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Date: Mon, 4 Jan 2021 20:58:39 -0600
From: Mike Ximing Chen <mike.ximing.chen@...el.com>
To: linux-kernel@...r.kernel.org
Cc: arnd@...db.de, gregkh@...uxfoundation.org,
dan.j.williams@...el.com, pierre-louis.bossart@...ux.intel.com,
Gage Eads <gage.eads@...el.com>
Subject: [PATCH v8 20/20] dlb: queue map/unmap workqueue
Add workqueue support for asynchronous queue map/unmap operations.
When mapping or unmapped a queue, it's possible that the thread that
requires the map/unmap is the same one which is responsible for doing the
processing that would quiesce the queue/port, thus the driver may have to
complete the operation asynchronously.
To that end, the driver uses a workqueue that periodically checks whether
any outstanding operations can be completed. This workqueue function is
only scheduled when there is at least one outstanding map/unmap operation.
Signed-off-by: Gage Eads <gage.eads@...el.com>
Signed-off-by: Mike Ximing Chen <mike.ximing.chen@...el.com>
Reviewed-by: Björn Töpel <bjorn.topel@...el.com>
Reviewed-by: Dan Williams <dan.j.williams@...el.com>
---
drivers/misc/dlb/dlb_main.c | 5 ++
drivers/misc/dlb/dlb_main.h | 2 +
drivers/misc/dlb/dlb_resource.c | 110 +++++++++++++++++++++++++++++++-
drivers/misc/dlb/dlb_resource.h | 2 +
4 files changed, 117 insertions(+), 2 deletions(-)
diff --git a/drivers/misc/dlb/dlb_main.c b/drivers/misc/dlb/dlb_main.c
index 97aae4c880d2..2d96cff9223c 100644
--- a/drivers/misc/dlb/dlb_main.c
+++ b/drivers/misc/dlb/dlb_main.c
@@ -458,6 +458,9 @@ static int dlb_probe(struct pci_dev *pdev,
dlb->ops->init_hardware(dlb);
+ /* Initialize a workqueue for queue-port linking. */
+ dlb_init_work(dlb);
+
/*
* Undo the 'get' operation by the PCI layer during probe and
* (if PF) immediately suspend the device. Since the device is only
@@ -617,6 +620,8 @@ static int __init dlb_init_module(void)
static void __exit dlb_exit_module(void)
{
+ flush_scheduled_work();
+
pci_unregister_driver(&dlb_pci_driver);
cdev_del(&dlb_cdev);
diff --git a/drivers/misc/dlb/dlb_main.h b/drivers/misc/dlb/dlb_main.h
index 28fef9897e40..35047a8d76ac 100644
--- a/drivers/misc/dlb/dlb_main.h
+++ b/drivers/misc/dlb/dlb_main.h
@@ -139,11 +139,13 @@ struct dlb {
* hardware registers.
*/
struct mutex resource_mutex;
+ struct work_struct work;
enum dlb_device_type type;
int id;
u32 inode_cnt;
dev_t dev_number;
u8 domain_reset_failed;
+ u8 worker_launched;
};
int dlb_init_domain(struct dlb *dlb, u32 domain_id);
diff --git a/drivers/misc/dlb/dlb_resource.c b/drivers/misc/dlb/dlb_resource.c
index 6994fe90bb25..f6dd500645d1 100644
--- a/drivers/misc/dlb/dlb_resource.c
+++ b/drivers/misc/dlb/dlb_resource.c
@@ -2602,6 +2602,61 @@ static int dlb_ldb_port_finish_map_qid_dynamic(struct dlb_hw *hw,
return 0;
}
+static unsigned int dlb_finish_unmap_qid_procedures(struct dlb_hw *hw);
+static unsigned int dlb_finish_map_qid_procedures(struct dlb_hw *hw);
+
+/*
+ * The workqueue callback runs until it completes all outstanding QID->CQ
+ * map and unmap requests. To prevent deadlock, this function gives other
+ * threads a chance to grab the resource mutex and configure hardware.
+ */
+static void dlb_complete_queue_map_unmap(struct work_struct *work)
+{
+ struct dlb *dlb = container_of(work, struct dlb, work);
+ int ret;
+
+ mutex_lock(&dlb->resource_mutex);
+
+ ret = dlb_finish_unmap_qid_procedures(&dlb->hw);
+ ret += dlb_finish_map_qid_procedures(&dlb->hw);
+
+ if (ret != 0)
+ /*
+ * Relinquish the CPU so the application can process its CQs,
+ * so this function doesn't deadlock.
+ */
+ schedule_work(&dlb->work);
+ else
+ dlb->worker_launched = false;
+
+ mutex_unlock(&dlb->resource_mutex);
+}
+
+void dlb_init_work(struct dlb *dlb)
+{
+ INIT_WORK(&dlb->work, dlb_complete_queue_map_unmap);
+}
+
+/**
+ * dlb_schedule_work() - launch a thread to process pending map and unmap work
+ * @hw: dlb_hw handle for a particular device.
+ *
+ * This function launches a kernel thread that will run until all pending
+ * map and unmap procedures are complete.
