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authorPeter Zijlstra <peterz@infradead.org>2017-03-22 11:35:53 +0100
committerThomas Gleixner <tglx@linutronix.de>2017-03-23 19:10:08 +0100
commitbf92cf3a5100f5a0d5f9834787b130159397cb22 (patch)
tree8e8fd423f7cd2c6c4d847d24114a021b53fd0160 /kernel/futex.c
parent734009e96d1983ad739e5b656e03430b3660c913 (diff)
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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) <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>
Diffstat (limited to 'kernel/futex.c')
-rw-r--r--kernel/futex.c13
1 files changed, 9 insertions, 4 deletions
diff --git a/kernel/futex.c b/kernel/futex.c
index 3e71d66cb788..3b6dbeecd91b 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,