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selftests/bpf: Add tests for bpf_rbtree_{root,left,right}
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@gmail.com> # Check non_own_ref marking
Signed-off-by: Martin KaFai Lau <martin.lau@kernel.org>
Link: https://lore.kernel.org/r/20250506015857.817950-6-martin.lau@linux.dev
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Martin KaFai Lau
Alexei Starovoitov
parent
2ddef1783c
commit
47ada65c5c
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@ -8,6 +8,7 @@
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#include "rbtree_fail.skel.h"
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#include "rbtree_btf_fail__wrong_node_type.skel.h"
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#include "rbtree_btf_fail__add_wrong_type.skel.h"
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#include "rbtree_search.skel.h"
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static void test_rbtree_add_nodes(void)
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{
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@ -187,3 +188,8 @@ void test_rbtree_fail(void)
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{
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RUN_TESTS(rbtree_fail);
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}
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void test_rbtree_search(void)
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{
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RUN_TESTS(rbtree_search);
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}
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206
tools/testing/selftests/bpf/progs/rbtree_search.c
Normal file
206
tools/testing/selftests/bpf/progs/rbtree_search.c
Normal file
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@ -0,0 +1,206 @@
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// SPDX-License-Identifier: GPL-2.0
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/* Copyright (c) 2025 Meta Platforms, Inc. and affiliates. */
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#include <vmlinux.h>
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#include <bpf/bpf_helpers.h>
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#include "bpf_misc.h"
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#include "bpf_experimental.h"
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struct node_data {
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struct bpf_refcount ref;
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struct bpf_rb_node r0;
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struct bpf_rb_node r1;
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int key0;
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int key1;
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};
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#define private(name) SEC(".data." #name) __hidden __attribute__((aligned(8)))
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private(A) struct bpf_spin_lock glock0;
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private(A) struct bpf_rb_root groot0 __contains(node_data, r0);
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private(B) struct bpf_spin_lock glock1;
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private(B) struct bpf_rb_root groot1 __contains(node_data, r1);
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#define rb_entry(ptr, type, member) container_of(ptr, type, member)
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#define NR_NODES 16
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int zero = 0;
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static bool less0(struct bpf_rb_node *a, const struct bpf_rb_node *b)
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{
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struct node_data *node_a;
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struct node_data *node_b;
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node_a = rb_entry(a, struct node_data, r0);
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node_b = rb_entry(b, struct node_data, r0);
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return node_a->key0 < node_b->key0;
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}
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static bool less1(struct bpf_rb_node *a, const struct bpf_rb_node *b)
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{
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struct node_data *node_a;
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struct node_data *node_b;
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node_a = rb_entry(a, struct node_data, r1);
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node_b = rb_entry(b, struct node_data, r1);
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return node_a->key1 < node_b->key1;
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}
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SEC("syscall")
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__retval(0)
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long rbtree_search(void *ctx)
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{
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struct bpf_rb_node *rb_n, *rb_m, *gc_ns[NR_NODES];
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long lookup_key = NR_NODES / 2;
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struct node_data *n, *m;
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int i, nr_gc = 0;
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for (i = zero; i < NR_NODES && can_loop; i++) {
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n = bpf_obj_new(typeof(*n));
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if (!n)
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return __LINE__;
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m = bpf_refcount_acquire(n);
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n->key0 = i;
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m->key1 = i;
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bpf_spin_lock(&glock0);
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bpf_rbtree_add(&groot0, &n->r0, less0);
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bpf_spin_unlock(&glock0);
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bpf_spin_lock(&glock1);
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bpf_rbtree_add(&groot1, &m->r1, less1);
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bpf_spin_unlock(&glock1);
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}
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n = NULL;
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bpf_spin_lock(&glock0);
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rb_n = bpf_rbtree_root(&groot0);
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while (can_loop) {
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if (!rb_n) {
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bpf_spin_unlock(&glock0);
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return __LINE__;
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}
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n = rb_entry(rb_n, struct node_data, r0);
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if (lookup_key == n->key0)
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break;
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if (nr_gc < NR_NODES)
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gc_ns[nr_gc++] = rb_n;
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if (lookup_key < n->key0)
