binder: use EINTR for interrupted wait for work

when interrupted by a signal, binder_wait_for_work currently returns
-ERESTARTSYS. This error code isn't propagated to user space, but a way
to handle interruption due to signals must be provided to code using
this API.

Replace this instance of -ERESTARTSYS with -EINTR, which is propagated
to user space.

binder_wait_for_work
Signed-off-by: NMarco Ballesio <balejs@google.com>
Signed-off-by: NLi Li <dualli@google.com>
Test: built, booted, interrupted a worker thread within
Acked-by: NTodd Kjos <tkjos@google.com>
Link: https://lore.kernel.org/r/20210316011630.1121213-3-dualli@chromium.orgSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/android/binder.c

@@ -3710,7 +3710,7 @@ static int binder_wait_for_work(struct binder_thread *thread,
 		binder_inner_proc_lock(proc);
 		list_del_init(&thread->waiting_thread_node);
 		if (signal_pending(current)) {
-			ret = -ERESTARTSYS;
+			ret = -EINTR;
 			break;
 		}
 	}
@@ -4853,7 +4853,7 @@ static long binder_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
 	if (thread)
 		thread->looper_need_return = false;
 	wait_event_interruptible(binder_user_error_wait, binder_stop_on_user_error < 2);
-	if (ret && ret != -ERESTARTSYS)
+	if (ret && ret != -EINTR)
 		pr_info("%d:%d ioctl %x %lx returned %d\n", proc->pid, current->pid, cmd, arg, ret);
 err_unlocked:
 	trace_binder_ioctl_done(ret);