From 85c090982c2a8dd6e236aa8f3d0a79f974ab9603 Mon Sep 17 00:00:00 2001
From: Brian Norris <banorris@uci.edu>
Date: Tue, 3 Jul 2012 16:31:45 -0700
Subject: [PATCH] threads: add per-thread "return" values for
'model-checking/user context' switch
The model-checker needs to return a value to the user context when performing
atomic loads, for instance. I will be implementing this by caching the return
value on a per-thread basis. This is because an atomic_load() might result in a
context switch before actually returning the value.
These functions are not yet used.
---
threads.cc | 4 +++-
threads.h | 22 ++++++++++++++++++++++
2 files changed, 25 insertions(+), 1 deletion(-)
diff --git a/threads.cc b/threads.cc
index 6d290a9..b6eaee4 100644
--- a/threads.cc
+++ b/threads.cc
@@ -69,7 +69,9 @@ void Thread::complete()
}
}
-Thread::Thread(thrd_t *t, void (*func)(void *), void *a) {
+Thread::Thread(thrd_t *t, void (*func)(void *), void *a) :
+ last_action_val(VALUE_NONE)
+{
int ret;
user_thread = t;
diff --git a/threads.h b/threads.h
index a97a04c..ed9cbfe 100644
--- a/threads.h
+++ b/threads.h
@@ -41,6 +41,21 @@ public:
void set_creation(ModelAction *act) { creation = act; }
ModelAction * get_creation() { return creation; }
+ /**
+ * Set a return value for the last action in this thread (e.g., for an
+ * atomic read).
+ * @param value The value to return
+ */
+ void set_return_value(int value) { last_action_val = value; }
+
+ /**
+ * Retrieve a return value for the last action in this thread. Used,
+ * for instance, for an atomic read to return the 'read' value. Should
+ * be called from a user context.
+ * @return The value 'returned' by the action
+ */
+ int get_return_value() { return last_action_val; }
+
friend void thread_startup();
SNAPSHOTALLOC
@@ -56,6 +71,13 @@ private:
thrd_t *user_thread;
thread_id_t id;
thread_state state;
+
+ /**
+ * The value returned by the last action in this thread
+ * @see Thread::set_return_value()
+ * @see Thread::get_return_value()
+ */
+ int last_action_val;
};
Thread * thread_current();
--
2.34.1