netdev - [PATCH net v2 1/3] mISDN: hfcsusb: don't call dev_kfree_skb/kfree_skb() under spin_lock

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Date:   Mon, 12 Dec 2022 16:41:37 +0800
From:   Yang Yingliang <yangyingliang@...wei.com>
To:     <netdev@...r.kernel.org>
CC:     <isdn@...ux-pingi.de>, <davem@...emloft.net>, <kuba@...nel.org>,
        <jiri@...nulli.us>, Yang Yingliang <yangyingliang@...wei.com>,
        Martin Bachem <m.bachem@....de>
Subject: [PATCH net v2 1/3] mISDN: hfcsusb: don't call dev_kfree_skb/kfree_skb() under spin_lock_irqsave()

It is not allowed to call kfree_skb() or consume_skb() from hardware
interrupt context or with hardware interrupts being disabled.

It should use dev_kfree_skb_irq() or dev_consume_skb_irq() instead.
The difference between them is free reason, dev_kfree_skb_irq() means
the SKB is dropped in error and dev_consume_skb_irq() means the SKB
is consumed in normal.

skb_queue_purge() is called under spin_lock_irqsave() in hfcusb_l2l1D(),
kfree_skb() is called in it, to fix this, use skb_queue_splice_init()
to move the dch->squeue to a free queue, also enqueue the tx_skb and
rx_skb, at last calling __skb_queue_purge() to free the SKBs afer unlock.

In tx_iso_complete(), dev_kfree_skb() is called to consume the transmitted
SKB, so replace it with dev_consume_skb_irq().

Fixes: 69f52adb2d53 ("mISDN: Add HFC USB driver")
Signed-off-by: Yang Yingliang <yangyingliang@...wei.com>
---
 drivers/isdn/hardware/mISDN/hfcsusb.c | 12 ++++++++----
 1 file changed, 8 insertions(+), 4 deletions(-)

diff --git a/drivers/isdn/hardware/mISDN/hfcsusb.c b/drivers/isdn/hardware/mISDN/hfcsusb.c
index 651f2f8f685b..1efd17979f24 100644
--- a/drivers/isdn/hardware/mISDN/hfcsusb.c
+++ b/drivers/isdn/hardware/mISDN/hfcsusb.c
@@ -326,20 +326,24 @@ hfcusb_l2l1D(struct mISDNchannel *ch, struct sk_buff *skb)
 		test_and_clear_bit(FLG_L2_ACTIVATED, &dch->Flags);
 
 		if (hw->protocol == ISDN_P_NT_S0) {
+			struct sk_buff_head free_queue;
+
+			__skb_queue_head_init(&free_queue);
 			hfcsusb_ph_command(hw, HFC_L1_DEACTIVATE_NT);
 			spin_lock_irqsave(&hw->lock, flags);
-			skb_queue_purge(&dch->squeue);
+			skb_queue_splice_init(&dch->squeue, &free_queue);
 			if (dch->tx_skb) {
-				dev_kfree_skb(dch->tx_skb);
+				__skb_queue_tail(&free_queue, dch->tx_skb);
 				dch->tx_skb = NULL;
 			}
 			dch->tx_idx = 0;
 			if (dch->rx_skb) {
-				dev_kfree_skb(dch->rx_skb);
+				__skb_queue_tail(&free_queue, dch->rx_skb);
 				dch->rx_skb = NULL;
 			}
 			test_and_clear_bit(FLG_TX_BUSY, &dch->Flags);
 			spin_unlock_irqrestore(&hw->lock, flags);
+			__skb_queue_purge(&free_queue);
 #ifdef FIXME
 			if (test_and_clear_bit(FLG_L1_BUSY, &dch->Flags))
 				dchannel_sched_event(&hc->dch, D_CLEARBUSY);
@@ -1330,7 +1334,7 @@ tx_iso_complete(struct urb *urb)
 					printk("\n");
 				}
 
-				dev_kfree_skb(tx_skb);
+				dev_consume_skb_irq(tx_skb);
 				tx_skb = NULL;
 				if (fifo->dch && get_next_dframe(fifo->dch))
 					tx_skb = fifo->dch->tx_skb;
-- 
2.25.1