From patchwork Tue Nov 14 16:32:34 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Oleg Nesterov X-Patchwork-Id: 165016 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a05:6358:a59:b0:164:83eb:24d7 with SMTP id 25csp2046212rwb; Tue, 14 Nov 2023 08:34:14 -0800 (PST) X-Google-Smtp-Source: AGHT+IH+GuFo/XMH8WPsYM3ZEp5+1gY1uHfyfpR7zp00UHZxLn0tLB6GRHd6F31MBzeBT2ZvRAfA X-Received: by 2002:a17:902:bcc9:b0:1cc:49e7:ee1b with SMTP id o9-20020a170902bcc900b001cc49e7ee1bmr2963841pls.58.1699979654164; Tue, 14 Nov 2023 08:34:14 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1699979654; cv=none; d=google.com; s=arc-20160816; b=lvW7VKFSFlqy+A0ud3+BgOUtiPTrLlKx4RaEsXJ2JYAO/gRZ5zKWkmpfc4rujde8Jv yFltCI6mTk355YL67HYd6MPAXQD9rlDivu7u5UdCuV+kkNdArpMUC4OBI6FXFUSHMDuA rKMZ5gcNZaTsCD0CYwt3P1TPRwJv4kPFpoBh6UD7vw4uHIEfOj3Quamfc9G/oZTKN6kt gA3bWg7Ubq8MzWl/10UZKDMwjRnfrz6flqFD6oNoPfIu8b57+3PB+HvkpTAICEVqf7Jl J6+ZTi0E3bZg6+AOQQVMYprIWlMweVWwr8FTEgcPozHkZoI6gUvg/rf6u7FFoWvffh/9 hU/w== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:user-agent:in-reply-to:content-disposition :mime-version:message-id:subject:cc:to:from:date:dkim-signature; bh=BkORamFmgjQm3rT3wXmKJVf5l2MYL+TWgwU+R0JxK1c=; fh=pTGUKWZxncu7pMozd936arYcX4w7ULKvTVsDVCv3mqw=; b=EVW3QjNI06A1B+0uGYF3havaqtHOu52rlehoCBmEmpcSXqI6SBDkGBQIqHd9NPbH4T 4I5eQgNLtSpw1tDTaptLZ9gbIR+J+JlNEuFXuymQfIEI86XIpu72JSUN1rCnfK8gPgwv IgJk4Mn8mYwoXznv638gEjH0cU6CTQSDQqjzpzDYifS5V1HKcxjOKdgm8wQzwrr/UM/f St/LZN0TMBvvhlzSB3RAwM3XC1eEIx++DXZB4lWGHx76FdA8KcF+nnEWnVWdZCMydl6G Weq46vIEtV46bzFcBv9ld2gCn9KEobzZgJ9Rp7by99NopQFB6vQLeeZD5P93QRnXXkMb 3AwA== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@redhat.com header.s=mimecast20190719 header.b=O9xJJH+c; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:3 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: from lipwig.vger.email (lipwig.vger.email. [2620:137:e000::3:3]) by mx.google.com with ESMTPS id m6-20020a170902f64600b001c7615a8e09si8671084plg.593.2023.11.14.08.34.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 14 Nov 2023 08:34:14 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:3 as permitted sender) client-ip=2620:137:e000::3:3; Authentication-Results: mx.google.com; dkim=pass header.i=@redhat.com header.s=mimecast20190719 header.b=O9xJJH+c; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:3 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: from out1.vger.email (depot.vger.email [IPv6:2620:137:e000::3:0]) by lipwig.vger.email (Postfix) with ESMTP id 827A9802F946; Tue, 14 Nov 2023 08:34:11 -0800 (PST) X-Virus-Status: Clean X-Virus-Scanned: clamav-milter 0.103.11 at lipwig.vger.email Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229822AbjKNQdw (ORCPT + 29 others); Tue, 14 Nov 2023 11:33:52 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47308 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232101AbjKNQdv (ORCPT ); Tue, 14 Nov 2023 11:33:51 -0500 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 08D33112 for ; Tue, 14 Nov 2023 08:33:47 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1699979627; 