Subject: Re: netif_receive_skb_list and interrupts enabled/disabled

From: Jesper Dangaard Brouer <[email-masked]>
Date: Wed, 27 Mar 2019 09:20:11 +0100

On Tue, 26 Mar 2019 21:04:09 +0100
Heiner Kallweit <[email-masked]> wrote:

> A question inspired by 0a25d92c6f4f ("dpaa2-eth: use netif_receive_skb_list"):
> kerneldoc of netif_receive_skb_list states that interrupts should be
> enabled. 

Do notice that the exact same comment (and rule) applies to
netif_receive_skb() which also have below comment:

/* [...]
 * This function may only be called from softirq context and interrupts
 * should be enabled.
 */

> When used from NAPI context irqs typically are disabled.
> And if the NAPI budget is fully consumed then interrupts don't get enabled
> in the same NAPI poll loop. How is this supposed to play together?

You have misunderstood that is means that interrupts should be
enabled.  It is talking about local_irq_disable/enable and
local_irq_save/restore.  This is different from disabling the IRQs on a
given NIC RX-queue.

-- 
Best regards,
  Jesper Dangaard Brouer
  MSc.CS, Principal Kernel Engineer at Red Hat
  LinkedIn: http://www.linkedin.com/in/brouer