From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S935828AbdCWSYZ (ORCPT ); Thu, 23 Mar 2017 14:24:25 -0400 Received: from terminus.zytor.com ([65.50.211.136]:41531 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S935747AbdCWSYY (ORCPT ); Thu, 23 Mar 2017 14:24:24 -0400 Date: Thu, 23 Mar 2017 11:21:47 -0700 From: tip-bot for Peter Zijlstra Message-ID: Cc: peterz@infradead.org, linux-kernel@vger.kernel.org, mingo@kernel.org, hpa@zytor.com, tglx@linutronix.de Reply-To: tglx@linutronix.de, hpa@zytor.com, linux-kernel@vger.kernel.org, mingo@kernel.org, peterz@infradead.org In-Reply-To: <20170322104151.801778516@infradead.org> References: <20170322104151.801778516@infradead.org> To: linux-tip-commits@vger.kernel.org Subject: [tip:locking/core] futex: Cleanup refcounting Git-Commit-ID: bf92cf3a5100f5a0d5f9834787b130159397cb22 X-Mailer: tip-git-log-daemon Robot-ID: Robot-Unsubscribe: Contact to get blacklisted from these emails MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Commit-ID: bf92cf3a5100f5a0d5f9834787b130159397cb22 Gitweb: http://git.kernel.org/tip/bf92cf3a5100f5a0d5f9834787b130159397cb22 Author: Peter Zijlstra AuthorDate: Wed, 22 Mar 2017 11:35:53 +0100 Committer: Thomas Gleixner CommitDate: Thu, 23 Mar 2017 19:10:08 +0100 futex: Cleanup refcounting Add a put_pit_state() as counterpart for get_pi_state() so the refcounting becomes consistent. Signed-off-by: Peter Zijlstra (Intel) Cc: juri.lelli@arm.com Cc: bigeasy@linutronix.de Cc: xlpang@redhat.com Cc: rostedt@goodmis.org Cc: mathieu.desnoyers@efficios.com Cc: jdesfossez@efficios.com Cc: dvhart@infradead.org Cc: bristot@redhat.com Link: http://lkml.kernel.org/r/20170322104151.801778516@infradead.org Signed-off-by: Thomas Gleixner --- kernel/futex.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) diff --git a/kernel/futex.c b/kernel/futex.c index 3e71d66..3b6dbee 100644 --- a/kernel/futex.c +++ b/kernel/futex.c @@ -802,7 +802,7 @@ static int refill_pi_state_cache(void) return 0; } -static struct futex_pi_state * alloc_pi_state(void) +static struct futex_pi_state *alloc_pi_state(void) { struct futex_pi_state *pi_state = current->pi_state_cache; @@ -812,6 +812,11 @@ static struct futex_pi_state * alloc_pi_state(void) return pi_state; } +static void get_pi_state(struct futex_pi_state *pi_state) +{ + WARN_ON_ONCE(!atomic_inc_not_zero(&pi_state->refcount)); +} + /* * Drops a reference to the pi_state object and frees or caches it * when the last reference is gone. @@ -856,7 +861,7 @@ static void put_pi_state(struct futex_pi_state *pi_state) * Look up the task based on what TID userspace gave us. * We dont trust it. */ -static struct task_struct * futex_find_get_task(pid_t pid) +static struct task_struct *futex_find_get_task(pid_t pid) { struct task_struct *p; @@ -1103,7 +1108,7 @@ static int attach_to_pi_state(u32 __user *uaddr, u32 uval, goto out_einval; out_attach: - atomic_inc(&pi_state->refcount); + get_pi_state(pi_state); raw_spin_unlock_irq(&pi_state->pi_mutex.wait_lock); *ps = pi_state; return 0; @@ -1990,7 +1995,7 @@ retry_private: * refcount on the pi_state and store the pointer in * the futex_q object of the waiter. */ - atomic_inc(&pi_state->refcount); + get_pi_state(pi_state); this->pi_state = pi_state; ret = rt_mutex_start_proxy_lock(&pi_state->pi_mutex, this->rt_waiter,