On 8/9/22 7:06 AM, Kumar Kartikeya Dwivedi wrote:
Add a regression test to check against invalid check_and_init_map_value
call inside prealloc_lru_pop.
To actually observe a kind of problem this can cause, set debug to 1
when running the test locally without the fix. Then, just observe the
refcount which keeps increasing on each run of the test. With timers or
spin locks, it would cause unpredictable results when racing.
...
bash-5.1# ./test_progs -t lru_bug
test_progs-192 [000] d..21 354.838821: bpf_trace_printk: ref: 4
test_progs-192 [000] d..21 354.842824: bpf_trace_printk: ref: 5
bash-5.1# ./test_progs -t lru_bug
test_progs-193 [000] d..21 356.722813: bpf_trace_printk: ref: 5
test_progs-193 [000] d..21 356.727071: bpf_trace_printk: ref: 6
... and so on.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@xxxxxxxxx>
Ack with a minor nit below.
Acked-by: Yonghong Song <yhs@xxxxxx>
---
.../selftests/bpf/prog_tests/lru_bug.c | 19 ++++++
tools/testing/selftests/bpf/progs/lru_bug.c | 67 +++++++++++++++++++
2 files changed, 86 insertions(+)
create mode 100644 tools/testing/selftests/bpf/prog_tests/lru_bug.c
create mode 100644 tools/testing/selftests/bpf/progs/lru_bug.c
diff --git a/tools/testing/selftests/bpf/prog_tests/lru_bug.c b/tools/testing/selftests/bpf/prog_tests/lru_bug.c
new file mode 100644
index 000000000000..3bcb5bc62d5a
--- /dev/null
+++ b/tools/testing/selftests/bpf/prog_tests/lru_bug.c
@@ -0,0 +1,19 @@
+// SPDX-License-Identifier: GPL-2.0
+#include <test_progs.h>
+
+#include "lru_bug.skel.h"
+
+void serial_test_lru_bug(void)
+{
+ struct lru_bug *skel;
+ int ret;
+
+ skel = lru_bug__open_and_load();
+ if (!ASSERT_OK_PTR(skel, "lru_bug__open_and_load"))
+ return;
+ ret = lru_bug__attach(skel);
+ if (!ASSERT_OK(ret, "lru_bug__attach"))
+ return;
If not ASSERT_OK, should go to lru_bug__destroy(skel).
+ usleep(1);
+ ASSERT_OK(skel->data->result, "prealloc_lru_pop doesn't call check_and_init_map_value");
Missing
lru_bug__destroy(skel);
.
+}
[...]