+ */
+static void dlb_schedule_work(struct dlb_hw *hw)
+{
+ struct dlb *dlb = container_of(hw, struct dlb, hw);
+
+ /* Nothing to do if the worker is already running */
+ if (dlb->worker_launched)
+ return;
+
+ schedule_work(&dlb->work);
+
+ dlb->worker_launched = true;
+}
+
/**
* dlb_ldb_port_map_qid_dynamic() - perform a "dynamic" QID->CQ mapping
* @hw: dlb_hw handle for a particular device.
@@ -2654,8 +2709,16 @@ static int dlb_ldb_port_map_qid_dynamic(struct dlb_hw *hw,
infl_cnt = DLB_CSR_RD(hw, LSP_QID_LDB_INFL_CNT(queue->id.phys_id));
- if (BITS_GET(infl_cnt, LSP_QID_LDB_INFL_CNT_COUNT))
+ if (BITS_GET(infl_cnt, LSP_QID_LDB_INFL_CNT_COUNT)) {
+ /*
+ * The queue is owed completions so it's not safe to map it
+ * yet. Schedule a kernel thread to complete the mapping later,
+ * once software has completed all the queue's inflight events.
+ */
+ dlb_schedule_work(hw);
+
return 1;
+ }
/*
* Disable the affected CQ, and the CQs already mapped to the QID,
@@ -2678,6 +2741,13 @@ static int dlb_ldb_port_map_qid_dynamic(struct dlb_hw *hw,
dlb_ldb_queue_enable_mapped_cqs(hw, domain, queue);
+ /*
+ * The queue is owed completions so it's not safe to map it
+ * yet. Schedule a kernel thread to complete the mapping later,
+ * once software has completed all the queue's inflight events.
+ */
+ dlb_schedule_work(hw);
+
return 1;
}
@@ -3394,6 +3464,20 @@ dlb_domain_finish_unmap_qid_procedures(struct dlb_hw *hw,
return domain->num_pending_removals;
}
+static unsigned int dlb_finish_unmap_qid_procedures(struct dlb_hw *hw)
+{
+ int i, num = 0;
+
+ /* Finish queue unmap jobs for any domain that needs it */
+ for (i = 0; i < DLB_MAX_NUM_DOMAINS; i++) {
+ struct dlb_hw_domain *domain = &hw->domains[i];
+
+ num += dlb_domain_finish_unmap_qid_procedures(hw, domain);
+ }
+
+ return num;
+}
+
static void dlb_domain_finish_map_port(struct dlb_hw *hw,
struct dlb_hw_domain *domain,
struct dlb_ldb_port *port)
@@ -3470,6 +3554,20 @@ dlb_domain_finish_map_qid_procedures(struct dlb_hw *hw,
return domain->num_pending_additions;
}
+static unsigned int dlb_finish_map_qid_procedures(struct dlb_hw *hw)
+{
+ int i, num = 0;
+
+ /* Finish queue map jobs for any domain that needs it */
+ for (i = 0; i < DLB_MAX_NUM_DOMAINS; i++) {
+ struct dlb_hw_domain *domain = &hw->domains[i];
+
+ num += dlb_domain_finish_map_qid_procedures(hw, domain);
+ }
+
+ return num;
+}
+
static void dlb_log_map_qid(struct dlb_hw *hw,
u32 domain_id,
struct dlb_map_qid_args *args,
@@ -3750,6 +3848,7 @@ int dlb_hw_unmap_qid(struct dlb_hw *hw,
struct dlb_ldb_queue *queue;
enum dlb_qid_map_state st;
struct dlb_ldb_port *port;
+ bool unmap_complete;
int i, ret;
dlb_log_unmap_qid(hw, domain_id, args, vdev_req, vdev_id);
@@ -3831,7 +3930,14 @@ int dlb_hw_unmap_qid(struct dlb_hw *hw,
* outstanding inflights. If that's not the case, this will fail and
* the unmapping will be completed at a later time.
*/
- dlb_domain_finish_unmap_port(hw, domain, port);
+ unmap_complete = dlb_domain_finish_unmap_port(hw, domain, port);
+
+ /*
+ * If the unmapping couldn't complete immediately, launch the worker
+ * thread (if it isn't already launched) to finish it later.
+ */
+ if (!unmap_complete)
+ dlb_schedule_work(hw);
unmap_qid_done:
resp->status = 0;
diff --git a/drivers/misc/dlb/dlb_resource.h b/drivers/misc/dlb/dlb_resource.h
index 5fbc9d0b5e96..1f4c8efcfc28 100644
--- a/drivers/misc/dlb/dlb_resource.h
+++ b/drivers/misc/dlb/dlb_resource.h
@@ -120,4 +120,6 @@ void dlb_hw_enable_sparse_ldb_cq_mode(struct dlb_hw *hw);
void dlb_hw_enable_sparse_dir_cq_mode(struct dlb_hw *hw);
+void dlb_init_work(struct dlb *dlb);
+
#endif /* __DLB_RESOURCE_H */
--
2.17.1
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