On 2018/1/19 9:11, Francois Romieu wrote:
Jia-Ju Bai <baijiaju1...@gmail.com> :
[...]
The function rtl8169_start_xmit reads tp->dirty_tx in TX_FRAGS_READY_FOR:
if (unlikely(!TX_FRAGS_READY_FOR(tp, skb_shinfo(skb)->nr_frags))) {
netif_err(tp, drv, dev, "BUG! Tx Ring full when queue awake!\n");
goto err_stop_0;
}
But there is no memory barrier around this code.
Is there a possible data race here?
This code would not even be needed if rtl8169_start_xmit was only your
usual ndo_start_xmit handler: Realtek {ab / re}used it for GSO handling
(see r8169_csum_workaround).
If the test is not a no-op in this GSO context, it's racy.
Thanks for reply.
I didn't clearly understand your meaning...
I wonder whether there is a possible data race and whether a "smp_mb" is
needed before this code?
By the way, do you mean that this code can be removed?
Thanks,
Jia-Ju Bai