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futex: Cleanup refcounting

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From: Peter Zijlstra <peterz@infradead.org>

commit bf92cf3a5100f5a0d5f9834787b130159397cb22 upstream.

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: Ben Hutchings <ben@decadent.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Ben Hutchings 2021-03-01 18:31:22 +01:00 committed by Greg Kroah-Hartman
parent bfefc9e38d
commit 921a7e30b1
1 changed files with 9 additions and 4 deletions
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13
kernel/futex.c
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@ -827,7 +827,7 @@ 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;
@ -860,6 +860,11 @@ static void pi_state_update_owner(struct futex_pi_state *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.
@ -901,7 +906,7 @@ 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;
@ -1149,7 +1154,7 @@ 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;
@ -2210,7 +2215,7 @@ 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,