[PATCH RFC bpf-next 8/9] selftests/hid: add test for hid_bpf_schedule_delayed_work

[Benjamin Tissoires <bentiss@kernel.org>]

This test checks that we can actually execute in a sleepable context
the job called by hid_bpf_offload().

When an event is injected, we push it on a map of type queue and schedule
a work.
When that work kicks in, it pulls the event from the queue, and wakes
up userspace through a ring buffer.

The use of the ring buffer is there to not have sleeps in userspace
because we have no guarantees of the timing of when those jobs will be
called.

Signed-off-by: Benjamin Tissoires <bentiss@kernel.org>
---
 tools/testing/selftests/hid/hid_bpf.c              | 57 ++++++++++++++++++++++
 tools/testing/selftests/hid/progs/hid.c            | 55 +++++++++++++++++++++
 .../testing/selftests/hid/progs/hid_bpf_helpers.h  |  2 +
 3 files changed, 114 insertions(+)

diff --git a/tools/testing/selftests/hid/hid_bpf.c b/tools/testing/selftests/hid/hid_bpf.c
index 9ff02c737144..bb95ff90951b 100644
--- a/tools/testing/selftests/hid/hid_bpf.c
+++ b/tools/testing/selftests/hid/hid_bpf.c
@@ -875,6 +875,63 @@ TEST_F(hid_bpf, test_hid_user_raw_request_call)
 	ASSERT_EQ(args.data[1], 2);
 }
 
+static __u8 workload_data;
+
+static int handle_event(void *ctx, void *data, size_t data_sz)
+{
+	const __u8 *e = data;
+
+	workload_data = *e;
+
+	return 0;
+}
+
+/*
+ * Call hid_bpf_schedule_delayed_work against the given uhid device,
+ * check that the program is called and does the expected.
+ */
+TEST_F(hid_bpf, test_hid_schedule_work)
+{
+	const struct test_program progs[] = {
+		{ .name = "hid_defer_event" },
+		{ .name = "hid_offload_notify" },
+	};
+	struct ring_buffer *rb = NULL;
+	__u8 buf[10] = {0};
+	__u32* delay;
+	int err;
+
+	LOAD_PROGRAMS(progs);
+
+	/* Set up ring buffer polling */
+	rb = ring_buffer__new(bpf_map__fd(self->skel->maps.rb), handle_event, NULL, NULL);
+	ASSERT_OK_PTR(rb) TH_LOG("Failed to create ring buffer");
+	ASSERT_EQ(workload_data, 0);
+
+	delay = (__u32 *)&buf[2];
+
+	/* inject one event */
+	buf[0] = 1;
+	buf[1] = 42; /* this will be placed in the ring buffer */
+	*delay = 0;
+	uhid_send_event(_metadata, self->uhid_fd, buf, 6);
+
+	err = ring_buffer__poll(rb, 100 /* timeout, ms */);
+	ASSERT_EQ(err, 1) TH_LOG("error while calling ring_buffer__poll");
+
+	ASSERT_EQ(workload_data, 42);
+
+	/* inject one another */
+	buf[0] = 1;
+	buf[1] = 53; /* this will be placed in the ring buffer */
+	*delay = 100;
+	uhid_send_event(_metadata, self->uhid_fd, buf, 6);
+
+	err = ring_buffer__poll(rb, 1000 /* timeout, ms */);
+	ASSERT_EQ(err, 1) TH_LOG("error while calling ring_buffer__poll");
+	ASSERT_EQ(workload_data, 53);
+}
+
 /*
  * Attach hid_insert{0,1,2} to the given uhid device,
  * retrieve and open the matching hidraw node,
diff --git a/tools/testing/selftests/hid/progs/hid.c b/tools/testing/selftests/hid/progs/hid.c
index f67d35def142..95a03fb0494a 100644
--- a/tools/testing/selftests/hid/progs/hid.c
+++ b/tools/testing/selftests/hid/progs/hid.c
@@ -250,3 +250,58 @@ int BPF_PROG(hid_test_insert3, struct hid_bpf_ctx *hid_ctx)
 
 	return 0;
 }
+
+struct test_report {
+	__u8 data[6];
+};
+
+struct {
+	__uint(type, BPF_MAP_TYPE_QUEUE);
+	__uint(max_entries, 8);
+	__type(value, struct test_report);
+} queue SEC(".maps");
+
+struct {
+    __uint(type, BPF_MAP_TYPE_RINGBUF);
+    __uint(max_entries, 8);
+} rb SEC(".maps");
+
+SEC("?fmod_ret.s/hid_bpf_offload")
+int BPF_PROG(hid_offload_notify, struct hid_bpf_ctx *hid_ctx)
+{
+	struct test_report buf;
+	__u8 *rb_elem;
+
+	if (bpf_map_pop_elem(&queue, &buf))
+		return 0;
+
+	rb_elem = bpf_ringbuf_reserve(&rb, sizeof(*rb_elem), 0);
+	if (!rb_elem)
+		return 0;
+
+	*rb_elem = buf.data[1];
+
+	bpf_ringbuf_submit(rb_elem, 0);
+
+	return 0;
+}
+
+SEC("?fmod_ret/hid_bpf_device_event")
+int BPF_PROG(hid_defer_event, struct hid_bpf_ctx *hctx)
+{
+	__u8 *data = hid_bpf_get_data(hctx, 0 /* offset */, 6 /* size */);
+	struct test_report buf;
+	__u32 delay;
+
+	if (!data)
+		return 0; /* EPERM check */
+
+	__builtin_memcpy(&buf.data, data, 6);
+
+	delay = *(__u32 *)&data[2];
+
+	bpf_map_push_elem(&queue, &buf, BPF_ANY);
+	hid_bpf_schedule_delayed_work(hctx, delay);
+
+	return -1; /* discard the event */
+}
diff --git a/tools/testing/selftests/hid/progs/hid_bpf_helpers.h b/tools/testing/selftests/hid/progs/hid_bpf_helpers.h
index 9cd56821d0f1..a844c7e89766 100644
--- a/tools/testing/selftests/hid/progs/hid_bpf_helpers.h
+++ b/tools/testing/selftests/hid/progs/hid_bpf_helpers.h
@@ -100,5 +100,7 @@ extern int hid_bpf_input_report(struct hid_bpf_ctx *ctx,
 				enum hid_report_type type,
 				__u8 *data,
 				size_t buf__sz) __ksym;
+extern bool hid_bpf_schedule_delayed_work(struct hid_bpf_ctx *ctx,
+					  unsigned int delay_ms) __ksym;
 
 #endif /* __HID_BPF_HELPERS_H */

-- 
2.43.0