m68k: use set_current_blocked() and block_sigmask()

As described in e6fa16a ("signal: sigprocmask() should do
retarget_shared_pending()") the modification of current->blocked is
incorrect as we need to check whether the signal we're about to block is
pending in the shared queue.

Also, use the new helper function introduced in commit 5e6292c
("signal: add block_sigmask() for adding sigmask to current->blocked")
which centralises the code for updating current->blocked after
successfully delivering a signal and reduces the amount of duplicate code
across architectures.  In the past some architectures got this code wrong,
so using this helper function should stop that from happening again.

Acked-by: Oleg Nesterov <oleg@redhat.com>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Acked-by: Greg Ungerer <gerg@uclinux.org>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

arch/m68k/kernel/signal.c

@@ -795,8 +795,7 @@ asmlinkage int do_sigreturn(unsigned long __unused)
 		goto badframe;
 
 	sigdelsetmask(&set, ~_BLOCKABLE);
-	current->blocked = set;
-	recalc_sigpending();
+	set_current_blocked(&set);
 
 	if (restore_sigcontext(regs, &frame->sc, frame + 1))
 		goto badframe;
@@ -821,8 +820,7 @@ asmlinkage int do_rt_sigreturn(unsigned long __unused)
 		goto badframe;
 
 	sigdelsetmask(&set, ~_BLOCKABLE);
-	current->blocked = set;
-	recalc_sigpending();
+	set_current_blocked(&set);
 
 	if (rt_restore_ucontext(regs, sw, &frame->uc))
 		goto badframe;
@@ -1141,10 +1139,7 @@ handle_signal(int sig, struct k_sigaction *ka, siginfo_t *info,
 	if (err)
 		return;
 
-	sigorsets(&current->blocked,&current->blocked,&ka->sa.sa_mask);
-	if (!(ka->sa.sa_flags & SA_NODEFER))
-		sigaddset(&current->blocked,sig);
-	recalc_sigpending();
+	block_sigmask(ka, sig);
 
 	if (test_thread_flag(TIF_DELAYED_TRACE)) {
 		regs->sr &= ~0x8000;