From patchwork Thu Jan 4 16:57:44 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yonghong Song X-Patchwork-Id: 13511348 X-Patchwork-Delegate: bpf@iogearbox.net Received: from 66-220-155-178.mail-mxout.facebook.com (66-220-155-178.mail-mxout.facebook.com [66.220.155.178]) (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 6F41125550 for ; Thu, 4 Jan 2024 16:57:57 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=fail smtp.mailfrom=linux.dev Received: by devbig309.ftw3.facebook.com (Postfix, from userid 128203) id F161E2C4DBC49; Thu, 4 Jan 2024 08:57:44 -0800 (PST) From: Yonghong Song To: bpf@vger.kernel.org Cc: Alexei Starovoitov , Andrii Nakryiko , Daniel Borkmann , kernel-team@fb.com, Martin KaFai Lau Subject: [PATCH bpf-next] bpf: Remove unnecessary cpu == 0 check in memalloc Date: Thu, 4 Jan 2024 08:57:44 -0800 Message-Id: <20240104165744.702239-1-yonghong.song@linux.dev> X-Mailer: git-send-email 2.34.1 Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Patchwork-Delegate: bpf@iogearbox.net After merging the patch set [1] to reduce memory usage for bpf_global_percpu_ma, Alexei found a redundant check (cpu == 0) in function bpf_mem_alloc_percpu_unit_init() ([2]). Indeed, the check is unnecessary since c->unit_size will be all NULL or all non-NULL for all cpus before for_each_possible_cpu() loop. Removing the check makes code less confusing. [1] https://lore.kernel.org/all/20231222031729.1287957-1-yonghong.song@linux.dev/ [2] https://lore.kernel.org/all/20231222031745.1289082-1-yonghong.song@linux.dev/ Signed-off-by: Yonghong Song --- kernel/bpf/memalloc.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/kernel/bpf/memalloc.c b/kernel/bpf/memalloc.c index 460c8f38fed6..550f02e2cb13 100644 --- a/kernel/bpf/memalloc.c +++ b/kernel/bpf/memalloc.c @@ -613,7 +613,7 @@ int bpf_mem_alloc_percpu_unit_init(struct bpf_mem_alloc *ma, int size) for_each_possible_cpu(cpu) { cc = per_cpu_ptr(pcc, cpu); c = &cc->cache[i]; - if (cpu == 0 && c->unit_size) + if (c->unit_size) break; c->unit_size = unit_size;