Bug 18402

the system panics with fatal trap 12 in aio_process when the file is
close(2)'ed and there are outstanding aio requests.

Fix: 

it works fine if close is called after the loop that is doing the aio_error
and aio_return calls, which is where it belongs to begin with.
How-To-Repeat: 
the problem occurred in a program i'm developing and the aio is mixed
in with lots of other stuff.  this code-like sample illustrates what
i'm doing which is causing the problem.  the code is zeroing the disk.
if you need the exact code, let me now

struct aiocb x[100];
int outstanding[100];

open(/dev/rda0)
for(i=0;i<100;i++)
{
  /* setup x[ i ] values */
  aio_write(&x[i]);
  outstanding[i]=1;
}

close(/dev/rda0);       /* bad thing to do here */
while( requests outstanding )
 for(i=0;i<100;i++)
 {
   if( aio_error(&x[i]) == EINPROGRESS )
     continue;

   if( outstanding[i] )
   {
     aio_return(&x[i]);
     outstanding[i]=0;
     /* setup array for aio_suspend */
   }
 }
 aio_suspend();
}
exit();