From: Leon Hwang <leon.hwang@linux.dev>
To: Masoud Aghasi <maghasi@disroot.org>, bpf@vger.kernel.org
Cc: andrii@kernel.org, eddyz87@gmail.com, ast@kernel.org,
daniel@iogearbox.net, memxor@gmail.com, martin.lau@linux.dev,
song@kernel.org, yonghong.song@linux.dev, jolsa@kernel.org,
emil@etsalapatis.com, ihor.solodrai@linux.dev
Subject: Re: [PATCH bpf v5 2/3] bpf: Fix incorrect handling of user flags by percpu hash map updates
Date: Wed, 7 Oct 2026 10:43:45 +0800 [thread overview]
Message-ID: <3dd7a2a4-149c-4603-81de-e0247d191e9b@linux.dev> (raw)
In-Reply-To: <20261006084604.780456-3-maghasi@disroot.org>
On 6/10/26 16:46, Masoud Aghasi wrote:
> For BPF_MAP_TYPE_PERCPU_HASH and BPF_MAP_TYPE_LRU_PERCPU_HASH maps,
> htab_map_check_update_flags() and check_flags() are not considering
> the possibility of a combination of (BPF_NOEXIST, BPF_EXIST) flags
> with (BPF_F_CPU, BPF_F_ALL_CPUS) flags. This causes the
> (BPF_NOEXIST, BPF_EXIST) flags to lose their effect in some cases.
>
> For example, when using (BPF_F_CPU | BPF_EXIST) or
> (BPF_F_CPU | BPF_NOEXIST) flag combinations with bpf_map_update_elem()
> on a percpu hash map, the BPF_EXIST flag does not prevent new
> insertions as expected and BPF_NOEXIST flag does not prevent
> modification of existing entries as expected.
>
> This patch fixes the bug by adding proper flag validations and checks.
> Before this patch, htab_map_check_update_flags() rejected
> (BPF_F_ALL_CPUS | BPF_EXIST) and (BPF_F_ALL_CPUS | BPF_NOEXIST) with
> -EINVAL. After the patch those combinations are accepted.
>
> This patch also starts returning -EINVAL for (BPF_EXIST | BPF_NOEXIST),
> with or without BPF_F_CPU, which was previously accepted.
>
> Fixes: c6936161fd55 ("bpf: Add BPF_F_CPU and BPF_F_ALL_CPUS flags support for percpu_hash and lru_percpu_hash maps")
> Signed-off-by: Masoud Aghasi <maghasi@disroot.org>
lgtm,
Acked-by: Leon Hwang <leon.hwang@linux.dev>
> [...]
next prev parent reply other threads:[~2026-10-07 6:42 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-06 8:46 [PATCH bpf v5 0/3] bpf: Fix incorrect handling of user flags by percpu map updates Masoud Aghasi
2026-10-06 8:46 ` [PATCH bpf v5 1/3] bpf: Fix incorrect handling of user flags in bpf_percpu_array_update Masoud Aghasi
2026-10-06 9:16 ` bot+bpf-ci
2026-10-07 2:43 ` Leon Hwang
2026-10-06 8:46 ` [PATCH bpf v5 2/3] bpf: Fix incorrect handling of user flags by percpu hash map updates Masoud Aghasi
2026-10-07 2:43 ` Leon Hwang [this message]
2026-10-06 8:46 ` [PATCH bpf v5 3/3] selftests/bpf: add tests for percpu map flags combination Masoud Aghasi
2026-10-07 2:44 ` Leon Hwang
2026-10-07 17:56 ` Masoud Aghasi
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