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=BkORamFmgjQm3rT3wXmKJVf5l2MYL+TWgwU+R0JxK1c=; b=O9xJJH+cmHlfqT7imG4tOUTDYcg16yAZc2RMofJvynu1mumE6/NYEyh1g3gXCbQ+VgmD9d U3wNJUEs8TJhSDiFp5NatW0alpEMY3tugI8n8wZUQhBbmby2AML8mDxofV/aq+xEkjCWVs YrbkSI3nT6LY9JdGEHUvZ7PEVtD0QqM= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-520-yLGSOGLEP8ui6el_IihhxQ-1; Tue, 14 Nov 2023 11:33:41 -0500 X-MC-Unique: yLGSOGLEP8ui6el_IihhxQ-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 49EE5811E8F; Tue, 14 Nov 2023 16:33:41 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.45.225.253]) by smtp.corp.redhat.com (Postfix) with SMTP id CA84B5028; Tue, 14 Nov 2023 16:33:39 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Tue, 14 Nov 2023 17:32:36 +0100 (CET) Date: Tue, 14 Nov 2023 17:32:34 +0100 From: Oleg Nesterov To: Alexei Starovoitov , Yonghong Song Cc: Chuyi Zhou , Daniel Borkmann , Kui-Feng Lee , linux-kernel@vger.kernel.org, bpf@vger.kernel.org Subject: [PATCH 1/3] bpf: task_group_seq_get_next: use __next_thread() rather than next_thread() Message-ID: <20231114163234.GA890@redhat.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20231114163211.GA874@redhat.com> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.5 X-Spam-Status: No, score=-0.9 required=5.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,T_SCC_BODY_TEXT_LINE autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lipwig.vger.email Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-Greylist: Sender passed SPF test, not delayed by milter-greylist-4.6.4 (lipwig.vger.email [0.0.0.0]); Tue, 14 Nov 2023 08:34:11 -0800 (PST) X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1782557865972483967 X-GMAIL-MSGID: 1782557865972483967 Lockless use of next_thread() should be avoided, kernel/bpf/task_iter.c is the last user and the usage is wrong. task_group_seq_get_next() can return the group leader twice if it races with mt-thread exec which changes the group->leader's pid. Change the main loop to use __next_thread(), kill "next_tid == common->pid" check. __next_thread() can't loop forever, we can also change this code to retry if next_tid == 0. Signed-off-by: Oleg Nesterov Acked-by: Yonghong Song --- kernel/bpf/task_iter.c | 12 +++++------- 1 file changed, 5 insertions(+), 7 deletions(-) diff --git a/kernel/bpf/task_iter.c b/kernel/bpf/task_iter.c index 26082b97894d..51ae15e2b290 100644 --- a/kernel/bpf/task_iter.c +++ b/kernel/bpf/task_iter.c @@ -70,15 +70,13 @@ static struct task_struct *task_group_seq_get_next(struct bpf_iter_seq_task_comm return NULL; retry: - task = next_thread(task); + task = __next_thread(task); + if (!task) + return NULL; next_tid = __task_pid_nr_ns(task, PIDTYPE_PID, common->ns); - if (!next_tid || next_tid == common->pid) { - /* Run out of tasks of a process. The tasks of a - * thread_group are linked as circular linked list. - */ - return NULL; - } + if (!next_tid) + goto retry; if (skip_if_dup_files && task->files == task->group_leader->files) goto retry; From patchwork Tue Nov 14 16:32:37 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Oleg