From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wm2-f9.google.com (mail-wm2-f9.google.com [74.125.225.137]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8C3F546E005 for ; Fri, 4 Sep 2026 10:42:20 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=74.125.225.137 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788518545; cv=none; b=ZU+b+KJa5t5PfxsX9koITRGzG4VCzk4vnuphKXTLvXkRVI9fFPNPpxXCI2eYyD1poZng13qR6qdW4MJUdzGddHBMceQgpckYZPvFyi1JWYhYvBAbSVXNXZmESqw7e9mphiz2tW5KDoOBT6Rnv0n9WLy7JNJKK6dPIWfF3dYdtBE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788518545; c=relaxed/simple; bh=aJjbBBpoCRJCEu20JwRB5Rp9r+Jsz4MhltCNwI20Ubo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=rny7ozvrNsJ0xV9YK98uZoTVe8ZDvJ86yYGWzS4fjW1JVNUUZiQzKbk5ljcqV2Dy0dFOTB930qa7iiLFWglIAkgWStCLOmnJI8okJWnvEldbaqz4RwuWeEVXxFMbf0mCQgLioKeYNGaL54UCpcKPN6trr9IPy5Rma4OF1I8nJ7c= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=MPw7stCw; arc=none smtp.client-ip=74.125.225.137 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="MPw7stCw" Received: by mail-wm2-f9.google.com with SMTP id 5b1f17b1804b1-49556ce3549so4651875e9.0 for ; Fri, 04 Sep 2026 03:42:19 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20251104; t=1788518538; x=1789123338; darn=vger.kernel.org; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to:content-type; bh=+kN6d8+z8YVefS1D8RjSJPe3FWLFTdlv+E+aX4t1tOY=; b=MPw7stCwETN0m3uJYltjiDcFqK0whpf7J2cnp/LJLybJ5AVbAHw6tV/XyMKvQSZWcG lFtHuuluSV0h4vtCbfYWL0qRr9KYaMA3I0ienU+espf8xsjUnhYatIuB8qfmW3PcNfCS s6Z4LKu0fGMSBNEKrUiQ8GpvCUszIgoksvHv5UcikDYCUJD2SzAyQsVI+OUmYer8hiCx LmmQUYHEowr0wa9yjii9/6Z7qCcDwQv4Ds4RX5Jn08FA9Y7W6YjHOL78IOf4MDJbNoXk jw/7WEmB2VKOL2dmMz2uP4UZkQLMR/5TRtqIRI1hKDROYZxgBC7hBbbyC6a/FsH+acgP Y1AQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1788518538; x=1789123338; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-gg:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to:content-type; bh=+kN6d8+z8YVefS1D8RjSJPe3FWLFTdlv+E+aX4t1tOY=; b=K/2ZN0JltCz8esim0s8E/9APf2Op+uBNG35sB6C3sSqawXvKiW/qhjul+sO//zbO+f YpMVnPqU6GSrG4Tnfgg03uV2vCvFcPKeWLXgIr6UHpnaHre17OUgnvFG0o2SeQVIm50J 86VForOAqQyRMNLtQ4jUbjLJH14t7FQktfPfRcoEFOUy2H3Ey3KcFxwHnn4LhGyTAzxv eztnD8ugCHq7DqpqOwRalc387Rfl6iR63Xs/+xHcqXqENiVKLaEr41usI8UKvaQOdsJo a6om6xlW4zyxcIzb6mo9Jl9hBn6+lHx3oRePVh5dsSepivlJzISHWhoDe8ChPWbxfhic 8Upg== X-Gm-Message-State: AFuF++mCDv+QqELUwPbNBjZ1mzvJo5rUXcPhiVqpzKMFwXyHiyrXG3RG AbYsTBdoL4FTOvk32QZYHnFfN7mnQd86WCTfecefbEMUJmWQc2zvA9fsUzsnlEd1 X-Gm-Gg: AYBFou17rIEiW/IuGJYuxybbUWLzwP6x6ixw6R4InavECVzGJpqPIUKuupmWc1jdw1u 4gs5BAEeSHq4/Hdq719jtaT1KuqE8Z7KJ1ePMdM63hxV/bNHrug/uCdUB0CAFbhphoZMEZIOUQC oC962j+OhMZ/CtpROkdljXCWBhAJbxZQIotA5JmVnDdGLoFLRoksXvoNiqHyjn9Nt/WNOu/gPXg PM7Be5cbvComrRWm7Ig/23Xvx6xRno0imHIzSzXb+W2215flc6Jo86qY0RRxoF+NLvveVQz44FO zxXgaYJb4EPaa/yBs0EX5e3kcJVC+QoU/EfCZP9j/k7uhUumV3Tztb+EBImNE6FAEjGmhx6UYVp