Re: [PATCH v3] rwsem: Support optimistic spinning

From: Tim Chen
Date: Thu May 01 2014 - 12:39:28 EST


On Wed, 2014-04-30 at 20:21 -0700, Davidlohr Bueso wrote:

> +
> +static inline bool rwsem_can_spin_on_owner(struct rw_semaphore *sem)
> +{
> + struct task_struct *owner;
> + bool on_cpu = true;
> +
> + if (need_resched())
> + return 0;
> +
> + rcu_read_lock();
> + owner = ACCESS_ONCE(sem->owner);
> + if (owner)
> + on_cpu = owner->on_cpu;
> + rcu_read_unlock();
> +
> + /*
> + * If lock->owner is not set, the mutex owner may have
> + * just acquired it and not set the owner yet or the mutex

Nitpick. Change the above 2 mutex in comment to rwsem.

> + * has been released.
> + */
> + return on_cpu;
> +}
> +

Tim


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