netdev - RE: [PATCH net v2 1/2] Revert "r8152: napi hangup fix after disconnect"

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Date:   Mon, 26 Aug 2019 09:43:32 +0000
From:   Hayes Wang <hayeswang@...ltek.com>
To:     Jiri Slaby <jslaby@...e.cz>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>
CC:     nic_swsd <nic_swsd@...ltek.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: RE: [PATCH net v2 1/2] Revert "r8152: napi hangup fix after disconnect"

Jiri Slaby [mailto:jslaby@...e.cz]
> Sent: Monday, August 26, 2019 4:55 PM
[...]
> Could you clarify *why* it conflicts? And how is the problem fixed by
> 0ee1f473496 avoided now?

In rtl8152_disconnect(), the flow would be as following.

static void rtl8152_disconnect(struct usb_interface *intf)
{
	...
	- netif_napi_del(&tp->napi);
	- unregister_netdev(tp->netdev);
	   - rtl8152_close
	      - napi_disable

Therefore you add a checking of RTL8152_UNPLUG to avoid
calling napi_disable() after netif_napi_del(). However,
after commit ffa9fec30ca0 ("r8152: set RTL8152_UNPLUG
only for real disconnection"), RTL8152_UNPLUG is not
always set when calling rtl8152_disconnect(). That is,
napi_disable() would be called after netif_napi_del(),
if RTL8152_UNPLUG is not set.

The best way is to avoid calling netif_napi_del() before
calling unregister_netdev(). And I has submitted such
patch following this one.

Best Regards,
Hayes