Re: [PATCH v2 net] net: rps: fix cpu unplug

[David Miller <davem@davemloft.net>]

From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Thu, 15 Jan 2015 17:04:22 -0800

> From: Eric Dumazet <edumazet@google.com>
> 
> softnet_data.input_pkt_queue is protected by a spinlock that
> we must hold when transferring packets from victim queue to an active
> one. This is because other cpus could still be trying to enqueue packets
> into victim queue.
> 
> A second problem is that when we transfert the NAPI poll_list from
> victim to current cpu, we absolutely need to special case the percpu
> backlog, because we do not want to add complex locking to protect
> process_queue : Only owner cpu is allowed to manipulate it, unless cpu
> is offline.
> 
> Based on initial patch from Prasad Sodagudi & Subash Abhinov
> Kasiviswanathan.
> 
> This version is better because we do not slow down packet processing,
> only make migration safer.
> 
> Reported-by: Prasad Sodagudi <psodagud@codeaurora.org>
> Reported-by: Subash Abhinov Kasiviswanathan <subashab@codeaurora.org>
> Signed-off-by: Eric Dumazet <edumazet@google.com>

Applied and queued up for -stable, thanks Eric.