signals: eventpoll: do not use sigprocmask()

sigprocmask() should die. None of the current callers actually
need this strange interface.

Change fs/eventpoll.c to use set_current_blocked(). This also
means we should not worry about SIGKILL/SIGSTOP.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: Eric Wong <normalperson@yhbt.net>
Cc: Jason Baron <jbaron@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

fs/eventpoll.c

@@ -1975,8 +1975,8 @@ SYSCALL_DEFINE6(epoll_pwait, int, epfd, struct epoll_event __user *, events,
 			return -EINVAL;
 		if (copy_from_user(&ksigmask, sigmask, sizeof(ksigmask)))
 			return -EFAULT;
-		sigdelsetmask(&ksigmask, sigmask(SIGKILL) | sigmask(SIGSTOP));
-		sigprocmask(SIG_SETMASK, &ksigmask, &sigsaved);
+		sigsaved = current->blocked;
+		set_current_blocked(&ksigmask);
 	}
 
 	error = sys_epoll_wait(epfd, events, maxevents, timeout);
@@ -1993,7 +1993,7 @@ SYSCALL_DEFINE6(epoll_pwait, int, epfd, struct epoll_event __user *, events,
 			       sizeof(sigsaved));
 			set_restore_sigmask();
 		} else
-			sigprocmask(SIG_SETMASK, &sigsaved, NULL);
+			set_current_blocked(&sigsaved);
 	}
 
 	return error;
@@ -2020,8 +2020,8 @@ COMPAT_SYSCALL_DEFINE6(epoll_pwait, int, epfd,
 		if (copy_from_user(&csigmask, sigmask, sizeof(csigmask)))
 			return -EFAULT;
 		sigset_from_compat(&ksigmask, &csigmask);
-		sigdelsetmask(&ksigmask, sigmask(SIGKILL) | sigmask(SIGSTOP));
-		sigprocmask(SIG_SETMASK, &ksigmask, &sigsaved);
+		sigsaved = current->blocked;
+		set_current_blocked(&ksigmask);
 	}
 
 	err = sys_epoll_wait(epfd, events, maxevents, timeout);
@@ -2038,7 +2038,7 @@ COMPAT_SYSCALL_DEFINE6(epoll_pwait, int, epfd,
 			       sizeof(sigsaved));
 			set_restore_sigmask();
 		} else
-			sigprocmask(SIG_SETMASK, &sigsaved, NULL);
+			set_current_blocked(&sigsaved);
 	}
 
 	return err;