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 X-Spam-Level: X-Spam-Status: No, score=-19.3 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B0F14C433E0 for ; Mon, 8 Feb 2021 15:08:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6EE4464EE5 for ; Mon, 8 Feb 2021 15:08:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231518AbhBHPIQ (ORCPT ); Mon, 8 Feb 2021 10:08:16 -0500 Received: from mail.kernel.org ([198.145.29.99]:52046 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232292AbhBHPGR (ORCPT ); Mon, 8 Feb 2021 10:06:17 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id DB18064EDC; Mon, 8 Feb 2021 15:04:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1612796686; bh=fW+Erbrqny4By5bngQoLTZqJRRW8VgagnPNDxzSofz4=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=c+MUlj1UXV5r20o7BLBRcSjRIPMgjTZesPcRMlAC0jXMY6hu9tCEgz4bQ718AvHGQ KW4N/Io0NdYHrQNtvlrBR5tHResRIAItOYpjZ4bAkWNwsAJBIW373u8jIS8g/k/B/E 7hPFt1RAbafVxY7WJXQ5IKQgr8IePKl0cPMPWdq0= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Greg Kroah-Hartman , Thomas Gleixner , "Peter Zijlstra (Intel)" , Lee Jones Subject: [PATCH 4.9 09/43] futex: Provide and use pi_state_update_owner() Date: Mon, 8 Feb 2021 16:00:35 +0100 Message-Id: <20210208145806.674855687@linuxfoundation.org> X-Mailer: git-send-email 2.30.0 In-Reply-To: <20210208145806.281758651@linuxfoundation.org> References: <20210208145806.281758651@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Thomas Gleixner [ Upstream commit c5cade200ab9a2a3be9e7f32a752c8d86b502ec7 ] Updating pi_state::owner is done at several places with the same code. Provide a function for it and use that at the obvious places. This is also a preparation for a bug fix to avoid yet another copy of the same code or alternatively introducing a completely unpenetratable mess of gotos. Originally-by: Peter Zijlstra Signed-off-by: Thomas Gleixner Acked-by: Peter Zijlstra (Intel) Cc: stable@vger.kernel.org Signed-off-by: Lee Jones Signed-off-by: Greg Kroah-Hartman --- kernel/futex.c | 64 +++++++++++++++++++++++++++++---------------------------- 1 file changed, 33 insertions(+), 31 deletions(-) --- a/kernel/futex.c +++ b/kernel/futex.c @@ -837,6 +837,29 @@ static struct futex_pi_state * alloc_pi_ return pi_state; } +static void pi_state_update_owner(struct futex_pi_state *pi_state, + struct task_struct *new_owner) +{ + struct task_struct *old_owner = pi_state->owner; + + lockdep_assert_held(&pi_state->pi_mutex.wait_lock); + + if (old_owner) { + raw_spin_lock(&old_owner->pi_lock); + WARN_ON(list_empty(&pi_state->list)); + list_del_init(&pi_state->list); + raw_spin_unlock(&old_owner->pi_lock); + } + + if (new_owner) { + raw_spin_lock(&new_owner->pi_lock); + WARN_ON(!list_empty(&pi_state->list)); + list_add(&pi_state->list, &new_owner->pi_state_list); + pi_state->owner = new_owner; + raw_spin_unlock(&new_owner->pi_lock); + } +} + /* * Drops a reference to the pi_state object and frees or caches it * when the last reference is gone. @@ -1432,26 +1455,16 @@ static int wake_futex_pi(u32 __user *uad else ret = -EINVAL; } - if (ret) { - raw_spin_unlock_irq(&pi_state->pi_mutex.wait_lock); - return ret; - } - - raw_spin_lock(&pi_state->owner->pi_lock); - WARN_ON(list_empty(&pi_state->list)); - list_del_init(&pi_state->list); - raw_spin_unlock(&pi_state->owner->pi_lock); - raw_spin_lock(&new_owner->pi_lock); - WARN_ON(!list_empty(&pi_state->list)); - list_add(&pi_state->list, &new_owner->pi_state_list); - pi_state->owner = new_owner; - raw_spin_unlock(&new_owner->pi_lock); - - /* - * We've updated the uservalue, this unlock cannot fail. - */ - deboost = __rt_mutex_futex_unlock(&pi_state->pi_mutex, &wake_q); + if (!ret) { + /* + * This is a point of no return; once we modified the uval + * there is no going back and subsequent operations must + * not fail. + */ + pi_state_update_owner(pi_state, new_owner); + deboost = __rt_mutex_futex_unlock(&pi_state->pi_mutex, &wake_q); + } raw_spin_unlock_irq(&pi_state->pi_mutex.wait_lock); spin_unlock(&hb->lock); @@ -2353,19 +2366,8 @@ retry: * We fixed up user space. Now we need to fix the pi_state * itself. */ - if (pi_state->owner != NULL) { - raw_spin_lock_irq(&pi_state->owner->pi_lock); - WARN_ON(list_empty(&pi_state->list)); - list_del_init(&pi_state->list); - raw_spin_unlock_irq(&pi_state->owner->pi_lock); - } - - pi_state->owner = newowner; + pi_state_update_owner(pi_state, newowner); - raw_spin_lock_irq(&newowner->pi_lock); - WARN_ON(!list_empty(&pi_state->list)); - list_add(&pi_state->list, &newowner->pi_state_list); - raw_spin_unlock_irq(&newowner->pi_lock); return 0; /*