cvs commit: src/sys/sys proc.h src/sys/kern kern_thread.c

[Jeff Roberson]

jeff        2007-06-12 07:24:47 UTC

  FreeBSD src repository

  Modified files:
    sys/sys              proc.h 
    sys/kern             kern_thread.c 
  Log:
  Solve a complex exit race introduced with thread_lock:
   - Add a count of exiting threads, p_exitthreads, to struct proc.
   - Increment p_exithreads when we set the deadthread in thread_exit().
   - When we thread_stash() a deadthread use an atomic to drop the count.
   - Spin until the p_exithreads count reaches 0 in thread_wait().
   - Lock the last exiting thread momentarily to be certain that it has
     exited cpu_throw().
   - Restructure thread_wait().  It does not need a loop as there will only
     ever be one thread.
  
  Tested by:      moose at opera.com
  Reported by:    kris, moose at opera.com
  
  Revision  Changes    Path
  1.249     +33 -15    src/sys/kern/kern_thread.c
  1.484     +1 -0      src/sys/sys/proc.h