[CRIU] [PATCH 09/10] restore: Add restoration of alternative signal stack, v2

[Cyrill Gorcunov]

On Tue, Jul 09, 2013 at 09:11:38PM +0400, Pavel Emelyanov wrote:
> > on init we save dumpee sas in memory, thus if something go wrong we restore
> 
> Do we have the sas at hands at that time?

Yes. Look how it works now

- pstree-entry allocated (together with place for sas, but no
  real value yet assigned)

- parasite_init called, which forces dumpee to provide back the
  sas value it has

-------------------------------- pie/parasite.c --------------------------------
index 4f6708f..30548c5 100644
@@ -230,6 +230,9 @@ static int init_thread(struct parasite_dump_thread *args)
 	args->tid = tid;
 	args->tls = arch_get_tls();
 
+	ret = sys_sigaltstack(NULL, &args->sas);
+	if (ret)
+		goto err;
 
 	return ret;
 err:
@@ -258,6 +261,10 @@ static int init(struct parasite_init_args *args)
 	if (ret)
 		return -1;
 
+	ret = sys_sigaltstack(NULL, &args->sas);
+	if (ret)
+		goto err;
+

- parasite-syscall.c code encodes these values into protobuf format
  and copies them to pstree entry

- parasite-sysall.c code generates restore sigframe and put these
  values back to rollback if error happened