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 B6E9DC00140 for ; Fri, 5 Aug 2022 11:57:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236083AbiHEL5z (ORCPT ); Fri, 5 Aug 2022 07:57:55 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42080 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231347AbiHEL5u (ORCPT ); Fri, 5 Aug 2022 07:57:50 -0400 Received: from mail-ed1-x52b.google.com (mail-ed1-x52b.google.com [IPv6:2a00:1450:4864:20::52b]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B65CF76470 for ; Fri, 5 Aug 2022 04:57:48 -0700 (PDT) Received: by mail-ed1-x52b.google.com with SMTP id x21so3109220edd.3 for ; Fri, 05 Aug 2022 04:57:48 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=colorfullife-com.20210112.gappssmtp.com; s=20210112; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:from:to:cc; bh=9IFcrRZX/CnV4UIXqlxp6Mdb1PIceUrFZLWlYBsRj8o=; b=bTy+O1/anUql+Hc31tuF6+5KPrD6TJMZRBYrkS/MOA9/wBX+81dCSgYJMu2WSOiTna d+8XCnNTXtxNaOmYvCIG5YnzXl1uLqDJTsSgR+jxTpzGNkmvwDLkrsYDLZ5NtpVgWcHv GPr1ibEwLfnfT3hxMSmTU6TouSRjE92sSr7VUZ5YM9QC0MFptzJ5YvZjUsBlpIs7roL4 hit7DT5J0FcWTRhhEr/7lzDoTpj13h1rBfkv4EvGQ7QETsLuW73l1uyKqDVrqQxmVskn JW5Dbmzb9VDRmh+GO2ekcu2um3H5IySy9DCfi+wbHzmItpopW5JPOYWitblR+ZczbndK C3Jg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:message-id:date:subject:cc :to:from:x-gm-message-state:from:to:cc; bh=9IFcrRZX/CnV4UIXqlxp6Mdb1PIceUrFZLWlYBsRj8o=; b=qqhPMWyYn2p25Qi6fJEDAgDi2mAYSy164jQ/1dtFMqpUrknmILgTQm8U/tKxvgd9Lx jenj5y+Dkz6zy9d6YZAVdXaOVj2GSnFxhkApSuxSexP5qntNvad36Rbw1UtMToCtFpjS q+khVtOH9shiv/RniOrS+Oqbq0EUMiY2+euRWj9XSA3SOsphqGe9pVA+HUqauVSoDvXz oo9VLx6ypWyGx5ksKhm2Kn8U+HhSyZR1KYPNoxIaEkJ0oe0fE4TEyYVupJMdvdXd0pEG yebnulnP+iV7+1zVvwdRMcG1SH6S+yd5M5W/eo1kb5S0Qupusn469ex00WzK3nhNydSu Hsbg== X-Gm-Message-State: ACgBeo0PSkZ75XACoxhUsj/ACXMBUW1Z79EaoI05iMHPOGZZjQC29cVR 1YSffwYRkfPiYy9OzzmoVBrLqFjfDlVkJQ== X-Google-Smtp-Source: AA6agR5QOMzpP+mAS3PyycCHlndfEHgm/KzScHlT1ys5+53/fXBo1JTgNdgTNbjFD8uFYoGMmJJ3AQ== X-Received: by 2002:aa7:c14e:0:b0:43d:7bad:b53e with SMTP id r14-20020aa7c14e000000b0043d7badb53emr6219629edp.353.1659700667002; Fri, 05 Aug 2022 04:57:47 -0700 (PDT) Received: from localhost.localdomain (p200300d99703c2003e69dd231e074304.dip0.t-ipconnect.de. [2003:d9:9703:c200:3e69:dd23:1e07:4304]) by smtp.googlemail.com with ESMTPSA id dy9-20020a05640231e900b0043bc19efc15sm1977921edb.28.2022.08.05.04.57.46 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 05 Aug 2022 04:57:46 -0700 (PDT) From: Manfred Spraul To: LKML , Andrew Morton Cc: "Eric W . Biederman" , Davidlohr Bueso , 1vier1@web.de, Manfred Spraul , Waiman Long Subject: [PATCH] ipc/util.c: Cleanup and improve sysvipc_find_ipc(), V3 Date: Fri, 5 Aug 2022 13:57:33 +0200 Message-Id: <20220805115733.104763-1-manfred@colorfullife.com> X-Mailer: git-send-email 2.37.1 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org sysvipc_find_ipc() can be simplified further: - It uses a for() loop to locate the next entry in the idr. This can be replaced with idr_get_next(). - It receives two parameters (pos - which is actually an idr index and not a position, and new_pos, which is really a position). One parameter is sufficient. Link: https://lore.kernel.org/all/20210903052020.3265-3-manfred@colorfullife.com/ Acked-by: Waiman Long Signed-off-by: Manfred Spraul --- Resending the patch, it seems it was stuck: - typo noticed by Waiman corrected. - rediffed - retested @Andrew: Could you add it it linux-next/mm? It is in my outbox for > 6 months now, and using a for() loop instead of idr_get_next() is just wrong. And the variable naming should be cleaned up as well (idx -> index, without sequence number. id -> user space id, with sequence number. The current function doesn't follow that) ipc/util.c | 53 ++++++++++++++++++++++++++++++++--------------------- 1 file changed, 32 insertions(+), 21 deletions(-) diff --git a/ipc/util.c b/ipc/util.c index a2208d0f26b2..05cb9de66735 100644 --- a/ipc/util.c +++ b/ipc/util.c @@ -782,28 +782,37 @@ struct pid_namespace *ipc_seq_pid_ns(struct seq_file *s) return iter->pid_ns; } -/* - * This routine locks the ipc structure found at least at position pos. +/** + * sysvipc_find_ipc - Find and lock the ipc structure based on seq pos + * @ids: ipc identifier set + * @pos: expected position + * + * The function finds an ipc structure, based on the sequence file + * position @pos. If there is no ipc structure at position @pos, then + * the successor is selected. + * If a structure is found, then it is locked (both rcu_read_lock() and + * ipc_lock_object()) and @pos is set to the position needed to locate + * the found ipc structure. + * If nothing is found (i.e. EOF), @pos is not modified. + * + * The function returns the found ipc structure, or NULL at EOF. */ -static struct kern_ipc_perm *sysvipc_find_ipc(struct ipc_ids *ids, loff_t pos, - loff_t *new_pos) +static struct kern_ipc_perm *sysvipc_find_ipc(struct ipc_ids *ids, loff_t *pos) { - struct kern_ipc_perm *ipc = NULL; - int max_idx = ipc_get_maxidx(ids); + int tmpidx; + struct kern_ipc_perm *ipc; - if (max_idx == -1 || pos > max_idx) - goto out; + /* convert from position to idr index -> "-1" */ + tmpidx = *pos - 1; - for (; pos <= max_idx; pos++) { - ipc = idr_find(&ids->ipcs_idr, pos); - if (ipc != NULL) { - rcu_read_lock(); - ipc_lock_object(ipc); - break; - } + ipc = idr_get_next(&ids->ipcs_idr, &tmpidx); + if (ipc != NULL) { + rcu_read_lock(); + ipc_lock_object(ipc); + + /* convert from idr index to position -> "+1" */ + *pos = tmpidx + 1; } -out: - *new_pos = pos + 1; return ipc; } @@ -817,11 +826,13 @@ static void *sysvipc_proc_next(struct seq_file *s, void *it, loff_t *pos) if (ipc && ipc != SEQ_START_TOKEN) ipc_unlock(ipc); - return sysvipc_find_ipc(&iter->ns->ids[iface->ids], *pos, pos); + /* Next -> search for *pos+1 */ + (*pos)++; + return sysvipc_find_ipc(&iter->ns->ids[iface->ids], pos); } /* - * File positions: pos 0 -> header, pos n -> ipc id = n - 1. + * File positions: pos 0 -> header, pos n -> ipc idx = n - 1. * SeqFile iterator: iterator value locked ipc pointer or SEQ_TOKEN_START. */ static void *sysvipc_proc_start(struct seq_file *s, loff_t *pos) @@ -846,8 +857,8 @@ static void *sysvipc_proc_start(struct seq_file *s, loff_t *pos) if (*pos == 0) return SEQ_START_TOKEN; - /* Find the (pos-1)th ipc */ - return sysvipc_find_ipc(ids, *pos - 1, pos); + /* Otherwise return the correct ipc structure */ + return sysvipc_find_ipc(ids, pos); } static void sysvipc_proc_stop(struct seq_file *s, void *it) -- 2.37.1