xe++NZJZOk7ng+IHcuB/iZkVVl8YOa12TqxmKqR8LrQALWaP64QrkiBfTkjp1H6zbQx1ZwEzjJm p9NJSA7vYvq1nwoLuP+T9OA6hQ/dO8LnQXZjK6D3DNHhwid15o8Be2aew+WnjC1QNI27RWQbOHZ SFuARw3GTJF6RwDliY69ANDgqf0eaxjNFrQpk/vGpuLan/2Sj/TXmxU4cU6Uf8xONgigLAW8Ix0 RLh/5D0iWavvHG6bDmytWSai764= X-Received: by 2002:a05:600c:35c3:b0:49c:fc6c:be10 with SMTP id 5b1f17b1804b1-49cfc6cc055mr23647675e9.22.1788518537966; Fri, 04 Sep 2026 03:42:17 -0700 (PDT) Received: from localhost (nat-icclus-192-26-29-3.epfl.ch. [192.26.29.3]) by smtp.gmail.com with ESMTPSA id 5b1f17b1804b1-49cf7740d44sm130283925e9.15.2026.09.04.03.42.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 04 Sep 2026 03:42:17 -0700 (PDT) From: Kumar Kartikeya Dwivedi To: bpf@vger.kernel.org Cc: Alexei Starovoitov , Andrii Nakryiko , Daniel Borkmann , Eduard Zingerman , Emil Tsalapatis , Nicholas Carlini , kkd@meta.com, kernel-team@meta.com Subject: [PATCH bpf v1 2/8] selftests/bpf: Test timer field on recycled rhtab element Date: Fri, 4 Sep 2026 12:41:53 +0200 Message-ID: <20260904104203.345917-3-memxor@gmail.com> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260904104203.345917-1-memxor@gmail.com> References: <20260904104203.345917-1-memxor@gmail.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=7329; i=memxor@gmail.com; h=from:subject; bh=aJjbBBpoCRJCEu20JwRB5Rp9r+Jsz4MhltCNwI20Ubo=; b=owGbwMvMwCXmrmtenRyi38x4Wi2JIWvW/LMm7sY35otkxc/fk6sb5fSyNpiBtbDz991T3JqP7 +YFlcztKGVhEONikBVTZCn5v4/J+ETl70DbZdwwc1iZQIYwcHEKwETmPWP479e0kmlu66ctVruT 7Vd2fljgM98xakEQn3ugoeqru+HB3xkZLn5l0vkVtOQ0l2CHwfNLr87eSfnKom/rp9azYt50a5G bLAA= X-Developer-Key: i=memxor@gmail.com; a=openpgp; fpr=B34BD741DE8494B76E2F717880EF20021D46C59B Content-Transfer-Encoding: 8bit Exercise the rhtab special-field lifecycle with the sequence from the original report. A bpf_for_each_map_elem() callback deletes the sole element, then initializes and arms a timer through the callback value pointer while it remains valid. Use a one-element map and pin userspace and BPF execution to one CPU. Repeated delete-and-replace cycles drain the per-CPU allocator cache, and periodic RCU synchronization makes the deleted units available for recycling. After each replacement, a second BPF program calls bpf_timer_cancel() on its value. A successful cancellation proves both that a timer-bearing unit was recycled and that insertion preserved the timer field. Without the fix, insertion clears that field and cancellation keeps returning -EINVAL. A long expiration keeps the timer callback out of the test, so the regression is detected without accessing freed memory. Signed-off-by: Kumar Kartikeya Dwivedi --- .../selftests/bpf/prog_tests/rhash_timer.c | 141 ++++++++++++++++++ .../testing/selftests/bpf/progs/rhash_timer.c | 98 ++++++++++++ 2 files changed, 239 insertions(+) create mode 100644 