From patchwork Fri Dec 30 04:11:51 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Hou Tao X-Patchwork-Id: 13084063 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8D5AEC4332F for ; Fri, 30 Dec 2022 04:12:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234024AbiL3EMP (ORCPT ); Thu, 29 Dec 2022 23:12:15 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37680 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234095AbiL3EMJ (ORCPT ); Thu, 29 Dec 2022 23:12:09 -0500 Received: from dggsgout12.his.huawei.com (unknown [45.249.212.56]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 7522A186C5; Thu, 29 Dec 2022 20:12:07 -0800 (PST) Received: from mail02.huawei.com (unknown [172.30.67.153]) by dggsgout12.his.huawei.com (SkyGuard) with ESMTP id 4NjsKF6DnKz4f3nqS; Fri, 30 Dec 2022 12:12:01 +0800 (CST) Received: from huaweicloud.com (unknown [10.175.124.27]) by APP4 (Coremail) with SMTP id gCh0CgAHcLMPZa5j3H4SAw--.35465S10; Fri, 30 Dec 2022 12:12:04 +0800 (CST) From: Hou Tao To: bpf@vger.kernel.org Cc: Martin KaFai Lau , Andrii Nakryiko , Song Liu , Hao Luo , Yonghong Song , Alexei Starovoitov , Daniel Borkmann , KP Singh , Stanislav Fomichev , Jiri Olsa , John Fastabend , "Paul E . McKenney" , rcu@vger.kernel.org, houtao1@huawei.com Subject: [RFC PATCH bpf-next 6/6] selftests/bpf: Add test case for element reuse in htab map Date: Fri, 30 Dec 2022 12:11:51 +0800 Message-Id: <20221230041151.1231169-7-houtao@huaweicloud.com> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20221230041151.1231169-1-houtao@huaweicloud.com> References: <20221230041151.1231169-1-houtao@huaweicloud.com> MIME-Version: 1.0 X-CM-TRANSID: gCh0CgAHcLMPZa5j3H4SAw--.35465S10 X-Coremail-Antispam: 1UD129KBjvJXoWxGw1DKw45Kr43GF1rWr13XFb_yoWrAF4Upa yrC34UKrWxXwn8Ww15Jan7KF4ftw1rZay5AFn3Ww1avw1UZr9avr1xKFW7tF1fCrZ3Xryr Zayfta15Zr48Cw7anT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUBSb4IE77IF4wAFF20E14v26rWj6s0DM7CY07I20VC2zVCF04k2 6cxKx2IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M28IrcIa0xkI8VA2jI8067AKxVWUAV Cq3wA2048vs2IY020Ec7CjxVAFwI0_Xr0E3s1l8cAvFVAK0II2c7xJM28CjxkF64kEwVA0 rcxSw2x7M28EF7xvwVC0I7IYx2IY67AKxVWDJVCq3wA2z4x0Y4vE2Ix0cI8IcVCY1x0267 AKxVW8Jr0_Cr1UM28EF7xvwVC2z280aVAFwI0_GcCE3s1l84ACjcxK6I8E87Iv6xkF7I0E 14v26rxl6s0DM2AIxVAIcxkEcVAq07x20xvEncxIr21l5I8CrVACY4xI64kE6c02F40Ex7 xfMcIj6xIIjxv20xvE14v26r1j6r18McIj6I8E87Iv67AKxVWUJVW8JwAm72CE4IkC6x0Y z7v_Jr0_Gr1lF7xvr2IYc2Ij64vIr41lFIxGxcIEc7CjxVA2Y2ka0xkIwI1l42xK82IYc2 Ij64vIr41l4I8I3I0E4IkC6x0Yz7v_Jr0_Gr1lx2IqxVAqx4xG67AKxVWUJVWUGwC20s02 6x8GjcxK67AKxVWUGVWUWwC2zVAF1VAY17CE14v26r1q6r43MIIYrxkI7VAKI48JMIIF0x vE2Ix0cI8IcVAFwI0_JFI_Gr1lIxAIcVC0I7IYx2IY6xkF7I0E14v26r4UJVWxJr1lIxAI cVCF04k26cxKx2IYs7xG6r1j6r1xMIIF0xvEx4A2jsIE14v26r1j6r4UMIIF0xvEx4A2js IEc7CjxVAFwI0_Gr1j6F4UJbIYCTnIWIevJa73UjIFyTuYvjxUFgAwUUUUU X-CM-SenderInfo: xkrx3t3r6k3tpzhluzxrxghudrp/ X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: rcu@vger.kernel.org From: Hou Tao The immediate reuse of free htab elements can lead to two problems: 1) lookup may get unexpected map value if the found element is deleted and then reused. 