[PATCH 7/9] padata: use separate workqueues for parallel and serial work

From: Daniel Jordan
Date: Mon Aug 12 2019 - 20:54:09 EST


padata currently uses one per-CPU workqueue per instance for all work.

Prepare for running parallel jobs on an unbound workqueue by introducing
dedicated workqueues for parallel and serial work.

Signed-off-by: Daniel Jordan <daniel.m.jordan@xxxxxxxxxx>
Cc: Herbert Xu <herbert@xxxxxxxxxxxxxxxxxxx>
Cc: Lai Jiangshan <jiangshanlai@xxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Cc: Steffen Klassert <steffen.klassert@xxxxxxxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
Cc: linux-crypto@xxxxxxxxxxxxxxx
Cc: linux-kernel@xxxxxxxxxxxxxxx
---
include/linux/padata.h | 6 ++++--
kernel/padata.c | 28 ++++++++++++++++++----------
2 files changed, 22 insertions(+), 12 deletions(-)

diff --git a/include/linux/padata.h b/include/linux/padata.h
index f7851f8e2190..e7978f8942ca 100644
--- a/include/linux/padata.h
+++ b/include/linux/padata.h
@@ -127,7 +127,8 @@ struct parallel_data {
* struct padata_instance - The overall control structure.
*
* @cpu_notifier: cpu hotplug notifier.
- * @wq: The workqueue in use.
+ * @parallel_wq: The workqueue used for parallel work.
+ * @serial_wq: The workqueue used for serial work.
* @pd: The internal control structure.
* @cpumask: User supplied cpumasks for parallel and serial works.
* @cpumask_change_notifier: Notifiers chain for user-defined notify
@@ -139,7 +140,8 @@ struct parallel_data {
*/
struct padata_instance {
struct hlist_node node;
- struct workqueue_struct *wq;
+ struct workqueue_struct *parallel_wq;
+ struct workqueue_struct *serial_wq;
struct parallel_data *pd;
struct padata_cpumask cpumask;
struct blocking_notifier_head cpumask_change_notifier;
diff --git a/kernel/padata.c b/kernel/padata.c
index 43a837aed04a..1465f094640c 100644
--- a/kernel/padata.c
+++ b/kernel/padata.c
@@ -152,7 +152,7 @@ int padata_do_parallel(struct padata_instance *pinst,
list_add_tail(&padata->list, &queue->parallel.list);
spin_unlock(&queue->parallel.lock);

- queue_work_on(target_cpu, pinst->wq, &queue->work);
+ queue_work_on(target_cpu, pinst->parallel_wq, &queue->work);

out:
rcu_read_unlock_bh();
@@ -261,7 +261,7 @@ static void padata_reorder(struct parallel_data *pd)
list_add_tail(&padata->list, &squeue->serial.list);
spin_unlock(&squeue->serial.lock);

- queue_work_on(cb_cpu, pinst->wq, &squeue->work);
+ queue_work_on(cb_cpu, pinst->serial_wq, &squeue->work);
}

spin_unlock_bh(&pd->lock);
@@ -278,7 +278,7 @@ static void padata_reorder(struct parallel_data *pd)

next_queue = per_cpu_ptr(pd->pqueue, pd->cpu);
if (!list_empty(&next_queue->reorder.list))
- queue_work(pinst->wq, &pd->reorder_work);
+ queue_work(pinst->serial_wq, &pd->reorder_work);
}

static void invoke_padata_reorder(struct work_struct *work)
@@ -828,7 +828,8 @@ static void __padata_free(struct padata_instance *pinst)
padata_free_pd(pinst->pd);
free_cpumask_var(pinst->cpumask.pcpu);
free_cpumask_var(pinst->cpumask.cbcpu);
- destroy_workqueue(pinst->wq);
+ destroy_workqueue(pinst->serial_wq);
+ destroy_workqueue(pinst->parallel_wq);
kfree(pinst);
}

@@ -977,18 +978,23 @@ static struct padata_instance *padata_alloc(const char *name,
if (!pinst)
goto err;

- pinst->wq = alloc_workqueue("%s", WQ_MEM_RECLAIM | WQ_CPU_INTENSIVE,
- 1, name);
- if (!pinst->wq)
+ pinst->parallel_wq = alloc_workqueue("%s_parallel", WQ_MEM_RECLAIM |
+ WQ_CPU_INTENSIVE, 1, name);
+ if (!pinst->parallel_wq)
goto err_free_inst;

get_online_cpus();

- if (!alloc_cpumask_var(&pinst->cpumask.pcpu, GFP_KERNEL))
+ pinst->serial_wq = alloc_workqueue("%s_serial", WQ_MEM_RECLAIM |
+ WQ_CPU_INTENSIVE, 1, name);
+ if (!pinst->serial_wq)
goto err_put_cpus;
+
+ if (!alloc_cpumask_var(&pinst->cpumask.pcpu, GFP_KERNEL))
+ goto err_free_serial_wq;
if (!alloc_cpumask_var(&pinst->cpumask.cbcpu, GFP_KERNEL)) {
free_cpumask_var(pinst->cpumask.pcpu);
- goto err_put_cpus;
+ goto err_free_serial_wq;
}
if (!padata_validate_cpumask(pinst, pcpumask) ||
!padata_validate_cpumask(pinst, cbcpumask))
@@ -1020,9 +1026,11 @@ static struct padata_instance *padata_alloc(const char *name,
err_free_masks:
free_cpumask_var(pinst->cpumask.pcpu);
free_cpumask_var(pinst->cpumask.cbcpu);
+err_free_serial_wq:
+ destroy_workqueue(pinst->serial_wq);
err_put_cpus:
put_online_cpus();
- destroy_workqueue(pinst->wq);
+ destroy_workqueue(pinst->parallel_wq);
err_free_inst:
kfree(pinst);
err:
--
2.22.0