clean up stale error checks and panics

delete unused functions
a few comments

Notes

@@ -95,49 +95,15 @@ inode->count counts in-memory pointers to the struct
 blocks and inodes have ad-hoc sleep-locks
   provide a single mechanism?
 
-test 14-character file names
-and file arguments longer than 14
-
 kalloc() can return 0; do callers handle this right?
 
-OH! recursive interrupts will use up any amount of cpu[].stack!
-  underflow and wrecks *previous* cpu's struct
-
-disk scheduling
-mkdir
-sh arguments
-sh redirection
-indirect blocks
-is there a create/create race for same file name?
-  resulting in two entries w/ same name in directory?
-why does shell often ignore first line of input?
-
 test: one process unlinks a file while another links to it
 test: one process opens a file while another deletes it
-test: mkdir. deadlock d/.. vs ../d, two processes.
+test: deadlock d/.. vs ../d, two processes.
 test: dup() shared fd->off
 test: sbrk
 test: does echo foo > x truncate x?
 
-make proc[0] runnable
-cpu early tss and gdt
-how do we get cpu0 scheduler() to use mpstack, not proc[0].kstack?
-when iget() first sleeps, where does it longjmp to?
-maybe set up proc[0] to be runnable, with entry proc0main(), then
-  have main() call scheduler()?
-  perhaps so proc[0] uses right kstack?
-  and scheduler() uses mpstack?
-ltr sets the busy bit in the TSS, faults if already set
-  so gdt and TSS per cpu?
-  we don't want to be using some random process's gdt when it changes it.
-maybe get rid of per-proc gdt and ts
-  one per cpu
-  refresh it when needed
-  setupsegs(proc *)
-
-why do we get 0 characters from keyboard?
-are the locks in the right place in keyboardintr?
-
 sh: support pipes?  leave it for the class?
 sh: dynamic memory allocation?
 sh: should sh support ; () &  --- need malloc
@@ -146,3 +112,11 @@ sh: stop stdin on ctrl-d (for cat > y)
 really should have bdwrite() for file content
   and make some inode updates async
   so soft updates make sense
+
+disk scheduling
+echo foo > bar should truncate bar
+  so O_CREATE should not truncate
+  but O_TRUNC should
+
+make it work on one cpu
+make it work on amsterdam

console.c

@@ -9,10 +9,6 @@ struct spinlock console_lock;
 int panicked = 0;
 int use_console_lock = 0;
 
-// per-cpu copy of output to help panic/lock debugging
-char obuf[NCPU][1024];
-uint obufi[NCPU];
-
 /*
  * copy console output to parallel port, which you can tell
  * .bochsrc to copy to the stdout:
@@ -37,10 +33,6 @@ cons_putc(int c)
   ushort *crt = (ushort *) 0xB8000; // base of CGA memory
   int ind;
 
-  obuf[rcr4()][obufi[rcr4()]++] = c;
-  if(obufi[rcr4()] >= 1024)
-    obufi[rcr4()] = 0;
-
   if(panicked){
     cli();
     for(;;)

defs.h

@@ -16,7 +16,7 @@ struct jmpbuf;
 void setupsegs(struct proc *);
 struct proc * copyproc(struct proc*);
 struct spinlock;
-char *growproc(int);
+int growproc(int);
 void sleep(void *, struct spinlock *);
 void wakeup(void *);
 void scheduler(void);

main.c

@@ -25,8 +25,6 @@ main0(void)
   int i;
   struct proc *p;
 
-  lcr4(0); // xxx copy of cpu #
-
   // clear BSS
   memset(edata, 0, end - edata);
 
