From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934138AbdCVKo4 (ORCPT ); Wed, 22 Mar 2017 06:44:56 -0400 Received: from bombadil.infradead.org ([65.50.211.133]:33766 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759203AbdCVKoB (ORCPT ); Wed, 22 Mar 2017 06:44:01 -0400 Message-Id: <20170322104151.801778516@infradead.org> User-Agent: quilt/0.63-1 Date: Wed, 22 Mar 2017 11:35:53 +0100 From: Peter Zijlstra To: tglx@linutronix.de Cc: mingo@kernel.org, juri.lelli@arm.com, rostedt@goodmis.org, xlpang@redhat.com, bigeasy@linutronix.de, linux-kernel@vger.kernel.org, mathieu.desnoyers@efficios.com, jdesfossez@efficios.com, bristot@redhat.com, dvhart@infradead.org, peterz@infradead.org Subject: [PATCH -v6 06/13] futex: Cleanup refcounting References: <20170322103547.756091212@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Disposition: inline; filename=peterz-futex-pi-unlock-8.patch Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Since we're going to add more refcount fiddling, introduce get_pi_state() to match the existing put_pi_state(). Signed-off-by: Peter Zijlstra (Intel) --- kernel/futex.c | 13 +++++++++---- 1 file changed, 9 insertions(+), 4 deletions(-) --- 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_ 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 * 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 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 @@ static int futex_requeue(u32 __user *uad * 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,