scoped_acquire

fed708d4 · Nickolai Zeldovich · 006c474e · fed708d4 · fed708d4
--- a/cpputil.hh
+++ b/cpputil.hh
@@ -34,6 +34,15 @@ mkpair(const A &a, const B &b)
  return pair<A, B>(a, b);
 }

+class scoped_acquire {
+ private:
+  spinlock *_l;
+
+ public:
+  scoped_acquire(spinlock *l) : _l(l) { acquire(_l); }
+  ~scoped_acquire() { release(_l); }
+};
+
 /* C++ runtime */
 void *operator new(unsigned long nbytes);
 void *operator new(unsigned long nbytes, void *buf);

--- a/vm.cc
+++ b/vm.cc
@@ -15,6 +15,7 @@ extern "C" {
 #include "vm.hh"
 #include "gc.hh"
 #include "crange.hh"
+#include "cpputil.hh"

 enum { vm_debug = 0 };

@@ -356,27 +357,23 @@ vmap::lookup(uptr start, uptr len)
 int
 vmap::insert(vmnode *n, uptr va_start)
 {
-  acquire(&lock);
+  scoped_acquire sa(&lock);
  u64 len = n->npages * PGSIZE;

  if (lookup(va_start, len)) {
    cprintf("vmap_insert: overlap\n");
-    release(&lock);
    return -1;
  }

  vma *e = new vma();
-  if (e == 0) {
-    release(&lock);
+  if (e == 0)
    return -1;
-  }

  e->va_start = va_start;
  e->va_end = va_start + len;
  e->n = n;
  n->ref++;
  cr.add(e->va_start, len, (void *) e);
-  release(&lock);
  return 0;
 }

@@ -387,7 +384,7 @@ vmap_copy(struct vmap *m, int share)
  if(nm == 0)
    return 0;

-  acquire(&m->lock);
+  scoped_acquire sa(&m->lock);
  for (range *r: m->cr) {
    struct vma *e = (struct vma *) r->value;
    struct vma *ne = new vma();
@@ -418,12 +415,10 @@ vmap_copy(struct vmap *m, int share)
  if (share)
    lcr3(v2p(m->pml4));  // Reload hardware page table

-  release(&m->lock);
  return nm;

 err:
  delete nm;
-  release(&m->lock);
  return 0;
 }