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From:   Hayes Wang <hayeswang@realtek.com>
To:     <jason-ch.chen@mediatek.com>, <kuba@kernel.org>,
        <davem@davemloft.net>
CC:     <netdev@vger.kernel.org>, <nic_swsd@realtek.com>,
        <linux-kernel@vger.kernel.org>, <linux-usb@vger.kernel.org>,
        Hayes Wang <hayeswang@realtek.com>
Subject: [PATCH net] r8152: avoid to resubmit rx immediately
Date:   Mon, 4 Oct 2021 14:28:58 +0800
Message-ID: <20211004062858.1679-381-nic_swsd@realtek.com>
In-Reply-To: <20210929051812.3107-1-jason-ch.chen@mediatek.com>
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For the situation that the disconnect event comes very late when the
device is unplugged, the driver would resubmit the RX bulk transfer
after getting the callback with -EPROTO immediately and continually.
Finally, soft lockup occurs.

This patch avoids to resubmit RX immediately. It uses a workqueue to
schedule the RX NAPI. And the NAPI would resubmit the RX. It let the
disconnect event have opportunity to stop the submission before soft
lockup.

Reported-by: Jason-ch Chen <jason-ch.chen@mediatek.com>
Tested-by: Jason-ch Chen <jason-ch.chen@mediatek.com>
Signed-off-by: Hayes Wang <hayeswang@realtek.com>
---
 drivers/net/usb/r8152.c | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/drivers/net/usb/r8152.c b/drivers/net/usb/r8152.c
index 60ba9b734055..f329e39100a7 100644
--- a/drivers/net/usb/r8152.c
+++ b/drivers/net/usb/r8152.c
@@ -767,6 +767,7 @@ enum rtl8152_flags {
 	PHY_RESET,
 	SCHEDULE_TASKLET,
 	GREEN_ETHERNET,
+	RX_EPROTO,
 };
 
 #define DEVICE_ID_THINKPAD_THUNDERBOLT3_DOCK_GEN2	0x3082
@@ -1770,6 +1771,14 @@ static void read_bulk_callback(struct urb *urb)
 		rtl_set_unplug(tp);
 		netif_device_detach(tp->netdev);
 		return;
+	case -EPROTO:
+		urb->actual_length = 0;
+		spin_lock_irqsave(&tp->rx_lock, flags);
+		list_add_tail(&agg->list, &tp->rx_done);
+		spin_unlock_irqrestore(&tp->rx_lock, flags);
+		set_bit(RX_EPROTO, &tp->flags);
+		schedule_delayed_work(&tp->schedule, 1);
+		return;
 	case -ENOENT:
 		return;	/* the urb is in unlink state */
 	case -ETIME:
@@ -2425,6 +2434,7 @@ static int rx_bottom(struct r8152 *tp, int budget)
 	if (list_empty(&tp->rx_done))
 		goto out1;
 
+	clear_bit(RX_EPROTO, &tp->flags);
 	INIT_LIST_HEAD(&rx_queue);
 	spin_lock_irqsave(&tp->rx_lock, flags);
 	list_splice_init(&tp->rx_done, &rx_queue);
@@ -2441,7 +2451,7 @@ static int rx_bottom(struct r8152 *tp, int budget)
 
 		agg = list_entry(cursor, struct rx_agg, list);
 		urb = agg->urb;
-		if (urb->actual_length < ETH_ZLEN)
+		if (urb->status != 0 || urb->actual_length < ETH_ZLEN)
 			goto submit;
 
 		agg_free = rtl_get_free_rx(tp, GFP_ATOMIC);
@@ -6643,6 +6653,10 @@ static void rtl_work_func_t(struct work_struct *work)
 	    netif_carrier_ok(tp->netdev))
 		tasklet_schedule(&tp->tx_tl);
 
+	if (test_and_clear_bit(RX_EPROTO, &tp->flags) &&
+	    !list_empty(&tp->rx_done))
+		napi_schedule(&tp->napi);
+
 	mutex_unlock(&tp->control);
 
 out1:
-- 
2.31.1