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Subject: Re: inconsistent lock state with usbnet/asix usb ethernet and xhci
From:   Oliver Neukum <oneukum@suse.com>
To:     Eric Dumazet <eric.dumazet@gmail.com>,
        Marek Szyprowski <m.szyprowski@samsung.com>,
        LKML <linux-kernel@vger.kernel.org>,
        'Linux Samsung SOC' <linux-samsung-soc@vger.kernel.org>,
        Linux USB Mailing List <linux-usb@vger.kernel.org>,
        netdev@vger.kernel.org
Cc:     Dean Jenkins <Dean_Jenkins@mentor.com>
Date:   Tue, 27 Feb 2018 17:07:55 +0100
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Am Dienstag, den 27.02.2018, 07:13 -0800 schrieb Eric Dumazet:
> On Tue, 2018-02-27 at 07:09 -0800, Eric Dumazet wrote:
> > 
> > 
> > Note that for this one, it seems we also could perform stats updates in
> > BH context, since skb is queued via defer_bh()
> > 
> > But simplicity wins I guess.
> 
> Thinking more about this, I am not sure we have any guarantee that TX
> and RX can not run on multiple cpus.
> 
> Using an unique syncp is not going to be safe, even if we make lockdep
> happy enough with the local_irq save/restore.

Unfortunately you are right. It is not guaranteed for some hardware.

	Regards
		Oliver