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rb_n = bpf_rbtree_left(&groot0, rb_n);
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else
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rb_n = bpf_rbtree_right(&groot0, rb_n);
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}
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if (!n || lookup_key != n->key0) {
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bpf_spin_unlock(&glock0);
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return __LINE__;
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}
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for (i = 0; i < nr_gc; i++) {
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rb_n = gc_ns[i];
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gc_ns[i] = bpf_rbtree_remove(&groot0, rb_n);
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}
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m = bpf_refcount_acquire(n);
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bpf_spin_unlock(&glock0);
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for (i = 0; i < nr_gc; i++) {
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rb_n = gc_ns[i];
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if (rb_n) {
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n = rb_entry(rb_n, struct node_data, r0);
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bpf_obj_drop(n);
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}
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}
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if (!m)
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return __LINE__;
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bpf_spin_lock(&glock1);
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rb_m = bpf_rbtree_remove(&groot1, &m->r1);
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bpf_spin_unlock(&glock1);
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bpf_obj_drop(m);
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if (!rb_m)
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return __LINE__;
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bpf_obj_drop(rb_entry(rb_m, struct node_data, r1));
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return 0;
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}
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#define TEST_ROOT(dolock) \
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SEC("syscall") \
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__failure __msg(MSG) \
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long test_root_spinlock_##dolock(void *ctx) \
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{ \
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struct bpf_rb_node *rb_n; \
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__u64 jiffies = 0; \
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\
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if (dolock) \
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bpf_spin_lock(&glock0); \
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rb_n = bpf_rbtree_root(&groot0); \
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if (rb_n) \
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jiffies = bpf_jiffies64(); \
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if (dolock) \
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bpf_spin_unlock(&glock0); \
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\
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return !!jiffies; \
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}
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#define TEST_LR(op, dolock) \
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SEC("syscall") \
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__failure __msg(MSG) \
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long test_##op##_spinlock_##dolock(void *ctx) \
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{ \
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struct bpf_rb_node *rb_n; \
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struct node_data *n; \
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__u64 jiffies = 0; \
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\
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bpf_spin_lock(&glock0); \
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rb_n = bpf_rbtree_root(&groot0); \
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if (!rb_n) { \
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bpf_spin_unlock(&glock0); \
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return 1; \
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} \
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n = rb_entry(rb_n, struct node_data, r0); \
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n = bpf_refcount_acquire(n); \
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bpf_spin_unlock(&glock0); \
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if (!n) \
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return 1; \
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\
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if (dolock) \
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bpf_spin_lock(&glock0); \
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rb_n = bpf_rbtree_##op(&groot0, &n->r0); \
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if (rb_n) \
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jiffies = bpf_jiffies64(); \
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if (dolock) \
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bpf_spin_unlock(&glock0); \
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\
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return !!jiffies; \
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}
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/*
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* Use a spearate MSG macro instead of passing to TEST_XXX(..., MSG)
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* to ensure the message itself is not in the bpf prog lineinfo
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* which the verifier includes in its log.
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* Otherwise, the test_loader will incorrectly match the prog lineinfo
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* instead of the log generated by the verifier.
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*/
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#define MSG "call bpf_rbtree_root{{.+}}; R0{{(_w)?}}=rcu_ptr_or_null_node_data(id={{[0-9]+}},non_own_ref"
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TEST_ROOT(true)
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#undef MSG
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#define MSG "call bpf_rbtree_{{(left|right).+}}; R0{{(_w)?}}=rcu_ptr_or_null_node_data(id={{[0-9]+}},non_own_ref"
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TEST_LR(left, true)
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TEST_LR(right, true)
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#undef MSG
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#define MSG "bpf_spin_lock at off=0 must be held for bpf_rb_root"
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TEST_ROOT(false)
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TEST_LR(left, false)
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TEST_LR(right, false)
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#undef MSG
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char _license[] SEC("license") = "GPL";
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