signal: Add restore_user_sigmask()

Refactor the logic to restore the sigmask before the syscall
returns into an api.
This is useful for versions of syscalls that pass in the
sigmask and expect the current->sigmask to be changed during
the execution and restored after the execution of the syscall.

With the advent of new y2038 syscalls in the subsequent patches,
we add two more new versions of the syscalls (for pselect, ppoll
and io_pgetevents) in addition to the existing native and compat
versions. Adding such an api reduces the logic that would need to
be replicated otherwise.

Signed-off-by: Deepa Dinamani <deepa.kernel@gmail.com>
Signed-off-by: Arnd Bergmann <arnd@arndb.de>

3 files changed, 16 insertions, 103 deletions

diff --git a/fs/aio.c b/fs/aio.c
index 6ddb63ee8eb6..39a1f2df6805 100644
--- a/fs/aio.c
+++ b/fs/aio.c
@@ -2110,18 +2110,9 @@ SYSCALL_DEFINE6(io_pgetevents,
 		return ret;
 
 	ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &ts : NULL);
-	if (signal_pending(current)) {
-		if (ksig.sigmask) {
-			current->saved_sigmask = sigsaved;
-			set_restore_sigmask();
-		}
-
-		if (!ret)
-			ret = -ERESTARTNOHAND;
-	} else {
-		if (ksig.sigmask)
-			sigprocmask(SIG_SETMASK, &sigsaved, NULL);
-	}
+	restore_user_sigmask(ksig.sigmask, &sigsaved);
+	if (signal_pending(current) && !ret)
+		ret = -ERESTARTNOHAND;
 
 	return ret;
 }
@@ -2175,17 +2166,9 @@ COMPAT_SYSCALL_DEFINE6(io_pgetevents,
 		return ret;
 
 	ret = do_io_getevents(ctx_id, min_nr, nr, events, timeout ? &t : NULL);
-	if (signal_pending(current)) {
-		if (ksig.sigmask) {
-			current->saved_sigmask = sigsaved;
-			set_restore_sigmask();
-		}
-		if (!ret)
-			ret = -ERESTARTNOHAND;
-	} else {
-		if (ksig.sigmask)
-			sigprocmask(SIG_SETMASK, &sigsaved, NULL);
-	}
+	restore_user_sigmask(ksig.sigmask, &sigsaved);
+	if (signal_pending(current) && !ret)
+		ret = -ERESTARTNOHAND;
 
 	return ret;
 }
diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index 2d86eeba837b..8a5a1010886b 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -2229,20 +2229,7 @@ SYSCALL_DEFINE6(epoll_pwait, int, epfd, struct epoll_event __user *, events,
 
 	error = do_epoll_wait(epfd, events, maxevents, timeout);
 
-	/*
-	 * If we changed the signal mask, we need to restore the original one.
-	 * In case we've got a signal while waiting, we do not restore the
-	 * signal mask yet, and we allow do_signal() to deliver the signal on
-	 * the way back to userspace, before the signal mask is restored.
-	 */
-	if (sigmask) {
-		if (error == -EINTR) {
-			memcpy(&current->saved_sigmask, &sigsaved,
-			       sizeof(sigsaved));
-			set_restore_sigmask();
-		} else
-			set_current_blocked(&sigsaved);
-	}
+	restore_user_sigmask(sigmask, &sigsaved);
 
 	return error;
 }
@@ -2267,20 +2254,7 @@ COMPAT_SYSCALL_DEFINE6(epoll_pwait, int, epfd,
 
 	err = do_epoll_wait(epfd, events, maxevents, timeout);
 
