linux-kernel - Re: stmmac ethernet in kernel 4.9-rc6: coalescing related pauses.

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Message-ID: <20161205224057.GB19135@amd>
Date:   Mon, 5 Dec 2016 23:40:57 +0100
From:   Pavel Machek <pavel@....cz>
To:     Lino Sanfilippo <LinoSanfilippo@....de>
Cc:     Giuseppe CAVALLARO <peppe.cavallaro@...com>,
        alexandre.torgue@...com, David Miller <davem@...emloft.net>,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: stmmac ethernet in kernel 4.9-rc6: coalescing related pauses.

On Mon 2016-12-05 23:37:09, Lino Sanfilippo wrote:
> Hi Pavel,
> 
> On 05.12.2016 23:02, Pavel Machek wrote:
> > 
> > we need spin_lock_bh at minimum, as we are locking user context
> > against timer.
> > 
> > Best regards,
> > 									Pavel
> > 
> 
> I was referring to stmmac_tx_clean() which AFAICS is only called from softirq context,
> (one time in the timer handler and one time in napi poll handler) so a spin_lock() should
> be sufficient. I cant see how this is called from userspace. If it were, a spin_lock_bh() had
> to be used, of course.

stmmac_tx_clean() shares lock with stmmac_tx() -- and that's process
context as far as I can tell. So... spin_lock_bh() at
minimum... right?

									Pavel

-- 
(english) http://www.livejournal.com/~pavelmachek
(cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html

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