do exec cleanup (after successful exec) in a wq task.

a2bd6f68 · Nickolai Zeldovich · 32692beb · a2bd6f68 · a2bd6f68
--- a/include/proc.hh
+++ b/include/proc.hh
@@ -86,6 +86,7 @@ struct proc : public rcu_freed {
  LIST_ENTRY(proc) cv_sleep;   // Linked list of processes sleeping on a cv
  u64 user_fs_;
  u64 unmap_tlbreq_;
+  int exec_cpuid_;

  static proc* alloc();
  void         set_state(procstate_t s);

--- a/kernel/exec.cc
+++ b/kernel/exec.cc
@@ -173,17 +173,29 @@ bad:
  cilk_abort(-1);
 }

+static void
+exec_cleanup(vmap *oldvmap, uwq *olduwq)
+{
+  if (olduwq != nullptr)
+    olduwq->dec();
+  oldvmap->decref();
+}
+
 int
 exec(const char *path, char **argv)
 {
  struct inode *ip = nullptr;
  struct vmap *vmp = nullptr;
-  uwq* uwq = nullptr;
+  uwq* newuwq = nullptr;
  struct elfhdr elf;
  struct proghdr ph;
  u64 off;
  int i;
-  struct vmap *oldvmap;
+  vmap* oldvmap;
+  uwq* olduwq;
+  cwork* w;
+
+  myproc()->exec_cpuid_ = mycpuid();
  
  if((ip = namei(myproc()->cwd, path)) == 0)
    return -1;
@@ -204,7 +216,7 @@ exec(const char *path, char **argv)
  if((vmp = vmap::alloc()) == 0)
    goto bad;

-  if((uwq = uwq::alloc(vmp, myproc()->ftable)) == 0)
+  if((newuwq = uwq::alloc(vmp, myproc()->ftable)) == 0)
    goto bad;

  // Arguments for work queue
@@ -223,7 +235,7 @@ exec(const char *path, char **argv)
             sizeof(type)) != sizeof(type))
      goto bad;
    if (type == ELF_PROG_NOTE) {
-      if (donotes(ip, uwq, off) < 0) {
+      if (donotes(ip, newuwq, off) < 0) {
        cilk_abort(-1);
        break;
      }
@@ -243,14 +255,19 @@ exec(const char *path, char **argv)

  // Commit to the user image.
  oldvmap = myproc()->vmap;
+  olduwq = myproc()->uwq;
  myproc()->vmap = vmp;
-  if (myproc()->uwq != nullptr)
-    myproc()->uwq->dec();
-  myproc()->uwq = uwq;
+  myproc()->uwq = newuwq;
  myproc()->tf->rip = elf.entry;
  
  switchvm(myproc());
-  oldvmap->decref();
+
+  w = new cwork();
+  assert(w);
+  w->rip = (void*) exec_cleanup;
+  w->arg0 = oldvmap;
+  w->arg1 = olduwq;
+  assert(wq_pushto(w, myproc()->exec_cpuid_) >= 0);

  gc_end_epoch();
  return 0;
@@ -259,8 +276,8 @@ exec(const char *path, char **argv)
  cprintf("exec failed\n");
  if(vmp)
    vmp->decref();
-  if(uwq)
-    uwq->dec();
+  if(newuwq)
+    newuwq->dec();
  gc_end_epoch();
  return 0;
 }