From b83118bb4a39f5a8540c1f776e0af0420737afd0 Mon Sep 17 00:00:00 2001
From: =?utf8?q?Martin=20Ho=C5=99e=C5=88ovsk=C3=BD?=
 <Martin.Horenovsky@gmail.com>
Date: Mon, 16 Sep 2013 16:30:15 +0200
Subject: [PATCH] Cosmetic changes to load.c, load.h. Adds and cleans up
 comments.

---
 rtems/gw/libs/load.c | 33 ++++++++++++++++++++-------------
 rtems/gw/libs/load.h | 30 +++++++++++++++++++++++++++++-
 2 files changed, 49 insertions(+), 14 deletions(-)

diff --git a/rtems/gw/libs/load.c b/rtems/gw/libs/load.c
index ba7fac4..6afb7a9 100644
--- a/rtems/gw/libs/load.c
+++ b/rtems/gw/libs/load.c
@@ -1,11 +1,3 @@
-/*
-* Implements simple producer/consumer thread pair to cause load on the CPU.
-* 
-* Used in benchmarking the CAN gateway.
-*
-* Co-opted from http://support.dce.felk.cvut.cz/pos/cv3/src/semaphore.html. 
-*/
-
 #include <stdio.h>
 
 #include <pthread.h>
@@ -13,7 +5,7 @@
 
 #include "load.h"
 
-
+/* Load function for threads. */
 static void* produce(void* arg);
 static void* consume(void* arg);
 
@@ -27,7 +19,7 @@ static char running = 0;
 static void* produce(void* arg){
     while (1) {
             sem_wait(&consumed);
-            n++;  /* increment n by 1 */
+            n++; 
             sem_post(&produced);
             pthread_testcancel();
     }
@@ -37,13 +29,20 @@ static void* produce(void* arg){
 static void* consume(void* arg){
     while (1) {
             sem_wait(&produced);
-            n--; /* aaand decrement */
+            n--;
             sem_post(&consumed);
             pthread_testcancel();
     }
     return NULL;
 }
 
+/*
+* This function starts threads loading the CPU and creates associated semaphores. 
+* 
+* Has a guard to prevent starting again, before it was stopped.
+*
+* No error handling currently, only tries to report errors.
+*/
 int start_thread_load(){
     if (running == 0){
         printf("Attempting to start load.\n");
@@ -84,9 +83,10 @@ int start_thread_load(){
 
 /*
 * This function stops threads loading the CPU and destroys associated semaphores. 
+*
+* Has a guard against attempting to stop the threads if they are not running.
 * 
 * No error handling currently, only tries to report errors.
-* 
 */
 int end_thread_load(){
     if (running == 1){
@@ -94,15 +94,22 @@ int end_thread_load(){
         printf("Attempting to cancel producer thread.\n");
         res = pthread_cancel(producer);
         if (res != 0){
+            /* This means that sending cancel signal has failed... Just returning an error should be enough. */
+            /* If we killed the thread, destroying the semaphore would lead to UB. */
             printf("Failed.\n");
-            /* Not sure what to do with error here, will have to figure out later. */
+            return 1;
         }
+
         printf("Attempting to cancel consumer thread.\n");
         res = pthread_cancel(consumer);
         if (res != 0){
+            /* Same here. */
             printf("Failed.\n");
+            return 1;
         }
+
         printf("Preparing to destroy semaphores.\n");
+        /* Wait a bit so that the threads can get to a cancellation point. */
         sleep(1);
         sem_destroy(&produced);
         sem_destroy(&consumed);
diff --git a/rtems/gw/libs/load.h b/rtems/gw/libs/load.h
index b355c24..1cb6af9 100644
--- a/rtems/gw/libs/load.h
+++ b/rtems/gw/libs/load.h
@@ -1,7 +1,35 @@
+/*
+* Implements simple producer/consumer thread pair to cause load on the CPU.
+* 
+* Used in benchmarking the CAN gateway.
+*
+* Co-opted from http://support.dce.felk.cvut.cz/pos/cv3/src/semaphore.html. 
+*/
 #ifndef __CPU_LOAD_H_
 #define __CPU_LOAD_H_
 
+
+/*
+* This function starts threads loading the CPU and creates associated semaphores. 
+* 
+* Has a guard to prevent starting again, before it was stopped.
+*
+* No error handling currently, only tries to report errors.
+*
+* 0 if successfull, 1 otherwise.
+*/
 int start_thread_load();
+
+/*
+* This function stops threads loading the CPU and destroys associated semaphores. 
+*
+* Has a guard against attempting to stop the threads if they are not running.
+* 
+* No error handling currently, only tries to report errors.
+*
+* 0 if successfull, 1 otherwise.
+*/
 int end_thread_load();
 
-#endif
\ No newline at end of file
+#endif
+
-- 
2.39.2