netdev - Re: [net-next v1 PATCH 3/4] page_pool: block alloc cache during shutdown

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Date:   Sat, 16 Nov 2019 11:47:07 +0100
From:   Jesper Dangaard Brouer <brouer@...hat.com>
To:     "Jonathan Lemon" <jonathan.lemon@...il.com>
Cc:     "Toke Høiland-Jørgensen" <toke@...hat.com>,
        netdev@...r.kernel.org,
        "Ilias Apalodimas" <ilias.apalodimas@...aro.org>,
        "Saeed Mahameed" <saeedm@...lanox.com>,
        "Matteo Croce" <mcroce@...hat.com>,
        "Lorenzo Bianconi" <lorenzo@...nel.org>,
        "Tariq Toukan" <tariqt@...lanox.com>, brouer@...hat.com
Subject: Re: [net-next v1 PATCH 3/4] page_pool: block alloc cache during
 shutdown

On Fri, 15 Nov 2019 10:38:21 -0800
"Jonathan Lemon" <jonathan.lemon@...il.com> wrote:

> Case 1:
> Now, if the driver screws up and tries to re-use the pool and allocate
> another packet, it enters __page_pool_get_cached(), which will decrement
> the alloc.count, and return NULL.  This causes a fallback to
> __get_alloc_pages_slow(), which bumps up the pool inflight count.

I can see that I made a mistake, and cannot use NULL as the poison
value. Let me drop this patch, so others (and yours) can go in before
merge window.

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