This makes more sense.
But could you explain in a litter more detail?
What data structures are protected? Task struture or something else?

Thank you very much.
Yuxin


On Mon, Jul 21, 2014 at 5:34 AM, Adam Lackorzynski <adam@os.inf.tu-dresden.de> wrote:
On Fri Jul 18, 2014 at 18:34:31 -0400, Yuxin Ren wrote:
> I note that when a thread does memory or capability mapping, both over
> system call and IPC, it needs take a lock, which is the existence_lock of
> target task. I cannot understand it needs take a per task, as cap/page
> table are per thread.
> What data does this lock to protect?

Memory as well as caps are per task, so the lock makes sure that the
task does not disappear while an operation is in progress.


Adam
--
Adam                 adam@os.inf.tu-dresden.de
  Lackorzynski         http://os.inf.tu-dresden.de/~adam/

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