On Tue, Jan 7, 2020 at 4:08 PM <yhchuang@xxxxxxxxxxx> wrote:
>
> From: Yan-Hsuan Chuang <yhchuang@xxxxxxxxxxx>
>
> Sometimes the TX queue may be empty and we could possible
> dequeue a NULL pointer, crash the kernel. If the skb is NULL
> then there is nothing to do, just leave the ISR.
>
> And the TX queue should not be empty here, so print an error
> to see if there is anything wrong for DMA ring.
>
> Fixes: e3037485c68e ("rtw88: new Realtek 802.11ac driver")
> Signed-off-by: Yan-Hsuan Chuang <yhchuang@xxxxxxxxxxx>
> ---
> drivers/net/wireless/realtek/rtw88/pci.c | 5 +++++
> 1 file changed, 5 insertions(+)
>
> diff --git a/drivers/net/wireless/realtek/rtw88/pci.c b/drivers/net/wireless/realtek/rtw88/pci.c
> index a58e8276a41a..a6746b5a9ff2 100644
> --- a/drivers/net/wireless/realtek/rtw88/pci.c
> +++ b/drivers/net/wireless/realtek/rtw88/pci.c
> @@ -832,6 +832,11 @@ static void rtw_pci_tx_isr(struct rtw_dev *rtwdev, struct rtw_pci *rtwpci,
>
> while (count--) {
> skb = skb_dequeue(&ring->queue);
> + if (!skb) {
> + rtw_err(rtwdev, "failed to dequeue %d skb TX queue %d, BD=0x%08x, rp %d -> %d\n",
> + count, hw_queue, bd_idx, ring->r.rp, cur_rp);
> + break;
> + }
> tx_data = rtw_pci_get_tx_data(skb);
> pci_unmap_single(rtwpci->pdev, tx_data->dma, skb->len,
> PCI_DMA_TODEVICE);
> --
> 2.17.1
>
Maybe we can simply do 'while (count -- &&
!skb_queue_empty(&ring->queue))' to achieve the same thing?
I don't think it worths to raise an error unless the count is expected
to exactly match the queue length in any
circumstances.
Chris
