From mboxrd@z Thu Jan 1 00:00:00 1970 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 6C594C3DA6F for ; Fri, 25 Aug 2023 16:22:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1343957AbjHYQVv (ORCPT ); Fri, 25 Aug 2023 12:21:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:56648 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1343952AbjHYQVX (ORCPT ); Fri, 25 Aug 2023 12:21:23 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A969C1BD2 for ; Fri, 25 Aug 2023 09:20:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1692980438; 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: in-reply-to:in-reply-to; bh=0ZAYlH739l+imp77wdMvEIGsmJrTe5vS2BECbqXhogw=; b=EO11U5sm0sQvlZfC9wrx3GYWypBhj4F7xljWJrDRDRaBUvwUNEYzxrWHPIPNqhojh6q35/ 6G3WRaU2MFTn/Y/pJDDbhL4tW+U20gjPF/DpInShKil/xzUaeIvITv3wpK7HSowVR9qsAa 8aHuMQ4uiQGLrgSfBtl2A9GjxsPQJFE= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-134-qNskW97aOzyi2U7dJEyALg-1; Fri, 25 Aug 2023 12:20:34 -0400 X-MC-Unique: qNskW97aOzyi2U7dJEyALg-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.rdu2.redhat.com [10.11.54.4]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 1F31485D060; Fri, 25 Aug 2023 16:20:33 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.45.225.136]) by smtp.corp.redhat.com (Postfix) with SMTP id 9ECA52026D68; Fri, 25 Aug 2023 16:20:30 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Fri, 25 Aug 2023 18:19:46 +0200 (CEST) Date: Fri, 25 Aug 2023 18:19:43 +0200 From: Oleg Nesterov To: Andrew Morton , Yonghong Song Cc: "Eric W. Biederman" , Linus Torvalds , Daniel Borkmann , Kui-Feng Lee , Andrii Nakryiko , Martin KaFai Lau , bpf@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH 2/6] bpf: task_group_seq_get_next: cleanup the usage of get/put_task_struct Message-ID: <20230825161943.GA16865@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230825161842.GA16750@redhat.com> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 3.1 on 10.11.54.4 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org get_pid_task() makes no sense, the code does put_task_struct() soon after. Use find_task_by_pid_ns() instead of find_pid_ns + get_pid_task and kill put_task_struct(), this allows to do get_task_struct() only once before return. While at it, kill the unnecessary "if (!pid)" check in the "if (!*tid)" block, this matches the next usage of find_pid_ns() + get_pid_task() in this function. Signed-off-by: Oleg Nesterov Acked-by: Yonghong Song --- kernel/bpf/task_iter.c | 12 ++---------- 1 file changed, 2 insertions(+), 10 deletions(-) diff --git a/kernel/bpf/task_iter.c b/kernel/bpf/task_iter.c index 4d1125108014..1589ec3faded 100644 --- a/kernel/bpf/task_iter.c +++ b/kernel/bpf/task_iter.c @@ -42,9 +42,6 @@ static struct task_struct *task_group_seq_get_next(struct bpf_iter_seq_task_comm if (!*tid) { /* The first time, the iterator calls this function. */ pid = find_pid_ns(common->pid, common->ns); - if (!pid) - return NULL; - task = get_pid_task(pid, PIDTYPE_TGID); if (!task) return NULL; @@ -66,17 +63,12 @@ static struct task_struct *task_group_seq_get_next(struct bpf_iter_seq_task_comm return task; } - pid = find_pid_ns(common->pid_visiting, common->ns); - if (!pid) - return NULL; - - task = get_pid_task(pid, PIDTYPE_PID); + task = find_task_by_pid_ns(common->pid_visiting, common->ns); if (!task) return NULL; retry: next_task = next_thread(task); - put_task_struct(task); saved_tid = *tid; *tid = __task_pid_nr_ns(next_task, PIDTYPE_PID, common->ns); @@ -88,7 +80,6 @@ static struct task_struct *task_group_seq_get_next(struct bpf_iter_seq_task_comm return NULL; } - get_task_struct(next_task); common->pid_visiting = *tid; if (skip_if_dup_files && task->files == task->group_leader->files) { @@ -96,6 +87,7 @@ static struct task_struct *task_group_seq_get_next(struct bpf_iter_seq_task_comm goto retry; } + get_task_struct(next_task); return next_task; } -- 2.25.1.362.g51ebf55