[PATCH v2] wfx: avoid flush_workqueue(system_highpri_wq) usage

[Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>]

Flushing system-wide workqueues is dangerous and will be forbidden.
Replace system_highpri_wq with per "struct wfx_dev" bh_wq.

Signed-off-by: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
---
Note: This patch is only compile tested.

Changes in v2:
  Use per "struct wfx_dev" workqueue.

 drivers/net/wireless/silabs/wfx/bh.c     | 6 +++---
 drivers/net/wireless/silabs/wfx/hif_tx.c | 2 +-
 drivers/net/wireless/silabs/wfx/main.c   | 6 ++++++
 drivers/net/wireless/silabs/wfx/wfx.h    | 1 +
 4 files changed, 11 insertions(+), 4 deletions(-)

diff --git a/drivers/net/wireless/silabs/wfx/bh.c b/drivers/net/wireless/silabs/wfx/bh.c
index bcea9d5b119c..21dfdcf9cc27 100644
--- a/drivers/net/wireless/silabs/wfx/bh.c
+++ b/drivers/net/wireless/silabs/wfx/bh.c
@@ -267,7 +267,7 @@ void wfx_bh_request_rx(struct wfx_dev *wdev)
 	wfx_control_reg_read(wdev, &cur);
 	prev = atomic_xchg(&wdev->hif.ctrl_reg, cur);
 	complete(&wdev->hif.ctrl_ready);
-	queue_work(system_highpri_wq, &wdev->hif.bh);
+	queue_work(wdev->bh_wq, &wdev->hif.bh);
 
 	if (!(cur & CTRL_NEXT_LEN_MASK))
 		dev_err(wdev->dev, "unexpected control register value: length field is 0: %04x\n",
@@ -280,7 +280,7 @@ void wfx_bh_request_rx(struct wfx_dev *wdev)
 /* Driver want to send data */
 void wfx_bh_request_tx(struct wfx_dev *wdev)
 {
-	queue_work(system_highpri_wq, &wdev->hif.bh);
+	queue_work(wdev->bh_wq, &wdev->hif.bh);
 }
 
 /* If IRQ is not available, this function allow to manually poll the control register and simulate
@@ -295,7 +295,7 @@ void wfx_bh_poll_irq(struct wfx_dev *wdev)
 	u32 reg;
 
 	WARN(!wdev->poll_irq, "unexpected IRQ polling can mask IRQ");
-	flush_workqueue(system_highpri_wq);
+	flush_workqueue(wdev->bh_wq);
 	start = ktime_get();
 	for (;;) {
 		wfx_control_reg_read(wdev, &reg);
diff --git a/drivers/net/wireless/silabs/wfx/hif_tx.c b/drivers/net/wireless/silabs/wfx/hif_tx.c
index 9c653d0e9034..d35dd940d968 100644
--- a/drivers/net/wireless/silabs/wfx/hif_tx.c
+++ b/drivers/net/wireless/silabs/wfx/hif_tx.c
@@ -73,7 +73,7 @@ int wfx_cmd_send(struct wfx_dev *wdev, struct wfx_hif_msg *request,
 
 	if (no_reply) {
 		/* Chip won't reply. Ensure the wq has send the buffer before to continue. */
-		flush_workqueue(system_highpri_wq);
+		flush_workqueue(wdev->bh_wq);
 		ret = 0;
 		goto end;
 	}
diff --git a/drivers/net/wireless/silabs/wfx/main.c b/drivers/net/wireless/silabs/wfx/main.c
index e575a81ca2ca..e015bfb8d221 100644
--- a/drivers/net/wireless/silabs/wfx/main.c
+++ b/drivers/net/wireless/silabs/wfx/main.c
@@ -345,6 +345,10 @@ int wfx_probe(struct wfx_dev *wdev)
 	wdev->pdata.gpio_wakeup = NULL;
 	wdev->poll_irq = true;
 
+	wdev->bh_wq = alloc_workqueue("wfx_bh_wq", WQ_HIGHPRI, 0);
+	if (!wdev->bh_wq)
+		return -ENOMEM;
+
 	wfx_bh_register(wdev);
 
 	err = wfx_init_device(wdev);
@@ -458,6 +462,7 @@ int wfx_probe(struct wfx_dev *wdev)
 	wdev->hwbus_ops->irq_unsubscribe(wdev->hwbus_priv);
 bh_unregister:
 	wfx_bh_unregister(wdev);
+	destroy_workqueue(wdev->bh_wq);
 	return err;
 }
 
@@ -467,6 +472,7 @@ void wfx_release(struct wfx_dev *wdev)
 	wfx_hif_shutdown(wdev);
 	wdev->hwbus_ops->irq_unsubscribe(wdev->hwbus_priv);
 	wfx_bh_unregister(wdev);
+	destroy_workqueue(wdev->bh_wq);
 }
 
 static int __init wfx_core_init(void)
diff --git a/drivers/net/wireless/silabs/wfx/wfx.h b/drivers/net/wireless/silabs/wfx/wfx.h
index 6594cc647c2f..6f5e95dae21f 100644
--- a/drivers/net/wireless/silabs/wfx/wfx.h
+++ b/drivers/net/wireless/silabs/wfx/wfx.h
@@ -57,6 +57,7 @@ struct wfx_dev {
 	struct mutex               rx_stats_lock;
 	struct wfx_hif_tx_power_loop_info tx_power_loop_info;
 	struct mutex               tx_power_loop_info_lock;
+	struct workqueue_struct    *bh_wq;
 };
 
 struct wfx_vif {
-- 
2.34.1