Re: [RFC][PATCH 4/7] Freezer: Fix vfork problem

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On 2/25/07, Rafael J. Wysocki <[email protected]> wrote:
On Sunday, 25 February 2007 11:45, Rafael J. Wysocki wrote:
> Hi,
>
> =========
--- linux-2.6.20-mm2.orig/kernel/power/process.c        2007-02-22 23:44:04.000000000 +0100
+++ linux-2.6.20-mm2/kernel/power/process.c     2007-02-23 22:33:11.000000000 +0100
@@ -127,22 +127,12 @@ static unsigned int try_to_freeze_tasks(
                                cancel_freezing(p);
                                continue;
                        }
-                       if (is_user_space(p)) {
-                               if (!freeze_user_space)
-                                       continue;
-
-                               /* Freeze the task unless there is a vfork
-                                * completion pending
-                                */
-                               if (!p->vfork_done)
-                                       freeze_process(p);
-                       } else {
-                               if (freeze_user_space)
-                                       continue;
+                       if (is_user_space(p) == !freeze_user_space)
+                               continue;


How about ?
if ( ! (is_user_space(p) == freeze_user_space) )
    continue;


BTW one of the concern that vatsa had was; is it ok to allow some of
the tasks to be left running  ( the parent from vfork ) while
freezing.  I guess we can solve this in a nice way.

in fork.c

if (clone_flags & CLONE_VFORK) {
                       p->vfork_done = &vfork;
                       p->flags |= PF_PARENT_WAKEUP_ON_FREEZE;
                       init_completion(&vfork);
}


and in freeze_process(struct task_struct *p)

if ( p->flags & PF_PARENT_WAKEUP_ON_FREEZE ) {
 wake_up_parent();
}

now parent should be wating for these completion via

wait_for_completion_freezable(); // pavel's implementation.

-aneesh
-
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