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Message-ID: <20250506015857.817950-6-martin.lau@linux.dev>
Date: Mon, 5 May 2025 18:58:52 -0700
From: Martin KaFai Lau <martin.lau@...ux.dev>
To: bpf@...r.kernel.org
Cc: 'Alexei Starovoitov ' <ast@...nel.org>,
'Andrii Nakryiko ' <andrii@...nel.org>,
'Daniel Borkmann ' <daniel@...earbox.net>,
'Kumar Kartikeya Dwivedi ' <memxor@...il.com>,
'Amery Hung ' <ameryhung@...il.com>,
netdev@...r.kernel.org,
kernel-team@...a.com
Subject: [PATCH v2 bpf-next 5/8] selftests/bpf: Add tests for bpf_rbtree_{root,left,right}
From: Martin KaFai Lau <martin.lau@...nel.org>
This patch has a much simplified rbtree usage from the
kernel sch_fq qdisc. It has a "struct node_data" which can be
added to two different rbtrees which are ordered by different keys.
The test first populates both rbtrees. Then search for a lookup_key
from the "groot0" rbtree. Once the lookup_key is found, that node
refcount is taken. The node is then removed from another "groot1"
rbtree.
While searching the lookup_key, the test will also try to remove
all rbnodes in the path leading to the lookup_key.
The test_{root,left,right}_spinlock_true tests ensure that the
return value of the bpf_rbtree functions is a non_own_ref node pointer.
This is done by forcing an verifier error by calling a helper
bpf_jiffies64() while holding the spinlock. The tests then
check for the verifier message
"call bpf_rbtree...R0=rcu_ptr_or_null_node..."
The other test_{root,left,right}_spinlock_false tests ensure that
they must be called with spinlock held.
Suggested-by: Kumar Kartikeya Dwivedi <memxor@...il.com> # Check non_own_ref marking
Signed-off-by: Martin KaFai Lau <martin.lau@...nel.org>
---
.../testing/selftests/bpf/prog_tests/rbtree.c | 6 +
.../selftests/bpf/progs/rbtree_search.c | 206 ++++++++++++++++++
2 files changed, 212 insertions(+)
create mode 100644 tools/testing/selftests/bpf/progs/rbtree_search.c
diff --git a/tools/testing/selftests/bpf/prog_tests/rbtree.c b/tools/testing/selftests/bpf/prog_tests/rbtree.c
index 9818f06c97c5..d8f3d7a45fe9 100644
--- a/tools/testing/selftests/bpf/prog_tests/rbtree.c
+++ b/tools/testing/selftests/bpf/prog_tests/rbtree.c
@@ -8,6 +8,7 @@
#include "rbtree_fail.skel.h"
#include "rbtree_btf_fail__wrong_node_type.skel.h"
#include "rbtree_btf_fail__add_wrong_type.skel.h"
+#include "rbtree_search.skel.h"
static void test_rbtree_add_nodes(void)
{
@@ -187,3 +188,8 @@ void test_rbtree_fail(void)
{
RUN_TESTS(rbtree_fail);
}
+
+void test_rbtree_search(void)
+{
+ RUN_TESTS(rbtree_search);
+}
diff --git a/tools/testing/selftests/bpf/progs/rbtree_search.c b/tools/testing/selftests/bpf/progs/rbtree_search.c
new file mode 100644
index 000000000000..098ef970fac1
--- /dev/null
+++ b/tools/testing/selftests/bpf/progs/rbtree_search.c
@@ -0,0 +1,206 @@
+// SPDX-License-Identifier: GPL-2.0
+/* Copyright (c) 2025 Meta Platforms, Inc. and affiliates. */
+
+#include <vmlinux.h>
+#include <bpf/bpf_helpers.h>
+#include "bpf_misc.h"
+#include "bpf_experimental.h"
+
+struct node_data {
+ struct bpf_refcount ref;
+ struct bpf_rb_node r0;
+ struct bpf_rb_node r1;
+ int key0;
+ int key1;
+};
+
+#define private(name) SEC(".data." #name) __hidden __attribute__((aligned(8)))
+private(A) struct bpf_spin_lock glock0;
+private(A) struct bpf_rb_root groot0 __contains(node_data, r0);
+
+private(B) struct bpf_spin_lock glock1;
+private(B) struct bpf_rb_root groot1 __contains(node_data, r1);
+
+#define rb_entry(ptr, type, member) container_of(ptr, type, member)
+#define NR_NODES 16
+
+int zero = 0;
+
+static bool less0(struct bpf_rb_node *a, const struct bpf_rb_node *b)
+{
+ struct node_data *node_a;
+ struct node_data *node_b;
+
+ node_a = rb_entry(a, struct node_data, r0);
+ node_b = rb_entry(b, struct node_data, r0);
+
+ return node_a->key0 < node_b->key0;
+}
+
