1. 10 Jun, 2008 1 commit
    • Oleg Nesterov's avatar
      sched: fix TASK_WAKEKILL vs SIGKILL race · 16882c1e
      Oleg Nesterov authored
      schedule() has the special "TASK_INTERRUPTIBLE && signal_pending()" case,
      this allows us to do
      
      	current->state = TASK_INTERRUPTIBLE;
      	schedule();
      
      without fear to sleep with pending signal.
      
      However, the code like
      
      	current->state = TASK_KILLABLE;
      	schedule();
      
      is not right, schedule() doesn't take TASK_WAKEKILL into account. This means
      that mutex_lock_killable(), wait_for_completion_killable(), down_killable(),
      schedule_timeout_killable() can miss SIGKILL (and btw the second SIGKILL has
      no effect).
      
      Introduce the new helper, signal_pending_state(), and change schedule() to
      use it. Hopefully it will have more users, that is why the task's state is
      passed separately.
      
      Note this "__TASK_STOPPED | __TASK_TRACED" check in signal_pending_state().
      This is needed to preserve the current behaviour (ptrace_notify). I hope
      this check will be removed soon, but this (afaics good) change needs the
      separate discussion.
      
      The fast path is "(state & (INTERRUPTIBLE | WAKEKILL)) + signal_pending(p)",
      basically the same that schedule() does now. However, this patch of course
      bloats schedule().
      Signed-off-by: default avatarOleg Nesterov <oleg@tv-sign.ru>
      Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      16882c1e
  2. 05 Jun, 2008 39 commits