[CRIU] [PATCH 07/21] parasite: allocate stack for each thread

[Cyrill Gorcunov]

On Fri, May 24, 2013 at 04:20:10PM +0400, Andrey Vagin wrote:
> It will be used for executed parasite as a daemon.

I believe more detailed comment will make Pavel more happy. In short
what we have previously -- the stack has been preallocated in parasite
blob itself and bootstrap procedure calculated the value needed for %rsp.

With this patch applied we provide every thread own stack as:

 - find out how many threads are present
 - calculate the summary size of all stacks
 - when we ask dumpee to provide us memory area needed to run
   parasite code, we pass summary size needed for everything
 - when parasite code is asked to run we calculate %rsp needed
   taking into account the thread number (ie offsets) and then
   setup proper %rsp via ptrace call, instead of calculating it
   in bootstrap parasite code

	Cyrill