Jetpack/kernel/kernel-4.9/rt-patches/0010-futex-Cleanup-refcount...

82 lines
2.5 KiB
Diff

From 3aa828ec128d142f80f3faf7ad79e9630f303b76 Mon Sep 17 00:00:00 2001
From: Peter Zijlstra <peterz@infradead.org>
Date: Wed, 22 Mar 2017 11:35:53 +0100
Subject: [PATCH 010/352] futex: Cleanup refcounting
Upstream commit bf92cf3a5100f5a0d5f9834787b130159397cb22
Add a put_pit_state() as counterpart for get_pi_state() so the refcounting
becomes consistent.
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
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 <tglx@linutronix.de>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
---
kernel/futex.c | 13 +++++++++----
1 file changed, 9 insertions(+), 4 deletions(-)
diff --git a/kernel/futex.c b/kernel/futex.c
index e7e5936..d561ceb 100644
--- a/kernel/futex.c
+++ b/kernel/futex.c
@@ -801,7 +801,7 @@ 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;
@@ -811,6 +811,11 @@ 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.
@@ -855,7 +860,7 @@ 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;
@@ -1102,7 +1107,7 @@ 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;
@@ -2039,7 +2044,7 @@ static int futex_requeue(u32 __user *uaddr1, unsigned int flags,
* 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,
--
2.7.4