xtensa: use set_current_blocked() and block_sigmask()

As described in commit e6fa16ab9c1e ("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 5e6292c0f28f
("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: Chris Zankel <chris@zankel.net>
Signed-off-by: Matt Fleming <matt.fleming@intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/xtensa/kernel/signal.c

@@ -260,10 +260,7 @@ asmlinkage long xtensa_rt_sigreturn(long a0, long a1, long a2, long a3,
 		goto badframe;
 
 	sigdelsetmask(&set, ~_BLOCKABLE);
-	spin_lock_irq(&current->sighand->siglock);
-	current->blocked = set;
-	recalc_sigpending();
-	spin_unlock_irq(&current->sighand->siglock);
+	set_current_blocked(&set);
 
 	if (restore_sigcontext(regs, frame))
 		goto badframe;
@@ -448,11 +445,8 @@ asmlinkage long xtensa_rt_sigsuspend(sigset_t __user *unewset,
 		return -EFAULT;
 
 	sigdelsetmask(&newset, ~_BLOCKABLE);
-	spin_lock_irq(&current->sighand->siglock);
 	saveset = current->blocked;
-	current->blocked = newset;
-	recalc_sigpending();
-	spin_unlock_irq(&current->sighand->siglock);
+	set_current_blocked(&newset);
 
 	regs->areg[2] = -EINTR;
 	while (1) {
@@ -539,12 +533,7 @@ int do_signal(struct pt_regs *regs, sigset_t *oldset)
 		if (ret)
 			return ret;
 
-		spin_lock_irq(&current->sighand->siglock);
-		sigorsets(&current->blocked, &current->blocked, &ka.sa.sa_mask);
-		if (!(ka.sa.sa_flags & SA_NODEFER))
-			sigaddset(&current->blocked, signr);
-		recalc_sigpending();
-		spin_unlock_irq(&current->sighand->siglock);
+		block_sigmask(&ka, signr);
 		if (current->ptrace & PT_SINGLESTEP)
 			task_pt_regs(current)->icountlevel = 1;