io_uring: Fix io_cqring_wait() not restoring sigmask on get_timespec64() failure

This bug was introduced in commit 950e79dd ("io_uring: minor
io_cqring_wait() optimization"), which was made in preparation for
adc8682e ("io_uring: Add support for napi_busy_poll"). The latter
got reverted in cb318216 ("Revert "io_uring: Add support for
napi_busy_poll""), so simply undo the former as well.

Cc: stable@vger.kernel.org
Fixes: 950e79dd ("io_uring: minor io_cqring_wait() optimization")
Signed-off-by: Alexey Izbyshev <izbyshev@ispras.ru>
Link: https://lore.kernel.org/r/20240405125551.237142-1-izbyshev@ispras.ruSigned-off-by: Jens Axboe <axboe@kernel.dk>

io_uring/io_uring.c

@@ -2602,19 +2602,6 @@ static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events,
 	if (__io_cqring_events_user(ctx) >= min_events)
 		return 0;
 
-	if (sig) {
-#ifdef CONFIG_COMPAT
-		if (in_compat_syscall())
-			ret = set_compat_user_sigmask((const compat_sigset_t __user *)sig,
-						      sigsz);
-		else
-#endif
-			ret = set_user_sigmask(sig, sigsz);
-
-		if (ret)
-			return ret;
-	}
-
 	init_waitqueue_func_entry(&iowq.wq, io_wake_function);
 	iowq.wq.private = current;
 	INIT_LIST_HEAD(&iowq.wq.entry);
@@ -2633,6 +2620,19 @@ static int io_cqring_wait(struct io_ring_ctx *ctx, int min_events,
 		io_napi_adjust_timeout(ctx, &iowq, &ts);
 	}
 
+	if (sig) {
+#ifdef CONFIG_COMPAT
+		if (in_compat_syscall())
+			ret = set_compat_user_sigmask((const compat_sigset_t __user *)sig,
+						      sigsz);
+		else
+#endif
+			ret = set_user_sigmask(sig, sigsz);
+
+		if (ret)
+			return ret;
+	}
+
 	io_napi_busy_loop(ctx, &iowq);
 
 	trace_io_uring_cqring_wait(ctx, min_events);