Re: [PATCH net-next 2/2] r8152: check the status before submittingrx

From: Hayes Wang <redacted>
Date: Mon, 22 Dec 2014 02:53:42 +0000

 David Miller [mailto:davem@davemloft.net] 

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Sent: Saturday, December 20, 2014 4:44 AM

[...]

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Don't submit the rx if the device is unplugged, linking down,
or stopped.

 ...

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@@ -1789,6 +1789,11 @@ int r8152_submit_rx(struct r8152 

*tp, struct rx_agg *agg, gfp_t mem_flags)

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 {
 	int ret;
 
+	/* The rx would be stopped, so skip submitting */
+	if (test_bit(RTL8152_UNPLUG, &tp->flags) ||
+	    !test_bit(WORK_ENABLE, &tp->flags) || !(tp->speed & LINK_STATUS))
+		return 0;
+

I think netif_carrier_off() should always be true in all three of those
situations, and would be a much simpler test than what you've coded
here.

When the device is unplugged or stopped, the linking status
may be true, so I add additional checks to avoid the submission.

Besides, in set_carrier() I set netif_carrier_on() after
ops.enable() to avoid any transmission before I finish
starting the tx/rx.

	tp->rtl_ops.enable(tp);
	set_bit(RTL8152_SET_RX_MODE, &tp->flags);
	netif_carrier_on(netdev);

However, the r8152_submit_rx() would be called in ops.enable(),
and the check of netif_carrier_ok() would be always false. That
is why I use tp->speed, not netif_carrier_ok(), to check the
linking stauts.

I stil think your check is way too complicated for this fast path so I
would ask that you arrange things such that the simpler
netif_carrier_off() test works.

Especially because that is what the core networking stack uses
to decide whether to send packets to us as well.