From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-174.mta1.migadu.com (out-174.mta1.migadu.com [95.215.58.174]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 495C05695 for ; Fri, 7 Nov 2025 02:00:28 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.174 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762480830; cv=none; b=u8Mr/XmWa23TJg7oY6ilx0Wy9KxXjd3iZL6tfhohqBR5bZjwTn5brOSvLBjDYtRBdj5LhS/rnwEnMv4l9frjBrYb/ygRaTTmzoSVn8bNqoWAO/JLGNXY2EVBiiMCjQ6c4FsSMbPHmZkiAcvcQYn21v+AnG7vJn7PJp3bLoUCPCw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1762480830; c=relaxed/simple; bh=l1APtHG7nyKthnsB6Dpo0ioWvJx4fIPPEtLcFliwVnI=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=TyRh1RPnxc77ik5oxeU4ITEfv1suMtOB3TZoEgjJoaL3BGbAWhMOt2L1Krom5w51bSsyE5bxf7hLsXFWnZRdmwudLva27TDNYHE1a7JivHSabtLowdWptYwTusURd8VGfYpbgrEVaVGoRj8KyGI7PkrRQxLaIY5WQQbX8UeZ6FI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=lryL4Pjc; arc=none smtp.client-ip=95.215.58.174 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="lryL4Pjc" Message-ID: <9f662e2c-7370-4f99-bdec-bc123495e1c5@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1762480826; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=ZNhsVywyT7lcCq3rJ86s3fFpmqzt3mLICMXhAupeVE4=; b=lryL4PjcLr2/8OwCkdAtMVoDM65Ga5Txb1eNj9xYXA/UogiTwytyxWh4ur3bZDIwvnQBVO huJYa/KcwvpZJypWHrcMcOpd01eHDTJcZ4iq+TGgE17oRuXitaA9oQ9uL4MVcrzVHVgr7j 2Rrjw6yq+aQmDMiRQq14RsSi0W7yHUg= Date: Thu, 6 Nov 2025 18:00:17 -0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH bpf-next v6 2/2] selftests/bpf: Add test to verify freeing the special fields when update [lru_,]percpu_hash maps Content-Language: en-GB To: Leon Hwang , bpf@vger.kernel.org Cc: ast@kernel.org, andrii@kernel.org, daniel@iogearbox.net, martin.lau@linux.dev, eddyz87@gmail.com, song@kernel.org, john.fastabend@gmail.com, kpsingh@kernel.org, sdf@fomichev.me, haoluo@google.com, jolsa@kernel.org, memxor@gmail.com, ameryhung@gmail.com, linux-kernel@vger.kernel.org, kernel-patches-bot@fb.com References: <20251105151407.12723-1-leon.hwang@linux.dev> <20251105151407.12723-3-leon.hwang@linux.dev> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Yonghong Song In-Reply-To: <20251105151407.12723-3-leon.hwang@linux.dev> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT On 11/5/25 7:14 AM, Leon Hwang wrote: > Add test to verify that updating [lru_,]percpu_hash maps decrements > refcount when BPF_KPTR_REF objects are involved. > > The tests perform the following steps: > > 1. Call update_elem() to insert an initial value. > 2. Use bpf_refcount_acquire() to increment the refcount. > 3. Store the node pointer in the map value. > 4. Add the node to a linked list. > 5. Probe-read the refcount and verify it is *2*. > 6. Call update_elem() again to trigger refcount decrement. > 7. Probe-read the refcount and verify it is *1*. > > Signed-off-by: Leon Hwang LGTM with a few nits below. Acked-by: Yonghong Song > --- > .../bpf/prog_tests/refcounted_kptr.c | 57 ++++++++++++++++++ > .../selftests/bpf/progs/refcounted_kptr.c | 60 +++++++++++++++++++ > 2 files changed, 117 insertions(+) > > diff --git a/tools/testing/selftests/bpf/prog_tests/refcounted_kptr.c b/tools/testing/selftests/bpf/prog_tests/refcounted_kptr.c > index d6bd5e16e6372..086f679fa3f61 100644 > --- a/tools/testing/selftests/bpf/prog_tests/refcounted_kptr.c > +++ b/tools/testing/selftests/bpf/prog_tests/refcounted_kptr.c > @@ -44,3 +44,60 @@ void test_refcounted_kptr_wrong_owner(void) > ASSERT_OK(opts.retval, "rbtree_wrong_owner_remove_fail_a2 retval"); > refcounted_kptr__destroy(skel); > } > + > +void