_EINTR(err = waitpid(pid, NULL, 0));
 	return(pid);

arch/um/kernel/helper.c

@@ -94,24 +94,20 @@ int run_helper(void (*pre_exec)(void *), void *pre_data, char **argv,
 	if(n < 0){
 		printk("run_helper : read on pipe failed, err = %d\n", -n);
 		err = n;
-		goto out_kill;
+		os_kill_process(pid, 1);
 	}
 	else if(n != 0){
 		CATCH_EINTR(n = waitpid(pid, NULL, 0));
 		pid = -errno;
 	}
+	err = pid;
 
-	if(stack_out == NULL) free_stack(stack, 0);
-        else *stack_out = stack;
-	return(pid);
-
- out_kill:
-	os_kill_process(pid, 1);
  out_close:
 	os_close_file(fds[0]);
-	os_close_file(fds[1]);
  out_free:
-	free_stack(stack, 0);
+	if(stack_out == NULL)
+		free_stack(stack, 0);
+        else *stack_out = stack;
 	return(err);
 }