Nesterov X-Patchwork-Id: 165015 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a05:6358:a59:b0:164:83eb:24d7 with SMTP id 25csp2046190rwb; Tue, 14 Nov 2023 08:34:13 -0800 (PST) X-Google-Smtp-Source: AGHT+IEIcMUJoefDSixJ9PKqYwNn9icJt++V2CMgBUAB61c6Zkdys7dONuAG8ONXgQ8jKtISGmHL X-Received: by 2002:a17:90b:1d87:b0:280:8778:c4ab with SMTP id pf7-20020a17090b1d8700b002808778c4abmr7544163pjb.24.1699979652753; Tue, 14 Nov 2023 08:34:12 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1699979652; cv=none; d=google.com; s=arc-20160816; b=BGqSoost8IY550wmG9GknUXm5TvzgFAExxtNWt0sd0woFaylvI/glQoc7x6sLzJKiI OnyO4gzFjeM7xn6mDKndvtT05aUj1iM2tbc5IWwmTfsS38azC33AfaFc3ofSGwV2M88s CfVrFM8oVgIlKVd4sQViWWJJC1dt6QR0w9Mkk2urjOK6hxy56NUgAnIrFVSz7GgKqNCw IGcJknoi2gh2iVY0q6BzRYYsCxuUe0Yvm9j7HZpRh3ugMEO7v4DQMwRv5e9GhPoaXVqD aAps0wKJH581jp5FuOqhmnZHiy9vKt7gcKpstDl4rVC6EgZ9bwuQ7tt2WZ+ez/v7CkGI Hysw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:user-agent:in-reply-to:content-disposition :mime-version:message-id:subject:cc:to:from:date:dkim-signature; bh=2Mg3UCFMr1SH7PUf+Sl5YMeVrQDgFkP/RxqlBy+YY5Y=; fh=pTGUKWZxncu7pMozd936arYcX4w7ULKvTVsDVCv3mqw=; b=YMnusPq8OsRcoKnmN30tkhWd4a7Jtux9FQhiSkEWtZFLsl+PtaiPZ0f54jZAabt7sG MR0B0JkSZn/hNJhhXKZ8kXTThWjy7MzffkLgqDR1prpHDfstM0Aw2vP6o/2PIwo7D4zT +X3GexYwp/XtNhkvwOcam9XiSMe/zgoMn32SKVLGaq07ex+ObG9/Ln0pTkbID6vy/tf9 x+LC5CE82qIWnP1fQRsiH5KmvB9S+stXZLMe5ytj+84z/GrtOLPlpq040ZiT/BzzPHbo uUpi9QigjHW/7+ejlPZwkQbt5N3EH0a+VrISUPBO+9scWuqKBo43HTTA55jW5BGWXo0a YZ1A== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@redhat.com header.s=mimecast20190719 header.b=KMLxl460; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:3 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: from lipwig.vger.email (lipwig.vger.email. [2620:137:e000::3:3]) by mx.google.com with ESMTPS id t12-20020a17090a448c00b0027b15e572c2si12610350pjg.21.2023.11.14.08.34.12 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 14 Nov 2023 08:34:12 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:3 as permitted sender) client-ip=2620:137:e000::3:3; Authentication-Results: mx.google.com; dkim=pass header.i=@redhat.com header.s=mimecast20190719 header.b=KMLxl460; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:3 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: from out1.vger.email (depot.vger.email [IPv6:2620:137:e000::3:0]) by lipwig.vger.email (Postfix) with ESMTP id F1117802F94A; Tue, 14 Nov 2023 08:34:09 -0800 (PST) X-Virus-Status: Clean X-Virus-Scanned: clamav-milter 0.103.11 at lipwig.vger.email Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233714AbjKNQdy (ORCPT + 29 others); Tue, 14 Nov 2023 11:33:54 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44074 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233721AbjKNQdw (ORCPT ); Tue, 14 Nov 2023 11:33:52 -0500 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 B48AD182 for ; Tue, 14 Nov 2023 08:33:49 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1699979629; 