Jia-Ju Bai :
>
> On 2018/1/19 9:11, Francois Romieu wrote:
> > Jia-Ju Bai :
> > [...]
> > > 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 Rin
Peter Zijlstra :
> On Fri, Jan 19, 2018 at 02:11:18AM +0100, Francois Romieu wrote:
> > Peter Zijlstra :
> > [...]
> > > There is only 1 variable afaict. Memory barriers need at least 2 in
> > > order to be able to do _anything_.
> >
> > I don't get your point: why don't {cur_tx, dirty_tx} quali
On Fri, Jan 19, 2018 at 02:11:18AM +0100, Francois Romieu wrote:
> Peter Zijlstra :
> [...]
> > There is only 1 variable afaict. Memory barriers need at least 2 in
> > order to be able to do _anything_.
>
> I don't get your point: why don't {cur_tx, dirty_tx} qualify as said
> two variables ?
Th
On 2018/1/19 9:11, Francois Romieu wrote:
Jia-Ju Bai :
[...]
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");
go
Jia-Ju Bai :
[...]
> 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
Peter Zijlstra :
[...]
> There is only 1 variable afaict. Memory barriers need at least 2 in
> order to be able to do _anything_.
I don't get your point: why don't {cur_tx, dirty_tx} qualify as said
two variables ?
--
Ueimor
On Thu, Jan 18, 2018 at 10:06:17PM +0800, Jia-Ju Bai wrote:
> In the rt8169 driver, the function "rtl_tx" uses "smp_mb" to sync the
> writing operation with rtl8169_start_xmit:
> if (tp->dirty_tx != dirty_tx) {
> tp->dirty_tx = dirty_tx;
> smp_mb();
> ...
> }
> The f
In the rt8169 driver, the function "rtl_tx" uses "smp_mb" to sync the
writing operation with rtl8169_start_xmit:
if (tp->dirty_tx != dirty_tx) {
tp->dirty_tx = dirty_tx;
smp_mb();
...
}
The function rtl8169_start_xmit reads tp->dirty_tx in TX_FRAGS_READY_FOR:
i