+static bool less1(struct bpf_rb_node *a, const struct bpf_rb_node *b)
+{
+ struct node_data *node_a;
+ struct node_data *node_b;
+
+ node_a = rb_entry(a, struct node_data, r1);
+ node_b = rb_entry(b, struct node_data, r1);
+
+ return node_a->key1 < node_b->key1;
+}
+
+SEC("syscall")
+__retval(0)
+long rbtree_search(void *ctx)
+{
+ struct bpf_rb_node *rb_n, *rb_m, *gc_ns[NR_NODES];
+ long lookup_key = NR_NODES / 2;
+ struct node_data *n, *m;
+ int i, nr_gc = 0;
+
+ for (i = zero; i < NR_NODES && can_loop; i++) {
+ n = bpf_obj_new(typeof(*n));
+ if (!n)
+ return __LINE__;
+
+ m = bpf_refcount_acquire(n);
+
+ n->key0 = i;
+ m->key1 = i;
+
+ bpf_spin_lock(&glock0);
+ bpf_rbtree_add(&groot0, &n->r0, less0);
+ bpf_spin_unlock(&glock0);
+
+ bpf_spin_lock(&glock1);
+ bpf_rbtree_add(&groot1, &m->r1, less1);
+ bpf_spin_unlock(&glock1);
+ }
+
+ n = NULL;
+ bpf_spin_lock(&glock0);
+ rb_n = bpf_rbtree_root(&groot0);
+ while (can_loop) {
+ if (!rb_n) {
+ bpf_spin_unlock(&glock0);
+ return __LINE__;
+ }
+
+ n = rb_entry(rb_n, struct node_data, r0);
+ if (lookup_key == n->key0)
+ break;
+ if (nr_gc < NR_NODES)
+ gc_ns[nr_gc++] = rb_n;
+ if (lookup_key < n->key0)
+ rb_n = bpf_rbtree_left(&groot0, rb_n);
+ else
+ rb_n = bpf_rbtree_right(&groot0, rb_n);
+ }
+
+ if (!n || lookup_key != n->key0) {
+ bpf_spin_unlock(&glock0);
+ return __LINE__;
+ }
+
+ for (i = 0; i < nr_gc; i++) {
+ rb_n = gc_ns[i];
+ gc_ns[i] = bpf_rbtree_remove(&groot0, rb_n);
+ }
+
+ m = bpf_refcount_acquire(n);
+ bpf_spin_unlock(&glock0);
+
+ for (i = 0; i < nr_gc; i++) {
+ rb_n = gc_ns[i];
+ if (rb_n) {
+ n = rb_entry(rb_n, struct node_data, r0);
+ bpf_obj_drop(n);
+ }
+ }
+
+ if (!m)
+ return __LINE__;
+
+ bpf_spin_lock(&glock1);
+ rb_m = bpf_rbtree_remove(&groot1, &m->r1);
+ bpf_spin_unlock(&glock1);
+ bpf_obj_drop(m);
+ if (!rb_m)
+ return __LINE__;
+ bpf_obj_drop(rb_entry(rb_m, struct node_data, r1));
+
+ return 0;
+}
+
+#define TEST_ROOT(dolock) \
+SEC("syscall") \
+__failure __msg(MSG) \
+long test_root_spinlock_##dolock(void *ctx) \
+{ \
+ struct bpf_rb_node *rb_n; \
+ __u64 jiffies = 0; \
+ \
+ if (dolock) \
+ bpf_spin_lock(&glock0); \
+ rb_n = bpf_rbtree_root(&groot0); \
+ if (rb_n) \
+ jiffies = bpf_jiffies64(); \
+ if (dolock) \
+ bpf_spin_unlock(&glock0); \
+ \
+ return !!jiffies; \
+}
+
+#define TEST_LR(op, dolock) \
+SEC("syscall") \
+__failure __msg(MSG) \
+long test_##op##_spinlock_##dolock(void *ctx) \
+{ \
+ struct bpf_rb_node *rb_n; \
+ struct node_data *n; \
+ __u64 jiffies = 0; \
+ \
+ bpf_spin_lock(&glock0); \
+ rb_n = bpf_rbtree_root(&groot0); \
+ if (!rb_n) { \
+ bpf_spin_unlock(&glock0); \
+ return 1; \
+ } \
+ n = rb_entry(rb_n, struct node_data, r0); \
+ n = bpf_refcount_acquire(n); \
+ bpf_spin_unlock(&glock0); \
+ if (!n) \
+ return 1; \
+ \
+ if (dolock) \
+ bpf_spin_lock(&glock0); \
+ rb_n = bpf_rbtree_##op(&groot0, &n->r0); \
+ if (rb_n) \
+ jiffies = bpf_jiffies64(); \
+ if (dolock) \
+ bpf_spin_unlock(&glock0); \
+ \
+ return !!jiffies; \
+}
+
+/*
+ * Use a spearate MSG macro instead of passing to TEST_XXX(..., MSG)
+ * to ensure the message itself is not in the bpf prog lineinfo
+ * which the verifier includes in its log.
+ * Otherwise, the test_loader will incorrectly match the prog lineinfo
+ * instead of the log generated by the verifier.
+ */
+#define MSG "call bpf_rbtree_root{{.+}}; R0{{(_w)?}}=rcu_ptr_or_null_node_data(id={{[0-9]+}},non_own_ref"
+TEST_ROOT(true)
+#undef MSG
+#define MSG "call bpf_rbtree_{{(left|right).+}}; R0{{(_w)?}}=rcu_ptr_or_null_node_data(id={{[0-9]+}},non_own_ref"
+TEST_LR(left, true)
+TEST_LR(right, true)
+#undef MSG
+
+#define MSG "bpf_spin_lock at off=0 must be held for bpf_rb_root"
+TEST_ROOT(false)
+TEST_LR(left, false)
+TEST_LR(right, false)
+#undef MSG
+
+char _license[] SEC("license") = "GPL";
--
2.47.1
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