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=2Mg3UCFMr1SH7PUf+Sl5YMeVrQDgFkP/RxqlBy+YY5Y=; b=KMLxl460hnji69qZ7WIoNEWpWS44Ei8hH6CpZZIXFIFrsOWvyAPmp4FiJqmqZV1c39vd4z iYkgXySYtQlgacst/95ZWpbJTcIHrFLUEWr4kiWeQOSO8zp/JQQbtTwiYGf2b/C4u0mHPN mfs2WeyZFheM3mzTjEkHT2rGLyvcO+8= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-140-areqUpPuN-OXmCaWVP_OIg-1; Tue, 14 Nov 2023 11:33:45 -0500 X-MC-Unique: areqUpPuN-OXmCaWVP_OIg-1 Received: from smtp.corp.redhat.com (int-mx10.intmail.prod.int.rdu2.redhat.com [10.11.54.10]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 24813811E93; Tue, 14 Nov 2023 16:33:44 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.45.225.253]) by smtp.corp.redhat.com (Postfix) with SMTP id 46294493113; Tue, 14 Nov 2023 16:33:42 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Tue, 14 Nov 2023 17:32:39 +0100 (CET) Date: Tue, 14 Nov 2023 17:32:37 +0100 From: Oleg Nesterov To: Alexei Starovoitov , Yonghong Song Cc: Chuyi Zhou , Daniel Borkmann , Kui-Feng Lee , linux-kernel@vger.kernel.org, bpf@vger.kernel.org Subject: [PATCH 2/3] bpf: bpf_iter_task_next: use __next_thread() rather than next_thread() Message-ID: <20231114163237.GA897@redhat.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20231114163211.GA874@redhat.com> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.10 X-Spam-Status: No, score=-0.9 required=5.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,T_SCC_BODY_TEXT_LINE autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lipwig.vger.email Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-Greylist: Sender passed SPF test, not delayed by milter-greylist-4.6.4 (lipwig.vger.email [0.0.0.0]); Tue, 14 Nov 2023 08:34:10 -0800 (PST) X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1782557864327126508 X-GMAIL-MSGID: 1782557864327126508 Lockless use of next_thread() should be avoided, kernel/bpf/task_iter.c is the last user and the usage is wrong. bpf_iter_task_next() can loop forever, "kit->pos == kit->task" can never happen if kit->pos execs. Change this code to use __next_thread(). With or without this change the usage of kit->pos/task and next_task() doesn't look nice, see the next patch. Signed-off-by: Oleg Nesterov Acked-by: Yonghong Song --- kernel/bpf/task_iter.c | 9 ++++----- 1 file changed, 4 insertions(+), 5 deletions(-) diff --git a/kernel/bpf/task_iter.c b/kernel/bpf/task_iter.c index 51ae15e2b290..d42e08d0d0b7 100644 --- a/kernel/bpf/task_iter.c +++ b/kernel/bpf/task_iter.c @@ -1015,12 +1015,11 @@ __bpf_kfunc struct task_struct *bpf_iter_task_next(struct bpf_iter_task *it) if (flags == BPF_TASK_ITER_ALL_PROCS) goto get_next_task; - kit->pos = next_thread(kit->pos); - if (kit->pos == kit->task) { - if (flags == BPF_TASK_ITER_PROC_THREADS) { - kit->pos = NULL; + kit->pos = __next_thread(kit->pos); + if (!kit->pos) { + if (flags == BPF_TASK_ITER_PROC_THREADS) return pos; - } + kit->pos = kit->task; } else return pos; From patchwork Tue Nov 14 16:32:39 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Oleg Nesterov X-Patchwork-Id: 165017 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a05:6358:a59:b0:164:83eb:24d7 with SMTP id 