@@ -97,8 +95,6 @@ main0(void)
 void
 mpmain(void)
 {
-  lcr4(1); // xxx copy of cpu #
-
   cprintf("cpu%d: starting\n", cpu());
   idtinit(); // CPU's idt
   if(cpu() == 0)

param.h

@@ -1,10 +1,10 @@
-#define NPROC 64
-#define PAGE 4096
-#define KSTACKSIZE PAGE
-#define NCPU 8
-#define NOFILE 16 // file descriptors per process
-#define NFD 100 // file descriptors per system
-#define NREQUEST 100 // outstanding disk requests
-#define NBUF 10
-#define NINODE 100
-#define NDEV 10
+#define NPROC 64        // maximum number of processes
+#define PAGE 4096       // granularity of user-space memory allocation
+#define KSTACKSIZE PAGE // size of per-process kernel stack
+#define NCPU 8          // maximum number of CPUs
+#define NOFILE 16       // file descriptors per process
+#define NFD 100         // file descriptors per system
+#define NREQUEST 100    // outstanding disk requests
+#define NBUF 10         // size of disk block cache
+#define NINODE 100      // maximum number of active i-nodes
+#define NDEV 10         // maximum major device number

proc.c

@@ -138,22 +138,22 @@ copyproc(struct proc* p)
   return np;
 }
 
-char *
+int
 growproc(int n)
 {
   struct proc *cp = curproc[cpu()];
   char *newmem, *oldmem;
 
   newmem = kalloc(cp->sz + n);
-  if(newmem == 0) return (char *) -1;
+  if(newmem == 0)
+    return -1;
   memmove(newmem, cp->mem, cp->sz);
   memset(newmem + cp->sz, 0, n);
   oldmem = cp->mem;
   cp->mem = newmem;
   kfree(oldmem, cp->sz);
-  cprintf("growproc: added %d bytes to %d bytes\n", n, cp->sz);
   cp->sz += n;
-  return cp->sz - n;
+  return 0;
 }
 
 // Per-CPU process scheduler. 

spinlock.c

@@ -6,18 +6,11 @@
 #include "proc.h"
 #include "spinlock.h"
 
-// Can't call cprintf from inside these routines,
-// because cprintf uses them itself.
-//#define cprintf dont_use_cprintf
-
-#define LOCKMAGIC 0x6673ffea
-
 extern int use_console_lock;
 
 void
 initlock(struct spinlock *lock, char *name)
 {
-  lock->magic = LOCKMAGIC;
   lock->name = name;
   lock->locked = 0;
   lock->cpu = 0xffffffff;
@@ -38,43 +31,39 @@ getcallerpcs(void *v, uint pcs[])
 void
 acquire(struct spinlock * lock)
 {
-  if(lock->magic != LOCKMAGIC)
-    panic("weird lock magic");
   if(holding(lock))
     panic("acquire");
 
   if(cpus[cpu()].nlock == 0)
     cli();
   cpus[cpu()].nlock++;
 
-	while(cmpxchg(0, 1, &lock->locked) == 1)
-		;
-	cpuid(0, 0, 0, 0, 0);	// memory barrier
-	getcallerpcs(&lock, lock->pcs);
-	lock->cpu = cpu() + 10;
-        cpus[cpu()].lastacquire = lock;
+  while(cmpxchg(0, 1, &lock->locked) == 1)
+    ;
+  cpuid(0, 0, 0, 0, 0);	// memory barrier
+  getcallerpcs(&lock, lock->pcs);
+  lock->cpu = cpu() + 10;
+  cpus[cpu()].lastacquire = lock;
 }
 
 void
 release(struct spinlock * lock)
 {
-  if(lock->magic != LOCKMAGIC)
-    panic("weird lock magic");
 
-	if(!holding(lock))
-		panic("release");
+  if(!holding(lock))
+    panic("release");
 
