Messages in this thread | | | Date | Fri, 19 Jan 2018 02:11:01 +0100 | From | Francois Romieu <> | Subject | Re: net: r8169: a question of memory barrier in the r8169 driver |
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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.
-- Ueimor
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