25csp2046270rwb; Tue, 14 Nov 2023 08:34:18 -0800 (PST) X-Google-Smtp-Source: AGHT+IH1jHWqSogEtw2UutRVSBwKHm24wxeGPChpAC0gMrQ4zDUmBQ7IoePXa8lZ3GuJQ6vu1Cvj X-Received: by 2002:a05:6a00:4599:b0:6c3:6148:570f with SMTP id it25-20020a056a00459900b006c36148570fmr10477243pfb.33.1699979658459; Tue, 14 Nov 2023 08:34:18 -0800 (PST) ARC-Seal: i=1; a=rsa-sha256; t=1699979658; cv=none; d=google.com; s=arc-20160816; b=TKQHlLNLczUbKBoMBaoe7CN597doidldZRwLkOsZeH5JNKbGqfG8MahiM/3vfMQnTx XEYgPr95gHAwp0RMVB21Js5MqrOpnL2Ow1jnou2qvD6446pI0kHFFx7bj7+gQzzEnFgm E2+/GUhhngzFAd7blG4/FFCnTfBCASFr/gpMl8w7tYYdnS/7yBr8OsEpT51k/D81lGTP Zov7CTzf4rmJtUHpZ9VipI5vhw+0qEPr5j3a5G61DcJpQoUPq/wM71ocU35GwBJdcBld Ajdpw+Qi1RNCAecAWEtxRfQ+Fm6o3f0rptcMF/Ys49SFCmxBQB7OQaAWU1j3o021KRcW E/xw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:user-agent:in-reply-to:content-disposition :mime-version:message-id:subject:cc:to:from:date:dkim-signature; bh=u12QSukl/sf9yDwpJ5WMUElypfqqvvHxept5As9gCMA=; fh=pTGUKWZxncu7pMozd936arYcX4w7ULKvTVsDVCv3mqw=; b=oCBoha7kSi8h0cGn+omk6wzaC58QqWzsQsXfofP13/YbFAqXWFn9JV8i6vTZ22JhDc xQakfPGB0WH9SwNxBj6Sz0gE6Y8EICwxExLVIMmvEpj+AnDvDJLjRCBqnpce62E2Kh08 RIokPA4OV0db+YGUJj20Oh38+XThPioplNrF3sFciH7xGIIPDC5WGzKj6RV7v14qmWJz kVBDVZATUqxFBC0mPlYsaMEmWVp+zu9bfsc3taL09MTczwkvX/8/bUIu1NO9/irmy0dS l1AiuAPozPIqXalhh7lB4qeCTmRX35qCil0PhlXOuJFkTd6EZz42HOfkSgSKI7k9ilgA VQmg== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@redhat.com header.s=mimecast20190719 header.b=BBIquyvc; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:3 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: from lipwig.vger.email (lipwig.vger.email. [2620:137:e000::3:3]) by mx.google.com with ESMTPS id t184-20020a6381c1000000b005b999968b85si8013534pgd.666.2023.11.14.08.34.17 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 14 Nov 2023 08:34:18 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:3 as permitted sender) client-ip=2620:137:e000::3:3; Authentication-Results: mx.google.com; dkim=pass header.i=@redhat.com header.s=mimecast20190719 header.b=BBIquyvc; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::3:3 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=redhat.com Received: from out1.vger.email (depot.vger.email [IPv6:2620:137:e000::3:0]) by lipwig.vger.email (Postfix) with ESMTP id 4808D802F947; Tue, 14 Nov 2023 08:34:16 -0800 (PST) X-Virus-Status: Clean X-Virus-Scanned: clamav-milter 0.103.11 at lipwig.vger.email Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233745AbjKNQd7 (ORCPT + 29 others); Tue, 14 Nov 2023 11:33:59 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:44112 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233728AbjKNQdz (ORCPT ); Tue, 14 Nov 2023 11:33:55 -0500 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 D0B2811B for ; Tue, 14 Nov 2023 08:33:52 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1699979632; 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=u12QSukl/sf9yDwpJ5WMUElypfqqvvHxept5As9gCMA=; b=BBIquyvchw81uNuNUN7nHQvhMQRSfJbzkzoFTvAAX9o3is0eIngo7Xro6C81cH1UnPqVeS mCQ47sFZRGZVMxfQF5fh9bXQjHGhoNlMUBpMnPBSBXG5scXoOKf8fTu0Rtlyqi0r5ynATD