-        cpus[cpu()].lastrelease = lock;
-        lock->pcs[0] = 0;
-        lock->cpu = 0xffffffff;
-	cpuid(0, 0, 0, 0, 0);	// memory barrier
-	lock->locked = 0;
-	if(--cpus[cpu()].nlock == 0)
-		sti();
+  cpus[cpu()].lastrelease = lock;
+  lock->pcs[0] = 0;
+  lock->cpu = 0xffffffff;
+  cpuid(0, 0, 0, 0, 0);	// memory barrier
+  lock->locked = 0;
+  if(--cpus[cpu()].nlock == 0)
+    sti();
 }
 
 int
 holding(struct spinlock *lock)
 {
-	return lock->locked && lock->cpu == cpu() + 10;
+  return lock->locked && lock->cpu == cpu() + 10;
 }

spinlock.h

@@ -1,5 +1,4 @@
 struct spinlock {
-  uint magic;
   char *name;
   uint locked;
   int cpu;

syscall.c

@@ -473,15 +473,15 @@ sys_getpid(void)
 int
 sys_sbrk(void)
 {
-  char *r;
   int n;
   struct proc *cp = curproc[cpu()];
 
   if(fetcharg(0, &n) < 0)
     return -1;
-  r = growproc(n);
+  if(growproc(n) != 0)
+    return -1;
   setupsegs(cp);  
-  return (int) r;
+  return 0;
 }
 
 int

trap.c

@@ -34,59 +34,19 @@ void
 trap(struct trapframe *tf)
 {
   int v = tf->trapno;
-
-  if(cpus[cpu()].nlock){
-    cprintf("trap v %d eip %x cpu %d nlock %d\n",
-            v, tf->eip, cpu(), cpus[cpu()].nlock);
-    panic("interrupt while holding a lock");
-  }
-
-  if(curproc[cpu()] == 0){
-    if(&tf < cpus[cpu()].mpstack || &tf > cpus[cpu()].mpstack + MPSTACK){
-      cprintf("&tf %x mpstack %x\n", &tf, cpus[cpu()].mpstack);
-      panic("trap cpu stack");
-    }
-  } else if(curproc[cpu()]){
-    if(&tf < curproc[cpu()]->kstack){
-      panic("trap kstack");
-    }
-  }
 
   if(v == T_SYSCALL){
     struct proc *cp = curproc[cpu()];
     int num = cp->tf->eax;
-    if((read_eflags() & FL_IF) == 0)
-      panic("syscall but interrupts now disabled");
-    if(cp == 0)
-      panic("syscall with no proc");
     if(cp->killed)
       proc_exit();
     cp->tf = tf;
     syscall();
-    if(cp != curproc[cpu()])
-      panic("trap ret wrong curproc");
-    if(cp->state != RUNNING)
-      panic("trap ret but not RUNNING");
-    if(tf != cp->tf)
-      panic("trap ret wrong tf");
-    if(cpus[cpu()].nlock){
-      cprintf("num=%d\n", num);
-      panic("syscall returning locks held");
-    }
-    if((read_eflags() & FL_IF) == 0)
-      panic("syscall returning but FL_IF clear");
-    if(read_esp() < (uint)cp->kstack ||
-       read_esp() >= (uint)cp->kstack + KSTACKSIZE)
-      panic("trap ret esp wrong");
     if(cp->killed)
       proc_exit();
-    // XXX probably ought to lgdt on trap return
     return;
   }
 
-  //if(read_eflags() & FL_IF)
-  //panic("interrupt but interrupts enabled");
-
   if(v == (IRQ_OFFSET + IRQ_TIMER)){
     struct proc *cp = curproc[cpu()];
     lapic_timerintr();
@@ -108,18 +68,13 @@ trap(struct trapframe *tf)
 
   if(v == (IRQ_OFFSET + IRQ_IDE)){
     ide_intr();
-    if(cpus[cpu()].nlock)
-      panic("ide_intr returned while holding a lock");
     cli(); // prevent a waiting interrupt from overflowing stack
     lapic_eoi();
     return;
   }
 
   if(v == (IRQ_OFFSET + IRQ_KBD)){
     kbd_intr();
-    if(cpus[cpu()].nlock){
-      panic("kbd_intr returned while holding a lock");
-    }
     cli(); // prevent a waiting interrupt from overflowing stack
     lapic_eoi();
     return;