From 56f9bd996902d8e8f83688903bf81ccc5dc4bc7e Mon Sep 17 00:00:00 2001
From: Ben Pfaff <blp@cs.stanford.edu>
Date: Mon, 24 Jul 2006 18:32:38 +0000
Subject: [PATCH] Improvements.
---
ta-advice/HW2 | 27 +++++++++++++++++++++++++++
ta-advice/hw2.txt | 3 +++
2 files changed, 30 insertions(+)
diff --git a/ta-advice/HW2 b/ta-advice/HW2
index 3e9b4ac..7a79395 100644
--- a/ta-advice/HW2
+++ b/ta-advice/HW2
@@ -657,3 +657,30 @@ B11:
Take off points if an answer assumes that there can be more than
one thread per process and doesn't mention that this would be an
extension to the Pintos design.
+
+Check the submitted code, by hand, for the following:
+
+ 1. That the system call handler, which is probably in
+ userprog/syscall.c in syscall_handler(), is reasonably
+ abstracted. It should not all be in one function as one huge
+ switch statement, for example. The code that accesses user
+ memory should be separated into specialized functions. If either
+ of these is not the case, or if the code is otherwise difficult
+ to read, take off points.
+
+ 2. The "Source Code" section in the Introduction to the Pintos
+ manual says, "Update existing comments as you modify code." Most
+ students ignore this. Check whether the comment on
+ process_wait() in process.c has been updated. At a minimum, the
+ two final sentences ("This function will be implemented in
+ problem 2-2. For now, it does nothing.") should have been
+ deleted.
+
+ 3. Find the implementation of the "open" system call. Verify that
+ all resources are released in error cases and that errors are
+ properly handled. One particular problem can be malloc() failure
+ after a file is successfully opened--is the return value checked?
+ If so, is the file closed before returning an error?
+
+ (Failure to check malloc() is in the OVERALL section of the grade
+ report, under DESIGN.)
diff --git a/ta-advice/hw2.txt b/ta-advice/hw2.txt
index f5aab65..f2764a9 100644
--- a/ta-advice/hw2.txt
+++ b/ta-advice/hw2.txt
@@ -101,5 +101,8 @@ PROBLEM 2: SYSTEM CALLS
-5 Added big array (>= 512 bytes) to struct thread without justifying
-10 Added big array (>= 1024 bytes) to struct thread
-5 Superfluous locking on per-thread data structure [which]
+ -10 System call handler is poorly abstracted or unreadable
+ -5 Failed to update comment on process_wait() function after implementing
+ -5 "open" system call fails to release all resources in error cases
Subtotal: /60 (capped at 0)
--
2.30.2