vP2qsg9MONpO5XP8Bsuj8vMm6+jWVvQ= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-528-snAvf6GpMGSW2NMVnMYu4w-1; Tue, 14 Nov 2023 11:33:47 -0500 X-MC-Unique: snAvf6GpMGSW2NMVnMYu4w-1 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.rdu2.redhat.com [10.11.54.4]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 3CF7B85C6EA; Tue, 14 Nov 2023 16:33:47 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.45.225.253]) by smtp.corp.redhat.com (Postfix) with SMTP id 3EC072026D66; Tue, 14 Nov 2023 16:33:45 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Tue, 14 Nov 2023 17:32:42 +0100 (CET) Date: Tue, 14 Nov 2023 17:32:39 +0100 From: Oleg Nesterov To: Alexei Starovoitov , Yonghong Song Cc: Chuyi Zhou , Daniel Borkmann , Kui-Feng Lee , linux-kernel@vger.kernel.org, bpf@vger.kernel.org Subject: [PATCH 3/3] bpf: bpf_iter_task_next: use next_task(kit->task) rather than next_task(kit->pos) Message-ID: <20231114163239.GA903@redhat.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20231114163211.GA874@redhat.com> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.4 X-Spam-Status: No, score=-0.9 required=5.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,T_SCC_BODY_TEXT_LINE autolearn=unavailable autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lipwig.vger.email Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-Greylist: Sender passed SPF test, not delayed by milter-greylist-4.6.4 (lipwig.vger.email [0.0.0.0]); Tue, 14 Nov 2023 08:34:16 -0800 (PST) X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1782557870357438324 X-GMAIL-MSGID: 1782557870357438324 This looks more clear and simplifies the code. While at it, remove the unnecessary initialization of pos/task at the start of bpf_iter_task_new(). Note that we can even kill kit->task, we can just use pos->group_leader, but I don't understand the BUILD_BUG_ON() checks in bpf_iter_task_new(). Signed-off-by: Oleg Nesterov Acked-by: Yonghong Song --- kernel/bpf/task_iter.c | 14 +++++--------- 1 file changed, 5 insertions(+), 9 deletions(-) diff --git a/kernel/bpf/task_iter.c b/kernel/bpf/task_iter.c index d42e08d0d0b7..e5c3500443c6 100644 --- a/kernel/bpf/task_iter.c +++ b/kernel/bpf/task_iter.c @@ -978,7 +978,6 @@ __bpf_kfunc int bpf_iter_task_new(struct bpf_iter_task *it, BUILD_BUG_ON(__alignof__(struct bpf_iter_task_kern) != __alignof__(struct bpf_iter_task)); - kit->task = kit->pos = NULL; switch (flags) { case BPF_TASK_ITER_ALL_THREADS: case BPF_TASK_ITER_ALL_PROCS: @@ -1016,18 +1015,15 @@ __bpf_kfunc struct task_struct *bpf_iter_task_next(struct bpf_iter_task *it) goto get_next_task; kit->pos = __next_thread(kit->pos); - if (!kit->pos) { - if (flags == BPF_TASK_ITER_PROC_THREADS) - return pos; - kit->pos = kit->task; - } else + if (kit->pos || flags == BPF_TASK_ITER_PROC_THREADS) return pos; get_next_task: - kit->pos = next_task(kit->pos); - kit->task = kit->pos; - if (kit->pos == &init_task) + kit->task = next_task(kit->task); + if (kit->task == &init_task) kit->pos = NULL; + else + kit->pos = kit->task; return pos; }