Messages in this thread | | | Subject | Re: net: r8169: a question of memory barrier in the r8169 driver | From | Jia-Ju Bai <> | Date | Fri, 19 Jan 2018 09:24:55 +0800 |
| |
On 2018/1/19 9:11, Francois Romieu wrote: > Jia-Ju Bai <baijiaju1990@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
| |