-	/*
-	 * If we changed the signal mask, we need to restore the original one.
-	 * In case we've got a signal while waiting, we do not restore the
-	 * signal mask yet, and we allow do_signal() to deliver the signal on
-	 * the way back to userspace, before the signal mask is restored.
-	 */
-	if (sigmask) {
-		if (err == -EINTR) {
-			memcpy(&current->saved_sigmask, &sigsaved,
-			       sizeof(sigsaved));
-			set_restore_sigmask();
-		} else
-			set_current_blocked(&sigsaved);
-	}
+	restore_user_sigmask(sigmask, &sigsaved);
 
 	return err;
 }
diff --git a/fs/select.c b/fs/select.c
index 65c78b4147a2..eb9132520197 100644
--- a/fs/select.c
+++ b/fs/select.c
@@ -724,19 +724,7 @@ static long do_pselect(int n, fd_set __user *inp, fd_set __user *outp,
 	ret = core_sys_select(n, inp, outp, exp, to);
 	ret = poll_select_copy_remaining(&end_time, tsp, 0, ret);
 
-	if (ret == -ERESTARTNOHAND) {
-		/*
-		 * Don't restore the signal mask yet. Let do_signal() deliver
-		 * the signal on the way back to userspace, before the signal
-		 * mask is restored.
-		 */
-		if (sigmask) {
-			memcpy(&current->saved_sigmask, &sigsaved,
-					sizeof(sigsaved));
-			set_restore_sigmask();
-		}
-	} else if (sigmask)
-		sigprocmask(SIG_SETMASK, &sigsaved, NULL);
+	restore_user_sigmask(sigmask, &sigsaved);
 
 	return ret;
 }
@@ -1060,21 +1048,11 @@ SYSCALL_DEFINE5(ppoll, struct pollfd __user *, ufds, unsigned int, nfds,
 
 	ret = do_sys_poll(ufds, nfds, to);
 
+	restore_user_sigmask(sigmask, &sigsaved);
+
 	/* We can restart this syscall, usually */
-	if (ret == -EINTR) {
-		/*
-		 * Don't restore the signal mask yet. Let do_signal() deliver
-		 * the signal on the way back to userspace, before the signal
-		 * mask is restored.
-		 */
-		if (sigmask) {
-			memcpy(&current->saved_sigmask, &sigsaved,
-					sizeof(sigsaved));
-			set_restore_sigmask();
-		}
+	if (ret == -EINTR)
 		ret = -ERESTARTNOHAND;
-	} else if (sigmask)
-		sigprocmask(SIG_SETMASK, &sigsaved, NULL);
 
 	ret = poll_select_copy_remaining(&end_time, tsp, 0, ret);
 
@@ -1316,19 +1294,7 @@ static long do_compat_pselect(int n, compat_ulong_t __user *inp,
 	ret = compat_core_sys_select(n, inp, outp, exp, to);
 	ret = compat_poll_select_copy_remaining(&end_time, tsp, 0, ret);
 
-	if (ret == -ERESTARTNOHAND) {
-		/*
-		 * Don't restore the signal mask yet. Let do_signal() deliver
-		 * the signal on the way back to userspace, before the signal
-		 * mask is restored.
-		 */
-		if (sigmask) {
-			memcpy(&current->saved_sigmask, &sigsaved,
-					sizeof(sigsaved));
-			set_restore_sigmask();
-		}
-	} else if (sigmask)
-		sigprocmask(SIG_SETMASK, &sigsaved, NULL);
+	restore_user_sigmask(sigmask, &sigsaved);
 
 	return ret;
 }
@@ -1375,21 +1341,11 @@ COMPAT_SYSCALL_DEFINE5(ppoll, struct pollfd __user *, ufds,
 
 	ret = do_sys_poll(ufds, nfds, to);
 
+	restore_user_sigmask(sigmask, &sigsaved);
+
 	/* We can restart this syscall, usually */
-	if (ret == -EINTR) {
-		/*
-		 * Don't restore the signal mask yet. Let do_signal() deliver
-		 * the signal on the way back to userspace, before the signal
-		 * mask is restored.
-		 */
-		if (sigmask) {
-			memcpy(&current->saved_sigmask, &sigsaved,
-				sizeof(sigsaved));
-			set_restore_sigmask();
-		}
+	if (ret == -EINTR)
 		ret = -ERESTARTNOHAND;
-	} else if (sigmask)
-		sigprocmask(SIG_SETMASK, &sigsaved, NULL);
 
 	ret = compat_poll_select_copy_remaining(&end_time, tsp, 0, ret);