s390/compat: correct check for EFAULT in rt-signal frame creation

The return code of the __put_user call to store the rt_sigreturn
system call to the user stack if not properly checked, the err
variable is only checked before to the __put_user. Use an if
statement instead.
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>

arch/s390/kernel/compat_signal.c

@@ -412,8 +412,9 @@ static int setup_rt_frame32(int sig, struct k_sigaction *ka, siginfo_t *info,
 		regs->gprs[14] = (__u64 __force) ka->sa.sa_restorer | PSW32_ADDR_AMODE;
 	} else {
 		regs->gprs[14] = (__u64 __force) frame->retcode | PSW32_ADDR_AMODE;
-		err |= __put_user(S390_SYSCALL_OPCODE | __NR_rt_sigreturn,
-				  (u16 __force __user *)(frame->retcode));
+		if (__put_user(S390_SYSCALL_OPCODE | __NR_rt_sigreturn,
+			       (u16 __force __user *)(frame->retcode)))
+			goto give_sigsegv;
 	}
 
 	/* Set up backchain. */