selftests/bpf: Add tests for kptr_ref refcounting

Check at runtime how various operations for kptr_ref affect its refcount
and verify against the actual count.

Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20220511194654.765705-5-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

diff --git a/tools/testing/selftests/bpf/prog_tests/map_kptr.c b/tools/testing/selftests/bpf/prog_tests/map_kptr.c
index 0081927..8142dd9 100644 (file)
--- a/tools/testing/selftests/bpf/prog_tests/map_kptr.c
+++ b/tools/testing/selftests/bpf/prog_tests/map_kptr.c
@@ -1,5 +1,6 @@
 // SPDX-License-Identifier: GPL-2.0
 #include <test_progs.h>
+#include <network_helpers.h>
 
 #include "map_kptr.skel.h"
 #include "map_kptr_fail.skel.h"
@@ -81,8 +82,13 @@ static void test_map_kptr_fail(void)
        }
 }
 
-static void test_map_kptr_success(void)
+static void test_map_kptr_success(bool test_run)
 {
+       LIBBPF_OPTS(bpf_test_run_opts, opts,
+               .data_in = &pkt_v4,
+               .data_size_in = sizeof(pkt_v4),
+               .repeat = 1,
+       );
        struct map_kptr *skel;
        int key = 0, ret;
        char buf[24];
@@ -91,6 +97,16 @@ static void test_map_kptr_success(void)
        if (!ASSERT_OK_PTR(skel, "map_kptr__open_and_load"))
                return;
 
+       ret = bpf_prog_test_run_opts(bpf_program__fd(skel->progs.test_map_kptr_ref), &opts);
+       ASSERT_OK(ret, "test_map_kptr_ref refcount");
+       ASSERT_OK(opts.retval, "test_map_kptr_ref retval");
+       ret = bpf_prog_test_run_opts(bpf_program__fd(skel->progs.test_map_kptr_ref2), &opts);
+       ASSERT_OK(ret, "test_map_kptr_ref2 refcount");
+       ASSERT_OK(opts.retval, "test_map_kptr_ref2 retval");
+
+       if (test_run)
+               return;
+
        ret = bpf_map_update_elem(bpf_map__fd(skel->maps.array_map), &key, buf, 0);
        ASSERT_OK(ret, "array_map update");
        ret = bpf_map_update_elem(bpf_map__fd(skel->maps.array_map), &key, buf, 0);
@@ -116,7 +132,12 @@ static void test_map_kptr_success(void)
 
 void test_map_kptr(void)
 {
-       if (test__start_subtest("success"))
-               test_map_kptr_success();
+       if (test__start_subtest("success")) {
+               test_map_kptr_success(false);
+               /* Do test_run twice, so that we see refcount going back to 1
+                * after we leave it in map from first iteration.
+                */
+               test_map_kptr_success(true);
+       }
        test_map_kptr_fail();
 }

diff --git a/tools/testing/selftests/bpf/progs/map_kptr.c b/tools/testing/selftests/bpf/progs/map_kptr.c
index 1b0e040..eb82178 100644 (file)
--- a/tools/testing/selftests/bpf/progs/map_kptr.c
+++ b/tools/testing/selftests/bpf/progs/map_kptr.c
@@ -141,7 +141,7 @@ SEC("tc")
 int test_map_kptr(struct __sk_buff *ctx)
 {
        struct map_value *v;
-       int i, key = 0;
+       int key = 0;
 
 #define TEST(map)                                      \
        v = bpf_map_lookup_elem(&map, &key);            \
@@ -162,7 +162,7 @@ SEC("tc")
 int test_map_in_map_kptr(struct __sk_buff *ctx)
 {
        struct map_value *v;
-       int i, key = 0;
+       int key = 0;
        void *map;
 
 #define TEST(map_in_map)                                \
@@ -187,4 +187,106 @@ int test_map_in_map_kptr(struct __sk_buff *ctx)
        return 0;
 }
 
+SEC("tc")
+int test_map_kptr_ref(struct __sk_buff *ctx)
+{
+       struct prog_test_ref_kfunc *p, *p_st;
+       unsigned long arg = 0;
+       struct map_value *v;
+       int key = 0, ret;
+
+       p = bpf_kfunc_call_test_acquire(&arg);
+       if (!p)
+               return 1;
+
+       p_st = p->next;
+       if (p_st->cnt.refs.counter != 2) {
+               ret = 2;
+               goto end;
+       }
+
+       v = bpf_map_lookup_elem(&array_map, &key);
+       if (!v) {
+               ret = 3;
+               goto end;
+       }
+
+       p = bpf_kptr_xchg(&v->ref_ptr, p);
+       if (p) {
+               ret = 4;
+               goto end;
+       }
+       if (p_st->cnt.refs.counter != 2)
+               return 5;
+
+       p = bpf_kfunc_call_test_kptr_get(&v->ref_ptr, 0, 0);
+       if (!p)
+               return 6;
+       if (p_st->cnt.refs.counter != 3) {
+               ret = 7;
+               goto end;
+       }
+       bpf_kfunc_call_test_release(p);
+       if (p_st->cnt.refs.counter != 2)
+               return 8;
+
+       p = bpf_kptr_xchg(&v->ref_ptr, NULL);
+       if (!p)
+               return 9;
+       bpf_kfunc_call_test_release(p);
+       if (p_st->cnt.refs.counter != 1)
+               return 10;
+
+       p = bpf_kfunc_call_test_acquire(&arg);
+       if (!p)
+               return 11;
+       p = bpf_kptr_xchg(&v->ref_ptr, p);
+       if (p) {
+               ret = 12;
+               goto end;
+       }
+       if (p_st->cnt.refs.counter != 2)
+               return 13;
+       /* Leave in map */
+
+       return 0;
+end:
+       bpf_kfunc_call_test_release(p);
+       return ret;
+}
+
+SEC("tc")
+int test_map_kptr_ref2(struct __sk_buff *ctx)
+{
+       struct prog_test_ref_kfunc *p, *p_st;
+       struct map_value *v;
+       int key = 0;
+
+       v = bpf_map_lookup_elem(&array_map, &key);
+       if (!v)
+               return 1;
+
+       p_st = v->ref_ptr;
+       if (!p_st || p_st->cnt.refs.counter != 2)
+               return 2;
+
+       p = bpf_kptr_xchg(&v->ref_ptr, NULL);
+       if (!p)
+               return 3;
+       if (p_st->cnt.refs.counter != 2) {
+               bpf_kfunc_call_test_release(p);
+               return 4;
+       }
+
+       p = bpf_kptr_xchg(&v->ref_ptr, p);
+       if (p) {
+               bpf_kfunc_call_test_release(p);
+               return 5;
+       }
+       if (p_st->cnt.refs.counter != 2)
+               return 6;
+
+       return 0;
+}
+
 char _license[] SEC("license") = "GPL";