2) the reinitialization of spin-lock in map value after reuse may corrupt lookup with BPF_F_LOCK flag and result in hard lock-up. So add one test case to demonostrate these two problems. Signed-off-by: Hou Tao --- .../selftests/bpf/prog_tests/htab_reuse.c | 111 ++++++++++++++++++ .../testing/selftests/bpf/progs/htab_reuse.c | 19 +++ 2 files changed, 130 insertions(+) create mode 100644 tools/testing/selftests/bpf/prog_tests/htab_reuse.c create mode 100644 tools/testing/selftests/bpf/progs/htab_reuse.c diff --git a/tools/testing/selftests/bpf/prog_tests/htab_reuse.c b/tools/testing/selftests/bpf/prog_tests/htab_reuse.c new file mode 100644 index 000000000000..995972958d1d --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/htab_reuse.c @@ -0,0 +1,111 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (C) 2022. Huawei Technologies Co., Ltd */ +#define _GNU_SOURCE +#include +#include +#include +#include "htab_reuse.skel.h" + +struct htab_op_ctx { + int fd; + int loop; + bool stop; +}; + +struct htab_val { + unsigned int lock; + unsigned int data; +}; + +static void *htab_lookup_fn(void *arg) +{ + struct htab_op_ctx *ctx = arg; + int ret = 0, i = 0; + + while (i++ < ctx->loop && !ctx->stop) { + struct htab_val value; + unsigned int key; + int err; + + /* + * Use BPF_F_LOCK to use spin-lock in map value. And also + * check whether or not an unexpected value is returned. + */ + key = 7; + err = bpf_map_lookup_elem_flags(ctx->fd, &key, &value, BPF_F_LOCK); + if (!err && key != value.data) + ret = EINVAL; + } + + return (void *)(long)ret; +} + +static void *htab_update_fn(void *arg) +{ + struct htab_op_ctx *ctx = arg; + int i = 0; + + while (i++ < ctx->loop && !ctx->stop) { + struct htab_val value; + unsigned int key; + + key = 7; + value.lock = 0; + value.data = key; + bpf_map_update_elem(ctx->fd, &key, &value, BPF_F_LOCK); + bpf_map_delete_elem(ctx->fd, &key); + + key = 24; + value.lock = 0; + value.data = key; + bpf_map_update_elem(ctx->fd, &key, &value, BPF_F_LOCK); + bpf_map_delete_elem(ctx->fd, &key); + } + + return NULL; +} + +void test_htab_reuse(void) +{ + unsigned int i, wr_nr = 1, rd_nr = 4; + pthread_t tids[wr_nr + rd_nr]; + struct htab_reuse *skel; + struct htab_op_ctx ctx; + int err; + + skel = htab_reuse__open_and_load(); + if (!ASSERT_OK_PTR(skel, "htab_reuse__open_and_load")) + return; + + ctx.fd = bpf_map__fd(skel->maps.htab); + ctx.loop = 500; + ctx.stop = false; + + memset(tids, 0, sizeof(tids)); + for (i = 0; i < wr_nr; i++) { + err = pthread_create(&tids[i], NULL, htab_update_fn, &ctx); + if (!ASSERT_OK(err, "pthread_create")) { + ctx.stop = true; + goto reap; + } + } + for (i = 0; i < rd_nr; i++) { + err = pthread_create(&tids[i + wr_nr], NULL, htab_lookup_fn, &ctx); + if (!ASSERT_OK(err, "pthread_create")) { + ctx.stop = true; + goto reap; + } + } + +reap: + for (i = 0; i < wr_nr + rd_nr; i++) { + void *thread_err; + + if (!tids[i]) + continue; + thread_err = NULL; + pthread_join(tids[i], &thread_err); + ASSERT_NULL(thread_err, "thread error"); + } + htab_reuse__destroy(skel); +} diff --git a/tools/testing/selftests/bpf/progs/htab_reuse.c b/tools/testing/selftests/bpf/progs/htab_reuse.c new file mode 100644 index 000000000000..e6dcc70517f9 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/htab_reuse.c @@ -0,0 +1,19 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Copyright (C) 2022. Huawei Technologies Co., Ltd */ +#include +#include + +char _license[] SEC("license") = "GPL"; + +struct htab_val { + struct bpf_spin_lock lock; + unsigned int data; +}; + +struct { + __uint(type, BPF_MAP_TYPE_HASH); + __uint(max_entries, 64); + __type(key, unsigned int); + __type(value, struct htab_val); + __uint(map_flags, BPF_F_NO_PREALLOC); +} htab SEC(".maps");