On Thu, May 12, 2022 at 03:04:30AM +0000, Joel Fernandes (Google) wrote:
> This will be used in kfree_rcu() later to make it do call_rcu() lazily.
Given that kfree_rcu() does its own laziness in filling in the page
of pointers, do we really need to add additional laziness?
Or are you measuring a significant benefit from doing this?
Thanx, Paul
> Signed-off-by: Joel Fernandes (Google) <joel@xxxxxxxxxxxxxxxxx>
> ---
> include/linux/workqueue.h | 1 +
> kernel/workqueue.c | 25 +++++++++++++++++++++++++
> 2 files changed, 26 insertions(+)
>
> diff --git a/include/linux/workqueue.h b/include/linux/workqueue.h
> index 7fee9b6cfede..2678a6b5b3f3 100644
> --- a/include/linux/workqueue.h
> +++ b/include/linux/workqueue.h
> @@ -444,6 +444,7 @@ extern bool queue_delayed_work_on(int cpu, struct workqueue_struct *wq,
> extern bool mod_delayed_work_on(int cpu, struct workqueue_struct *wq,
> struct delayed_work *dwork, unsigned long delay);
> extern bool queue_rcu_work(struct workqueue_struct *wq, struct rcu_work *rwork);
> +extern bool queue_rcu_work_lazy(struct workqueue_struct *wq, struct rcu_work *rwork);
>
> extern void flush_workqueue(struct workqueue_struct *wq);
> extern void drain_workqueue(struct workqueue_struct *wq);
> diff --git a/kernel/workqueue.c b/kernel/workqueue.c
> index 33f1106b4f99..9444949cc148 100644
> --- a/kernel/workqueue.c
> +++ b/kernel/workqueue.c
> @@ -1796,6 +1796,31 @@ bool queue_rcu_work(struct workqueue_struct *wq, struct rcu_work *rwork)
> }
> EXPORT_SYMBOL(queue_rcu_work);
>
> +/**
> + * queue_rcu_work_lazy - queue work after a RCU grace period
> + * @wq: workqueue to use
> + * @rwork: work to queue
> + *
> + * Return: %false if @rwork was already pending, %true otherwise. Note
> + * that a full RCU grace period is guaranteed only after a %true return.
> + * While @rwork is guaranteed to be executed after a %false return, the
> + * execution may happen before a full RCU grace period has passed.
> + */
> +bool queue_rcu_work_lazy(struct workqueue_struct *wq, struct rcu_work *rwork)
> +{
> + struct work_struct *work = &rwork->work;
> +
> + if (!test_and_set_bit(WORK_STRUCT_PENDING_BIT, work_data_bits(work))) {
> + rwork->wq = wq;
> + call_rcu_lazy(&rwork->rcu, rcu_work_rcufn);
> + return true;
> + }
> +
> + return false;
> +}
> +EXPORT_SYMBOL(queue_rcu_work_lazy);
> +
> +
> /**
> * worker_enter_idle - enter idle state
> * @worker: worker which is entering idle state
> --
> 2.36.0.550.gb090851708-goog
>
