From: Peter Zijlstra <peterz@infradead.org>
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 -v5 08/14] futex: Cleanup refcounting
Date: Sat, 04 Mar 2017 10:27:25 +0100 [thread overview]
Message-ID: <20170304093559.283908209@infradead.org> (raw)
In-Reply-To: 20170304092717.762954142@infradead.org
[-- Attachment #1: peterz-futex-pi-unlock-8.patch --]
[-- Type: text/plain, Size: 1760 bytes --]
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) <peterz@infradead.org>
---
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,
next prev parent reply other threads:[~2017-03-04 11:44 UTC|newest]
Thread overview: 36+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-03-04 9:27 [PATCH -v5 00/14] the saga of FUTEX_UNLOCK_PI wobbles continues Peter Zijlstra
2017-03-04 9:27 ` [PATCH -v5 01/14] futex: Fix potential use-after-free in FUTEX_REQUEUE_PI Peter Zijlstra
2017-03-14 20:48 ` [tip:locking/urgent] " tip-bot for Peter Zijlstra
2017-03-04 9:27 ` [PATCH -v5 02/14] futex: Add missing error handling to FUTEX_REQUEUE_PI Peter Zijlstra
2017-03-14 20:49 ` [tip:locking/urgent] " tip-bot for Peter Zijlstra
2017-03-04 9:27 ` [PATCH -v5 03/14] futex: Cleanup variable names for futex_top_waiter() Peter Zijlstra
2017-03-04 9:27 ` [PATCH -v5 04/14] futex: Use smp_store_release() in mark_wake_futex() Peter Zijlstra
2017-03-04 9:27 ` [PATCH -v5 05/14] futex: Remove rt_mutex_deadlock_account_*() Peter Zijlstra
2017-03-04 9:27 ` [PATCH -v5 06/14] futex,rt_mutex: Provide futex specific rt_mutex API Peter Zijlstra
2017-03-04 9:27 ` [PATCH -v5 07/14] futex: Change locking rules Peter Zijlstra
2017-03-07 13:22 ` Thomas Gleixner
2017-03-07 16:47 ` Sebastian Andrzej Siewior
2017-03-07 18:01 ` Peter Zijlstra
2017-03-04 9:27 ` Peter Zijlstra [this message]
2017-03-04 9:27 ` [PATCH -v5 09/14] futex: Rework inconsistent rt_mutex/futex_q state Peter Zijlstra
2017-03-07 13:26 ` Thomas Gleixner
2017-03-04 9:27 ` [PATCH -v5 10/14] futex: Pull rt_mutex_futex_unlock() out from under hb->lock Peter Zijlstra
2017-03-07 14:08 ` Thomas Gleixner
2017-03-07 18:01 ` Peter Zijlstra
2017-03-04 9:27 ` [PATCH -v5 11/14] futex,rt_mutex: Introduce rt_mutex_init_waiter() Peter Zijlstra
2017-03-04 9:27 ` [PATCH -v5 12/14] futex,rt_mutex: Restructure rt_mutex_finish_proxy_lock() Peter Zijlstra
2017-03-07 14:18 ` Thomas Gleixner
2017-03-07 17:57 ` Peter Zijlstra
2017-03-07 17:59 ` Thomas Gleixner
2017-03-08 15:29 ` [PATCH] futex: move debug_rt_mutex_free_waiter() further down Sebastian Andrzej Siewior
2017-03-08 15:37 ` Sebastian Andrzej Siewior
2017-03-08 16:21 ` Steven Rostedt
2017-03-08 16:20 ` Steven Rostedt
2017-03-13 9:16 ` Peter Zijlstra
2017-03-04 9:27 ` [PATCH -v5 13/14] futex: Rework futex_lock_pi() to use rt_mutex_*_proxy_lock() Peter Zijlstra
2017-03-04 9:27 ` [PATCH -v5 14/14] futex: futex_unlock_pi() determinism Peter Zijlstra
2017-03-07 14:31 ` Thomas Gleixner
2017-03-07 17:59 ` Peter Zijlstra
2017-03-13 9:25 ` Peter Zijlstra
2017-03-13 14:25 ` Thomas Gleixner
2017-03-13 15:11 ` Peter Zijlstra
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