On Wed, Mar 22, 2017 at 11:35:56AM +0100, Peter Zijlstra wrote:
> Since there's already two copies of this code, introduce a helper now
> before we get a third instance.
>
> Signed-off-by: Peter Zijlstra (Intel) <pet...@infradead.org>
An easy one!
Reviewed-by: Darren Hart (VMware) <dvh...@infradead.org>
> ---
> kernel/futex.c | 5 +----
> kernel/locking/rtmutex.c | 12 +++++++++---
> kernel/locking/rtmutex_common.h | 1 +
> 3 files changed, 11 insertions(+), 7 deletions(-)
>
> --- a/kernel/futex.c
> +++ b/kernel/futex.c
> @@ -2956,10 +2956,7 @@ static int futex_wait_requeue_pi(u32 __u
> * The waiter is allocated on our stack, manipulated by the requeue
> * code while we sleep on uaddr.
> */
> - debug_rt_mutex_init_waiter(&rt_waiter);
> - RB_CLEAR_NODE(&rt_waiter.pi_tree_entry);
> - RB_CLEAR_NODE(&rt_waiter.tree_entry);
> - rt_waiter.task = NULL;
> + rt_mutex_init_waiter(&rt_waiter);
>
> ret = get_futex_key(uaddr2, flags & FLAGS_SHARED, &key2, VERIFY_WRITE);
> if (unlikely(ret != 0))
> --- a/kernel/locking/rtmutex.c
> +++ b/kernel/locking/rtmutex.c
> @@ -1153,6 +1153,14 @@ void rt_mutex_adjust_pi(struct task_stru
> next_lock, NULL, task);
> }
>
> +void rt_mutex_init_waiter(struct rt_mutex_waiter *waiter)
> +{
> + debug_rt_mutex_init_waiter(waiter);
> + RB_CLEAR_NODE(&waiter->pi_tree_entry);
> + RB_CLEAR_NODE(&waiter->tree_entry);
> + waiter->task = NULL;
> +}
> +
> /**
> * __rt_mutex_slowlock() - Perform the wait-wake-try-to-take loop
> * @lock: the rt_mutex to take
> @@ -1235,9 +1243,7 @@ rt_mutex_slowlock(struct rt_mutex *lock,
> unsigned long flags;
> int ret = 0;
>
> - debug_rt_mutex_init_waiter(&waiter);
> - RB_CLEAR_NODE(&waiter.pi_tree_entry);
> - RB_CLEAR_NODE(&waiter.tree_entry);
> + rt_mutex_init_waiter(&waiter);
Verified that despite not assigning waiter.task to NULL here, it does no harm to
do so as it is initialized by task_blocks_on_rt_mutex before it is referenced.
>
> /*
> * Technically we could use raw_spin_[un]lock_irq() here, but this can
> --- a/kernel/locking/rtmutex_common.h
> +++ b/kernel/locking/rtmutex_common.h
> @@ -103,6 +103,7 @@ extern void rt_mutex_init_proxy_locked(s
> struct task_struct *proxy_owner);
> extern void rt_mutex_proxy_unlock(struct rt_mutex *lock,
> struct task_struct *proxy_owner);
> +extern void rt_mutex_init_waiter(struct rt_mutex_waiter *waiter);
> extern int rt_mutex_start_proxy_lock(struct rt_mutex *lock,
> struct rt_mutex_waiter *waiter,
> struct task_struct *task);
>
>
>
--
Darren Hart
VMware Open Source Technology Center
