From patchwork Tue Jan 26 20:04:58 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: thermal-bot for Julien Panis X-Patchwork-Id: 372362 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=-20.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, DKIM_VALID_AU, HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, MENTIONS_GIT_HOSTING, SPF_HELO_NONE, SPF_PASS, URIBL_BLOCKED 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 BBE6FC43219 for ; Tue, 26 Jan 2021 22:19:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 96850206B5 for ; Tue, 26 Jan 2021 22:19:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727028AbhAZWAk (ORCPT ); Tue, 26 Jan 2021 17:00:40 -0500 Received: from Galois.linutronix.de ([193.142.43.55]:51524 "EHLO galois.linutronix.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2391612AbhAZUFn (ORCPT ); Tue, 26 Jan 2021 15:05:43 -0500 Date: Tue, 26 Jan 2021 20:04:58 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1611691500; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=5i1bS5xaTAzafC9EVeTJB6D98YZjamO0Dtekf7yIRFU=; b=4lFnXwcFbbmfP0QlWfwl6Bew2XQXZWx8Q86ekIHSJcYcHbK/ZRPEPL+uRkkFcPnzQ5ohxr rchtOgFl8UVuSQJRF6fh35WiJm7GobXahni23suPHyfgAkIJDN5Bbj83ZKRMIVN9olGWkQ rByKPEmgz+XzbrSC/mDuPO9bFHgJW76/WPKwUqZ9qQdYUu8/8VgDFyUYJoQ6EcoWAsQ/PX 4JWzWdfzOX0k+ApDSiFFTozKePx/bDDyTFzXPG4LSzjHWWaGWyYBDnqMCGyo+Fqd7C3NfG w0UecyJY8v/78tpn/8MLR11sUQZDhUAQ4lxvvXP19EXeBe+z/Q2Turovft4/SA== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1611691501; h=from:from:sender:sender:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=5i1bS5xaTAzafC9EVeTJB6D98YZjamO0Dtekf7yIRFU=; b=j9n7LRQo5GGA5QbiinsRz1TFJqY2QuzYAxGb7ktwCcHUuLRVzO0zM/hGnYze0yG/wE1Vea GzNuJTyo0ejHIPDA== From: "tip-bot2 for Thomas Gleixner" Sender: tip-bot2@linutronix.de Reply-to: linux-kernel@vger.kernel.org To: linux-tip-commits@vger.kernel.org Subject: [tip: locking/urgent] futex: Provide and use pi_state_update_owner() Cc: Peter Zijlstra , Thomas Gleixner , stable@vger.kernel.org, x86@kernel.org, linux-kernel@vger.kernel.org MIME-Version: 1.0 Message-ID: <161169149846.414.14379352589492636849.tip-bot2@tip-bot2> Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org The following commit has been merged into the locking/urgent branch of tip: Commit-ID: c5cade200ab9a2a3be9e7f32a752c8d86b502ec7 Gitweb: https://git.kernel.org/tip/c5cade200ab9a2a3be9e7f32a752c8d86b502ec7 Author: Thomas Gleixner AuthorDate: Tue, 19 Jan 2021 15:21:35 +01:00 Committer: Thomas Gleixner CommitterDate: Tue, 26 Jan 2021 15:10:58 +01:00 futex: Provide and use pi_state_update_owner() 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 --- kernel/futex.c | 66 ++++++++++++++++++++++++------------------------- 1 file changed, 33 insertions(+), 33 deletions(-) diff --git a/kernel/futex.c b/kernel/futex.c index 5dc8f89..7837f9e 100644 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -763,6 +763,29 @@ static struct futex_pi_state *alloc_pi_state(void) 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); + } +} + static void get_pi_state(struct futex_pi_state *pi_state) { WARN_ON_ONCE(!refcount_inc_not_zero(&pi_state->refcount)); @@ -1521,26 +1544,15 @@ static int wake_futex_pi(u32 __user *uaddr, u32 uval, struct futex_pi_state *pi_ ret = -EINVAL; } - if (ret) - goto out_unlock; - - /* - * This is a point of no return; once we modify the uval there is no - * going back and subsequent operations must not fail. - */ - - 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); - - postunlock = __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); + postunlock = __rt_mutex_futex_unlock(&pi_state->pi_mutex, &wake_q); + } out_unlock: raw_spin_unlock_irq(&pi_state->pi_mutex.wait_lock); @@ -2433,19 +2445,7 @@ retry: * We fixed up user space. Now we need to fix the pi_state * itself. */ - if (pi_state->owner != NULL) { - 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); - } - - pi_state->owner = newowner; - - raw_spin_lock(&newowner->pi_lock); - WARN_ON(!list_empty(&pi_state->list)); - list_add(&pi_state->list, &newowner->pi_state_list); - raw_spin_unlock(&newowner->pi_lock); + pi_state_update_owner(pi_state, newowner); raw_spin_unlock_irq(&pi_state->pi_mutex.wait_lock); return argowner == current;