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From: Stephen Hemminger <stephen@networkplumber.org>
To: longli@linuxonhyperv.com
Cc: Stephen Hemminger <sthemmin@microsoft.com>,
	dev@dpdk.org, Long Li <longli@microsoft.com>
Subject: Re: [dpdk-dev] [PATCH 1/2] net/netvsc: fix underflow error when external mbuf are used in the receive path
Date: Wed, 1 Jul 2020 17:06:46 -0700	[thread overview]
Message-ID: <20200701170646.0690c90e@hermes.lan> (raw)
In-Reply-To: <1592961106-82820-1-git-send-email-longli@linuxonhyperv.com>

On Tue, 23 Jun 2020 18:11:45 -0700
longli@linuxonhyperv.com wrote:

> From: Long Li <longli@microsoft.com>
> 
> When rte_pktmbuf_attach_extbuf() is used, the driver should not decrease the
> reference count in its callback function hn_rx_buf_free_cb, because the
> reference count is already decreased by rte_pktmbuf. Doing it twice may result
> in underflow and driver may never send an ack packet over vmbus to host.
> 
> Also declares rxbuf_outstanding as atomic, because this value is shared
> among all receive queues.
> 
> Signed-off-by: Long Li <longli@microsoft.com>

Good catch. DPDK ought to have a real refcnt type like the kernel.
One that traps on underflow.

Acked-by: Stephen Hemminger <stephen@networkplumber.org>

  parent reply	other threads:[~2020-07-02  0:06 UTC|newest]

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2020-06-24  1:11 longli
2020-06-24  1:11 ` [dpdk-dev] [PATCH 2/2] net/netvsc: detach external buffer on failure longli
2020-07-02  0:05   ` Stephen Hemminger
2020-07-02  0:06 ` Stephen Hemminger [this message]
2020-07-09 15:28   ` [dpdk-dev] [PATCH 1/2] net/netvsc: fix underflow error when external mbuf are used in the receive path Ferruh Yigit

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