From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-178.mta0.migadu.com (out-178.mta0.migadu.com [91.218.175.178]) (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 4ADFF1640B for ; Fri, 12 Jan 2024 19:47:54 +0000 (UTC) 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="WRityevg" Message-ID: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1705088872; 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=z/VqR5Xhj2JZIvBYaCc6cE9Whg2FaHGC6zQ47S6eL2Q=; b=WRityevgduaYEAciU7zS1MLAQR4/Rgc2mOJaMAVkUQ0g5KS6U3rfzm6qkxAa/WJcZwLwY1 6T1XydFd1i/1cb3Y9eoK84j5OueZDoJkBq79SvvBQfW79M3sL7MvrJoI//0s9r3IIEemV0 OC7EesNWUOKWZvEEAW411PKLMl3ZbgU= Date: Fri, 12 Jan 2024 11:47:48 -0800 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH bpf v2] libbpf: Apply map_set_def_max_entries() for inner_maps on creation Content-Language: en-US To: Andrey Grafin Cc: andrii@kernel.org, bpf@vger.kernel.org, Yonghong Song References: <20240112121051.17325-1-conquistador@yandex-team.ru> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Martin KaFai Lau In-Reply-To: <20240112121051.17325-1-conquistador@yandex-team.ru> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Migadu-Flow: FLOW_OUT On 1/12/24 4:10 AM, Andrey Grafin wrote: > This patch allows to create BPF_MAP_TYPE_ARRAY_OF_MAPS and > BPF_MAP_TYPE_HASH_OF_MAPS with values of BPF_MAP_TYPE_PERF_EVENT_ARRAY. > > Previous behaviour created a zero filled btf_map_def for inner maps and > tried to use it for a map creation but the linux kernel forbids to create > a BPF_MAP_TYPE_PERF_EVENT_ARRAY map with max_entries=0. > > A simple bpf snippet to reproduce: > struct inner_map { > __uint(type, BPF_MAP_TYPE_PERF_EVENT_ARRAY); > __uint(key_size, sizeof(int)); > __uint(value_size, sizeof(u32)); > } inner_map0 SEC(".maps"), inner_map1 SEC(".maps"); > > struct { > __uint(type, BPF_MAP_TYPE_ARRAY_OF_MAPS); > __uint(max_entries, 2); > __type(key, u32); > __array(values, struct inner_map); > } outer_map SEC(".maps") = { > .values = {&inner_map0, &inner_map1}}; > ... > > Previous behaviour: > # sudo bpftool prog load ./bpf_sample.elf /sys/fs/bpf/test > libbpf: map 'outer_map': failed to create inner map: -22 > libbpf: map 'outer_map': failed to create: Invalid argument(-22) > libbpf: failed to load object './bpf_sample.elf' > Error: failed to load object file > > # sudo strace -e bpf bpftool prog load ./bpf_sample.elf /sys/fs/bpf/test > ... > bpf(BPF_MAP_CREATE, {map_type=BPF_MAP_TYPE_PERF_EVENT_ARRAY, key_size=4, > value_size=4, max_entries=16, map_flags=0, inner_map_fd=0, > map_name="inner_map0", map_ifindex=0, btf_fd=0, btf_key_type_id=0, > btf_value_type_id=0, btf_vmlinux_value_type_id=0, map_extra=0}, 72) = 4 > bpf(BPF_MAP_CREATE, {map_type=BPF_MAP_TYPE_PERF_EVENT_ARRAY, key_size=4, > value_size=4, max_entries=16, map_flags=0, inner_map_fd=0, > map_name="inner_map1", map_ifindex=0, btf_fd=0, btf_key_type_id=0, > btf_value_type_id=0, btf_vmlinux_value_type_id=0, map_extra=0}, 72) = 5 > bpf(BPF_MAP_CREATE, {map_type=BPF_MAP_TYPE_PERF_EVENT_ARRAY, key_size=4, > value_size=4, max_entries=0, map_flags=0, inner_map_fd=0, > map_name="outer_map.inner", map_ifindex=0, btf_fd=0, > btf_key_type_id=0, btf_value_type_id=0, btf_vmlinux_value_type_id=0, > map_extra=0}, 72) = -1 EINVAL (Invalid argument) The change makes sense. Please help to add a real selftest to catch future regression. I believe it is what Yonghong has already asked in v1. Some of the existing "progs/*map_in_map*.c" may be a good candidate to add this test case. pw-bot: cr