linux-kernel - Re: [PATCH net v2 1/2] Revert "r8152: napi hangup fix after disconnect"

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Message-Id: <20190826.135549.1075785443210666224.davem@davemloft.net>
Date:   Mon, 26 Aug 2019 13:55:49 -0700 (PDT)
From:   David Miller <davem@...emloft.net>
To:     hayeswang@...ltek.com
Cc:     jslaby@...e.cz, netdev@...r.kernel.org, nic_swsd@...ltek.com,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH net v2 1/2] Revert "r8152: napi hangup fix after
 disconnect"

From: Hayes Wang <hayeswang@...ltek.com>
Date: Mon, 26 Aug 2019 09:43:32 +0000

> 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.

These details belong in the commit message, always.