On Tue, 2008-06-10 at 16:13 -0400, Jeff Layton wrote:
> We can't call nfs_callback_down() until after nfs_callback_up()
> returns, so we're guaranteed to have "task" set to a valid task
> (presuming that nfs_callback_up() doesn't return error). We also can't
> return from nfs_callback_down() until after the nfs_callback_svc() has
> exited. kthread_stop() will block until it does.
The code I'm alluding to is in kthread():
/* OK, tell user we're spawned, wait for stop or wakeup */
__set_current_state(TASK_UNINTERRUPTIBLE);
complete(&create->started);
schedule();
if (!kthread_should_stop())
ret = threadfn(data);
schedule() is called _after_ the complete() call, and _before_ we
execute threadfn() a.k.a. nfs_callback_svc(). If nfs_alloc_client() has
time to call nfs_callback_down() before the above thread gets scheduled
back in, then threadfn() doesn't get called at all, since
kthread_should_stop() is true.
Cheers
Trond
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