signals: sys_ssetmask/sys_rt_sigsuspend should use set_current_blocked()

sys_ssetmask(), sys_rt_sigsuspend() and compat_sys_rt_sigsuspend()
change ->blocked directly.  This is not correct, see the changelog in
e6fa16ab "signal: sigprocmask() should do retarget_shared_pending()"

Change them to use set_current_blocked().

Another change is that now we are doing ->saved_sigmask = ->blocked
lockless, it doesn't make any sense to do this under ->siglock.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Reviewed-by: Matt Fleming <matt.fleming@linux.intel.com>
Acked-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/kernel/compat.c b/kernel/compat.c
index 18197ae..616c781 100644
--- a/kernel/compat.c
+++ b/kernel/compat.c
@@ -992,11 +992,8 @@
 	sigset_from_compat(&newset, &newset32);
 	sigdelsetmask(&newset, sigmask(SIGKILL)|sigmask(SIGSTOP));
 
-	spin_lock_irq(&current->sighand->siglock);
 	current->saved_sigmask = current->blocked;
-	current->blocked = newset;
-	recalc_sigpending();
-	spin_unlock_irq(&current->sighand->siglock);
+	set_current_blocked(&newset);
 
 	current->state = TASK_INTERRUPTIBLE;
 	schedule();