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@huawei.com>
Reviewed-by: Alexander Duyck <alexanderduyck@fb.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/drivers/isdn/hardware/mISDN/hfcsusb.c b/drivers/isdn/hardware/mISDN/hfcsusb.c
index 651f2f8..1efd179 100644 (file)
--- 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;