test_percpu_hash_refcounted_kptr_refcount_leak(void) > +{ > + struct refcounted_kptr *skel; > + int cpu_nr, fd, err, key = 0; > + struct bpf_map *map; > + size_t values_sz; > + u64 *values; > + LIBBPF_OPTS(bpf_test_run_opts, opts, > + .data_in = &pkt_v4, > + .data_size_in = sizeof(pkt_v4), > + .repeat = 1, > + ); > + > + cpu_nr = libbpf_num_possible_cpus(); > + if (!ASSERT_GT(cpu_nr, 0, "libbpf_num_possible_cpus")) > + return; > + > + values = calloc(cpu_nr, sizeof(u64)); > + if (!ASSERT_OK_PTR(values, "calloc values")) > + return; > + > + skel = refcounted_kptr__open_and_load(); > + if (!ASSERT_OK_PTR(skel, "refcounted_kptr__open_and_load")) { > + free(values); > + return; > + } > + > + values_sz = cpu_nr * sizeof(u64); > + memset(values, 0, values_sz); > + > + map = skel->maps.percpu_hash; > + err = bpf_map__update_elem(map, &key, sizeof(key), values, values_sz, 0); > + if (!ASSERT_OK(err, "bpf_map__update_elem")) > + goto out; > + > + fd = bpf_program__fd(skel->progs.percpu_hash_refcount_leak); > + err = bpf_prog_test_run_opts(fd, &opts); > + if (!ASSERT_OK(err, "bpf_prog_test_run_opts")) > + goto out; > + if (!ASSERT_EQ(opts.retval, 2, "opts.retval")) > + goto out; > + > + err = bpf_map__update_elem(map, &key, sizeof(key), values, values_sz, 0); > + if (!ASSERT_OK(err, "bpf_map__update_elem")) > + goto out; > + > + fd = bpf_program__fd(skel->progs.check_percpu_hash_refcount); > + err = bpf_prog_test_run_opts(fd, &opts); > + ASSERT_OK(err, "bpf_prog_test_run_opts"); > + ASSERT_EQ(opts.retval, 1, "opts.retval"); > + > +out: > + refcounted_kptr__destroy(skel); > + free(values); > +} > + Empty line here. > diff --git a/tools/testing/selftests/bpf/progs/refcounted_kptr.c b/tools/testing/selftests/bpf/progs/refcounted_kptr.c > index 893a4fdb4b6e9..1aca85d86aebc 100644 > --- a/tools/testing/selftests/bpf/progs/refcounted_kptr.c > +++ b/tools/testing/selftests/bpf/progs/refcounted_kptr.c > @@ -568,4 +568,64 @@ int BPF_PROG(rbtree_sleepable_rcu_no_explicit_rcu_lock, > return 0; > } > > +private(kptr_ref) u64 ref; > + > +static int probe_read_refcount(void) > +{ > + u32 refcount; > + > + bpf_probe_read_kernel(&refcount, sizeof(refcount), (void *) ref); > + return refcount; > +} > + > +static int __insert_in_list(struct bpf_list_head *head, struct bpf_spin_lock *lock, > + struct node_data __kptr **node) > +{ > + struct node_data *node_new, *node_ref, *node_old; > + > + node_new = bpf_obj_new(typeof(*node_new)); > + if (!node_new) > + return -1; > + > + node_ref = bpf_refcount_acquire(node_new); > + node_old = bpf_kptr_xchg(node, node_new); Change the above to node_old = bpf_kptr_xchg(node, node_node_ref); might be better for reasoning although node_ref/node_new are the same. > + if (node_old) { > + bpf_obj_drop(node_old); > + bpf_obj_drop(node_ref); > + return -2; > + } > + > + bpf_spin_lock(lock); > + bpf_list_push_front(head, &node_ref->l); > + ref = (u64)(void *) &node_ref->ref; > + bpf_spin_unlock(lock); > + return probe_read_refcount(); > +} > + > +struct { > + __uint(type, BPF_MAP_TYPE_PERCPU_HASH); > + __type(key, int); > + __type(value, struct map_value); > + __uint(max_entries, 1); > +} percpu_hash SEC(".maps"); > + > +SEC("tc") > +int percpu_hash_refcount_leak(void *ctx) > +{ > + struct map_value *v; > + int key = 0; > + > + v = bpf_map_lookup_elem(&percpu_hash, &key); > + if (!v) > + return 0; > + > + return __insert_in_list(&head, &lock, &v->node); > +} > + > +SEC("tc") > +int check_percpu_hash_refcount(void *ctx) > +{ > + return probe_read_refcount(); > +} > + > char _license[] SEC("license") = "GPL";