fix up growproc() to use crange correctly

no need for vmap::lock anymore either

fix up growproc() to use crange correctly
cbc50063 · Nickolai Zeldovich · e6b2a3df · cbc50063 · cbc50063 · cbc50063
--- a/include/crange.hh
+++ b/include/crange.hh
@@ -135,7 +135,6 @@ struct crange {
  range *const crange_head;    // a crange skip list starts with a sentinel range (key 0, sz 0)

  static void mark(range *f, range *s);
-  static void freen(struct range *f, struct range *l);
  static int lock_range(u64 k, u64 sz, int l, range **er, range **pr, range **fr, range **lr, range **sr);

  void print(int);
@@ -193,6 +192,7 @@ struct crange_locked {
  range_iterator begin() const { return range_iterator(prev_->next[0].ptr()); };
  range_iterator end() const { return range_iterator(succ_); };
  void replace(range *r);
+  void replace(range *prev, range *repl);
 };

 static inline range_iterator

--- a/include/vm.hh
+++ b/include/vm.hh
@@ -48,12 +48,10 @@ struct vma : public range {
 // The elements of e[] are not ordered by address.
 struct vmap {
  struct crange cr;
-  struct spinlock lock;        // serialize map/lookup/unmap
  atomic<u64> ref;
  u64 alloc;
  pgmap *const pml4;           // Page table
  char *const kshared;
-  char lockname[16];

  vmap();
  ~vmap();

--- a/kernel/crange.cc
+++ b/kernel/crange.cc
@@ -479,8 +479,11 @@ crange_locked::~crange_locked()
 }

 void
-crange_locked::replace(range *repl)
+crange_locked::replace(range *prev, range *repl)
 {
+  if (!prev)
+    prev = prev_;
+
  range *newlast = 0;
  for (range *e = repl; e; e = e->next[0].ptr()) {
    assert(e->key >= base_ && e->key + e->size <= base_ + size_);
@@ -493,8 +496,8 @@ crange_locked::replace(range *repl)

  // do compare-exchange first, and only then mark the old ranges as deleted;
  // otherwise, concurrent readers may not find either old or new ranges.
-  range *replaced = prev_->next[0].ptr();
-  prev_->next[0] = repl ?: succ_;
+  range *replaced = prev->next[0].ptr();
+  prev->next[0] = repl ?: succ_;
  crange::mark(replaced, succ_);

  for (range *e = replaced; e && e != succ_; e = e->next[0].ptr()) {
@@ -502,3 +505,9 @@ crange_locked::replace(range *repl)
    e->dec_ref();
  }
 }
+
+void
+crange_locked::replace(range *repl)
+{
+  replace(0, repl);
+}
--- a/kernel/proc.cc
+++ b/kernel/proc.cc
@@ -408,74 +408,58 @@ int
 growproc(int n)
 {
  struct vmap *m = myproc()->vmap;
+  auto curbrk = myproc()->brk;

-  if(n < 0 && 0 - n <= myproc()->brk){
+  if(n < 0 && 0 - n <= curbrk){
    myproc()->brk += n;
    return 0;
  }

-  if(n < 0 || n > USERTOP || myproc()->brk + n > USERTOP)
+  if(n < 0 || n > USERTOP || curbrk + n > USERTOP)
    return -1;

-  acquire(&m->lock);
-
-  // find first unallocated address in brk..brk+n
-  uptr newstart = myproc()->brk;
-  u64 newn = n;
-  gc_begin_epoch();
-  while(newn > 0){
-    vma *e = m->lookup(newstart, 1);
-    if(e == 0)
-      break;
-    if(e->vma_end >= newstart + newn){
-      newstart += newn;
-      newn = 0;
-      break;
-    }
-    newn -= e->vma_end - newstart;
-    newstart = e->vma_end;
-  }
-  gc_end_epoch();
-
-  if(newn <= 0){
-    // no need to allocate
-    myproc()->brk += n;
-    release(&m->lock);
-    switchuvm(myproc());
-    return 0;
-  }
-
-  // is there space for newstart..newstart+newn?
-  if(m->lookup(newstart, newn) != 0){
-    cprintf("growproc: not enough room in address space; brk %lx n %d\n",
-            myproc()->brk, n);
-    return -1;
-  }
+  // look one page ahead, to check if the newly allocated region would
+  // abut the next-higher vma? we can't allow that, since then a future
+  // sbrk() would start to use the next region (e.g. the stack).
+  uptr newstart = PGROUNDUP(curbrk);
+  s64 newn = PGROUNDUP(n + curbrk - newstart);
+  range *prev = 0;
+  auto span = m->cr.search_lock(newstart, newstart + newn + PGSIZE);
+  for (range *r: span) {
+    vma *e = (vma*) r;
+
+    if (e->vma_start <= newstart) {
+      if (e->vma_end >= newstart + newn) {
+        myproc()->brk += n;
+        switchuvm(myproc());
+        return 0;
+      }

-  // would the newly allocated region abut the next-higher
-  // vma? we can't allow that, since then a future sbrk()
-  // would start to use the next region (e.g. the stack).
-  if(m->lookup(PGROUNDUP(newstart+newn), 1) != 0){
-    cprintf("growproc: would abut next vma; brk %lx n %d\n",
-            myproc()->brk, n);
-    return -1;
+      newn -= e->vma_end - newstart;
+      newstart = e->vma_end;
+      prev = e;
+    } else {
+      cprintf("growproc: overlap with existing mapping; brk %lx n %d\n",
+              curbrk, n);
+      return -1;
+    }
  }

-  vmnode *vmn = new vmnode(PGROUNDUP(newn) / PGSIZE);
+  vmnode *vmn = new vmnode(newn / PGSIZE);
  if(vmn == 0){
-    release(&m->lock);
    cprintf("growproc: vmn_allocpg failed\n");
    return -1;
  }

-  release(&m->lock); // XXX
-
-  if(m->insert(vmn, newstart) < 0){
+  vma *repl = new vma(m, newstart, newstart+newn, PRIVATE, vmn);
+  if (!repl) {
+    cprintf("growproc: out of vma\n");
    delete vmn;
-    cprintf("growproc: vmap_insert failed\n");
    return -1;
  }

+  span.replace(prev, repl);
+
  myproc()->brk += n;
  switchuvm(myproc());
  return 0;

--- a/kernel/vm.cc
+++ b/kernel/vm.cc
@@ -140,9 +140,6 @@ vma::~vma()
 vmap::vmap()
  : cr(10), pml4(setupkvm()), kshared((char*) ksalloc(slab_kshared))
 {
-  snprintf(lockname, sizeof(lockname), "vmap:%p", this);
-  initlock(&lock, lockname, LOCKSTAT_VM);
-
  ref = 1;
  alloc = 0;

@@ -168,7 +165,6 @@ vmap::vmap()
    ksfree(slab_kshared, kshared);
  if (pml4)
    freevm(pml4);
-  destroylock(&lock);
 }

 vmap::~vmap()
@@ -178,7 +174,6 @@ vmap::~vmap()
  if (pml4)
    freevm(pml4);
  alloc = 0;
-  destroylock(&lock);
 }

 void
@@ -207,9 +202,6 @@ vmap::copy(int share)
  if(nm == 0)
    return 0;

-  scoped_acquire sa(&lock);
-  // XXX how to construct a consistent copy?
-
  for (range *r: cr) {
    vma *e = (vma *) r;