tools/testing/selftests/bpf/prog_tests/rhash_timer.c create mode 100644 tools/testing/selftests/bpf/progs/rhash_timer.c diff --git a/tools/testing/selftests/bpf/prog_tests/rhash_timer.c b/tools/testing/selftests/bpf/prog_tests/rhash_timer.c new file mode 100644 index 000000000000..3aad9fc02e06 --- /dev/null +++ b/tools/testing/selftests/bpf/prog_tests/rhash_timer.c @@ -0,0 +1,141 @@ +// SPDX-License-Identifier: GPL-2.0 + +#define _GNU_SOURCE +#include + +#include +#include "rhash_timer.skel.h" + +#define MAX_ATTEMPTS 256 +#define RCU_SYNC_INTERVAL 64 + +static int pin_to_first_cpu(cpu_set_t *old_mask) +{ + cpu_set_t new_mask; + int cpu; + + if (sched_getaffinity(0, sizeof(*old_mask), old_mask)) + return -errno; + + for (cpu = 0; cpu < CPU_SETSIZE; cpu++) + if (CPU_ISSET(cpu, old_mask)) + break; + if (cpu == CPU_SETSIZE) + return -EINVAL; + + CPU_ZERO(&new_mask); + CPU_SET(cpu, &new_mask); + if (sched_setaffinity(0, sizeof(new_mask), &new_mask)) + return -errno; + return 0; +} + +static int update_timer_map(int map_fd, __u64 key) +{ + __u64 value[3] = {}; + + return bpf_map_update_elem(map_fd, &key, value, BPF_NOEXIST); +} + +static int run_prog(int prog_fd, struct bpf_test_run_opts *opts) +{ + int err; + + err = bpf_prog_test_run_opts(prog_fd, opts); + if (err) + return err; + return opts->retval; +} + +void test_rhash_timer(void) +{ + LIBBPF_OPTS(bpf_test_run_opts, opts); + struct rhash_timer *skel = NULL; + cpu_set_t old_mask; + int map_fd = -1, arm_fd, cancel_fd; + bool affinity_set = false; + __u64 key = 1; + int attempt, err; + + err = pin_to_first_cpu(&old_mask); + if (!ASSERT_OK(err, "pin_to_first_cpu")) + return; + affinity_set = true; + + skel = rhash_timer__open_and_load(); + if (!ASSERT_OK_PTR(skel, "open_and_load")) + goto out; + + map_fd = bpf_map__fd(skel->maps.timer_map); + if (!ASSERT_GE(map_fd, 0, "timer_map fd")) + goto out; + arm_fd = bpf_program__fd(skel->progs.arm_deleted_timer); + if (!ASSERT_GE(arm_fd, 0, "arm_deleted_timer fd")) + goto out; + cancel_fd = bpf_program__fd(skel->progs.cancel_recycled_timer); + if (!ASSERT_GE(cancel_fd, 0, "cancel_recycled_timer fd")) + goto out; + + err = update_timer_map(map_fd, key); + if (!ASSERT_OK(err, "seed_timer_map")) + goto out; + + for (attempt = 0; attempt < MAX_ATTEMPTS; attempt++) { + err = run_prog(arm_fd, &opts); + if (err) { + ASSERT_OK(err, "arm_deleted_timer"); + goto out; + } + if (skel->bss->armed != attempt + 1) { + ASSERT_EQ(skel->bss->armed, attempt + 1, "armed"); + goto out; + } + if (skel->bss->timer_init_err) { + ASSERT_OK(skel->bss->timer_init_err, "timer_init_err"); + goto out; + } + if (skel->bss->timer_set_callback_err) { + ASSERT_OK(skel->bss->timer_set_callback_err, + "timer_set_callback_err"); + goto out; + } + if (skel->bss->timer_start_err) { + ASSERT_OK(skel->bss->timer_start_err, "timer_start_err"); + goto out; + } + + if ((attempt + 