Remove trailing white space with:

for f in *.{h,c}; do sed -i .sed 's/[[:blank:]]*$//' $f; done
(Thanks to Nicolás Wolovick)

proc.c

@@ -53,11 +53,11 @@ found:
     return 0;
   }
   sp = p->kstack + KSTACKSIZE;
-  
+
   // Leave room for trap frame.
   sp -= sizeof *p->tf;
   p->tf = (struct trapframe*)sp;
-  
+
   // Set up new context to start executing at forkret,
   // which returns to trapret.
   sp -= 4;
@@ -78,7 +78,7 @@ userinit(void)
 {
   struct proc *p;
   extern char _binary_initcode_start[], _binary_initcode_size[];
-  
+
   acquire(&ptable.lock);
 
   p = allocproc();
@@ -110,7 +110,7 @@ int
 growproc(int n)
 {
   uint sz;
-  
+
   sz = proc->sz;
   if(n > 0){
     if((sz = allocuvm(proc->pgdir, sz, sz + n)) == 0)
@@ -162,13 +162,13 @@ fork(void)
   np->cwd = idup(proc->cwd);
 
   safestrcpy(np->name, proc->name, sizeof(proc->name));
- 
+
   pid = np->pid;
 
   np->state = RUNNABLE;
 
   release(&ptable.lock);
-  
+
   return pid;
 }
 
@@ -342,13 +342,13 @@ forkret(void)
 
   if (first) {
     // Some initialization functions must be run in the context
-    // of a regular process (e.g., they call sleep), and thus cannot 
+    // of a regular process (e.g., they call sleep), and thus cannot
     // be run from main().
     first = 0;
     iinit(ROOTDEV);
     initlog(ROOTDEV);
   }
-  
+
   // Return to "caller", actually trapret (see allocproc).
 }
 
@@ -453,7 +453,7 @@ procdump(void)
   struct proc *p;
   char *state;
   uint pc[10];
-  
+
   for(p = ptable.proc; p < &ptable.proc[NPROC]; p++){
     if(p->state == UNUSED)
       continue;