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

From: Pavel Machek
Date: Mon Dec 05 2016 - 17:10:13 EST


Hi!

> >
> > Actually, I was wrong. irqlock protection is needed, since
> > stmmac_tx_clean() is called from timer, and that's interrupt context,
> > as you can confirm using BUG_ON(in_interrupt());
> >
>
> in_interrupt() can mean both softirq and hardirq context. In this case it
> means softirq. So I guess you were right before, and no irq locking is needed.

Are you absolutely sure? Because my testing seems to indicate
otherwise (but I may have made a mistake).

According to

https://www.kernel.org/pub/linux/kernel/people/rusty/kernel-locking/c214.html

we need spin_lock_bh at minimum, as we are locking user context
against timer.

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

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