. fixed a recently introduced scheduler (run-queue) bug in proc.c

. a little (optional) debugging code added to proc.c and associated
  data in proc.h

diff --git a/kernel/proc.c b/kernel/proc.c
index b103ff2c7611031814f475ba4585e5b9cc3ef54d..14ab629ea686cad0950432ec67cfc5842d16d1a4 100755 (executable)
--- a/kernel/proc.c
+++ b/kernel/proc.c
@@ -415,6 +415,13 @@ register struct proc *rp;  /* this process is now runnable */
 /* Add 'rp' to one of the queues of runnable processes.  */
   int q = rp->p_priority;      /* scheduling queue to use */
 
+#if ENABLE_K_DEBUGGING
+  if(rp->p_ready) {
+       kprintf("ready() already ready process\n", NO_NUM);
+  }
+  rp->p_ready = 1;
+#endif
+
   /* Processes, in principle, are added to the end of the queue. However, 
    * user processes are added in front of the queue, because this is a bit 
    * fairer to I/O bound processes. 
@@ -453,6 +460,13 @@ register struct proc *rp;  /* this process is no longer runnable */
   register struct proc **qtail;        /* queue's rdy_tail */
   int q = rp->p_priority;              /* queue to use */
 
+#if ENABLE_K_DEBUGGING
+  if(!rp->p_ready) {
+       kprintf("unready() already unready process\n", NO_NUM);
+  }
+  rp->p_ready = 0;
+#endif
+
   /* Side-effect for tasks: check if the task's stack still is ok? */
   if (istaskp(rp)) {                           
        if (*rp->p_stguard != STACK_GUARD)
@@ -468,16 +482,19 @@ register struct proc *rp; /* this process is no longer runnable */
           rdy_head[q] = xp->p_nextready;       /* new head of queue */
           if (rp == proc_ptr)                  /* current process removed */
               pick_proc();                     /* pick new process to run */
-      } 
+       if(rp == rdy_tail[q])
+               rdy_tail[q] = NIL_PROC;
+      }
       else {                                   /* check body of queue */
           while (xp->p_nextready != rp)                /* stop if process is next */
               if ( (xp = xp->p_nextready) == NIL_PROC) 
                   return;      
           xp->p_nextready = xp->p_nextready->p_nextready;
           if (rdy_tail[q] == rp)               /* possibly update tail */
-              rdy_tail[q] = rp;
+              rdy_tail[q] = xp;
       }
   }
+
 }
 
 /*===========================================================================*

diff --git a/kernel/proc.h b/kernel/proc.h
index 0c0b7b27da1c52efda26a37d2d4133dc2c43c7e4..9c71895eb5d2c4e0e4ebbb616880a708ccfbd881 100755 (executable)
--- a/kernel/proc.h
+++ b/kernel/proc.h
@@ -62,6 +62,10 @@ struct proc {
   unsigned p_pendcount;                /* count of pending and unfinished signals */
 
   char p_name[PROC_NAME_LEN];  /* name of the process, including \0 */
+
+#if ENABLE_K_DEBUGGING
+  int p_ready, p_found;
+#endif
 };
 
 /* Guard word for task stacks. */