1) % RCU_SYNC_INTERVAL == 0) { + err = kern_sync_rcu(); + if (err) { + ASSERT_OK(err, "kern_sync_rcu"); + goto out; + } + } + + err = update_timer_map(map_fd, ++key); + if (err) { + ASSERT_OK(err, "replace_timer_map"); + goto out; + } + + err = run_prog(cancel_fd, &opts); + if (err) { + ASSERT_OK(err, "cancel_recycled_timer"); + goto out; + } + if (skel->bss->timer_cancel_err) { + ASSERT_OK(skel->bss->timer_cancel_err, "timer_cancel_err"); + goto out; + } + if (skel->bss->cancelled) + break; + } + + ASSERT_GT(skel->bss->cancelled, 0, "preserved timer"); +out: + if (map_fd >= 0) + bpf_map_delete_elem(map_fd, &key); + rhash_timer__destroy(skel); + if (affinity_set) + sched_setaffinity(0, sizeof(old_mask), &old_mask); +} diff --git a/tools/testing/selftests/bpf/progs/rhash_timer.c b/tools/testing/selftests/bpf/progs/rhash_timer.c new file mode 100644 index 000000000000..2e06a463c605 --- /dev/null +++ b/tools/testing/selftests/bpf/progs/rhash_timer.c @@ -0,0 +1,98 @@ +// SPDX-License-Identifier: GPL-2.0 + +#include +#include +#include + +#define CLOCK_MONOTONIC 1 +#define TIMER_NSEC (60ULL * 1000 * 1000 * 1000) + +struct timer_value { + struct bpf_timer timer; + u64 data; +}; + +struct { + __uint(type, BPF_MAP_TYPE_RHASH); + __uint(map_flags, BPF_F_NO_PREALLOC); + __uint(max_entries, 1); + __type(key, u64); + __type(value, struct timer_value); +} timer_map SEC(".maps"); + +u64 armed; +u64 cancelled; +long timer_init_err; +long timer_set_callback_err; +long timer_start_err; +long timer_cancel_err; + +static int timer_cb(void *map, u64 *key, struct timer_value *value) +{ + return 0; +} + +static long arm_timer_cb(struct bpf_map *map, u64 *key, + struct timer_value *value, void *ctx) +{ + u64 key_copy = *key; + long err; + + err = bpf_map_delete_elem(map, &key_copy); + if (err) + return 1; + + err = bpf_timer_init(&value->timer, map, CLOCK_MONOTONIC); + if (err) { + timer_init_err = err; + return 1; + } + + err = bpf_timer_set_callback(&value->timer, timer_cb); + if (err) { + timer_set_callback_err = err; + return 1; + } + + err = bpf_timer_start(&value->timer, TIMER_NSEC, BPF_F_TIMER_CPU_PIN); + if (err) { + timer_start_err = err; + return 1; + } + + __sync_fetch_and_add(&armed, 1); + return 1; +} + +static long cancel_timer_cb(struct bpf_map *map, u64 *key, + struct timer_value *value, void *ctx) +{ + long err; + + err = bpf_timer_cancel(&value->timer); + if (err == -EINVAL) + return 1; + if (err < 0) { + timer_cancel_err = err; + return 1; + } + + __sync_fetch_and_add(&cancelled, 1); + return 1; +} + +SEC("syscall") +int arm_deleted_timer(void *ctx) +{ + bpf_for_each_map_elem(&timer_map, arm_timer_cb, NULL, 0); + return 0; +} + +SEC("syscall") +int cancel_recycled_timer(void *ctx) +{ + bpf_for_each_map_elem(&timer_map, cancel_timer_cb, NULL, 0); + return 0; +} + +char _license[] SEC("license") = "GPL"; -- 2.53.0