[PATCH] wifi: mt76: usb: re-enable the rx worker when resuming fails

[YuanZhe Liu]

mt76u_resume_rx() returns as soon as submitting the RX buffers fails, so
the mt76_worker_enable() at the end of the function is never reached and
the RX worker stays parked.  The mt792x USB reset path relies on
mt76u_stop_rx() and mt76u_resume_rx() being a balanced park/unpark pair:
if firmware download fails, mt7925_init_hardware() retries up to ten
times and calls mt792xu_init_reset() again, which parks the already
parked RX worker.  kthread_park() then hits its WARN_ON_ONCE() and
returns -EBUSY:

  WARNING: kernel/kthread.c:710 at kthread_park+0x17b/0x1b0
  Workqueue: events mt7925_init_work
  Call Trace:
   mt76_worker_disable     drivers/net/wireless/mediatek/mt76/util.h:93 [inline]
   mt76u_stop_rx+0x5b/0x2f0 drivers/net/wireless/mediatek/mt76/usb.c:757
   mt792xu_init_reset+0x52/0x80 drivers/net/wireless/mediatek/mt76/mt792x_usb.c:477
   mt7925_init_hardware     drivers/net/wireless/mediatek/mt76/mt7925/init.c:152 [inline]
   mt7925_init_work+0x49b/0x7e0 drivers/net/wireless/mediatek/mt76/mt7925/init.c:196

A stalled RX endpoint makes usb_submit_urb() return -EPIPE, which is the
failure that leaves the MCU unresponsive and triggers the retry loop.
Skip the remaining queues but always re-enable the worker, and still
return the error to the caller.

Fixes: 0d2afe09fad5 ("mt76: mt7921: add mt7921u driver")
Cc: stable at vger.kernel.org
Co-developed-by: Bin Yu <byu at xidian.edu.cn>
Signed-off-by: Bin Yu <byu at xidian.edu.cn>
Co-developed-by: Cheng Wen <wencheng at xidian.edu.cn>
Signed-off-by: Cheng Wen <wencheng at xidian.edu.cn>
Signed-off-by: YuanZhe Liu <25031212351 at stu.xidian.edu.cn>
---
 drivers/net/wireless/mediatek/mt76/usb.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/drivers/net/wireless/mediatek/mt76/usb.c b/drivers/net/wireless/mediatek/mt76/usb.c
index a9af3aa6b80a..1c9bf3679774 100644
--- a/drivers/net/wireless/mediatek/mt76/usb.c
+++ b/drivers/net/wireless/mediatek/mt76/usb.c
@@ -775,23 +775,23 @@ EXPORT_SYMBOL_GPL(mt76u_stop_rx);
 
 int mt76u_resume_rx(struct mt76_dev *dev)
 {
-	int i;
+	int i, err = 0;
 
 	mt76_for_each_q_rx(dev, i) {
 		struct mt76_queue *q = &dev->q_rx[i];
-		int err, j;
+		int j;
 
 		for (j = 0; j < q->ndesc; j++)
 			usb_unpoison_urb(q->entry[j].urb);
 
 		err = mt76u_submit_rx_buffers(dev, i);
 		if (err < 0)
-			return err;
+			break;
 	}
 
 	mt76_worker_enable(&dev->usb.rx_worker);
 
-	return 0;
+	return err;
 }
 EXPORT_SYMBOL_GPL(mt76u_resume_rx);
 
-- 
2.34.1