From mboxrd@z Thu Jan  1 00:00:00 1970
From: Stephen Hemminger <stephen@networkplumber.org>
Subject: Re: [PATCH] The VMXNET3 PMD can't receive packet
 suddenly after a lot of traffic coming in. The root cause is due to mbuf
 allocation fail in vmxnet3_post_rx_bufs() and there is no error handling
 when it is called from vmxnet3_recv_pkts(). Th...
Date: Thu, 23 Jul 2015 09:45:33 -0700
Message-ID: <20150723094533.71c3dc97@urahara>
References: <1437616135-5364-1-git-send-email-mac_leehk@yahoo.com.hk>
 <20150722222731.497b2abc@uryu.home.lan>
 <98DB008FA2AC6644B40AD8C766FAB271020CB2EC2B@BOREAL.arubanetworks.com>
Mime-Version: 1.0
Content-Type: text/plain; charset=US-ASCII
Content-Transfer-Encoding: 7bit
Cc: "dev@dpdk.org" <dev@dpdk.org>,
 "mac_leehk@yahoo.com.hk" <mac_leehk@yahoo.com.hk>
To: Vithal S Mohare <vmohare@arubanetworks.com>
Return-path: <dev-bounces@dpdk.org>
Received: from mail-pa0-f41.google.com (mail-pa0-f41.google.com
 [209.85.220.41]) by dpdk.org (Postfix) with ESMTP id 40F33C3A8
 for <dev@dpdk.org>; Thu, 23 Jul 2015 18:45:37 +0200 (CEST)
Received: by padck2 with SMTP id ck2so159835281pad.0
 for <dev@dpdk.org>; Thu, 23 Jul 2015 09:45:36 -0700 (PDT)
In-Reply-To: <98DB008FA2AC6644B40AD8C766FAB271020CB2EC2B@BOREAL.arubanetworks.com>
List-Id: patches and discussions about DPDK <dev.dpdk.org>
List-Unsubscribe: <http://dpdk.org/ml/options/dev>,
 <mailto:dev-request@dpdk.org?subject=unsubscribe>
List-Archive: <http://dpdk.org/ml/archives/dev/>
List-Post: <mailto:dev@dpdk.org>
List-Help: <mailto:dev-request@dpdk.org?subject=help>
List-Subscribe: <http://dpdk.org/ml/listinfo/dev>,
 <mailto:dev-request@dpdk.org?subject=subscribe>
Errors-To: dev-bounces@dpdk.org
Sender: "dev" <dev-bounces@dpdk.org>

On Thu, 23 Jul 2015 07:31:01 +0000
Vithal S Mohare <vmohare@arubanetworks.com> wrote:

> +    /* VMXNET3
> +     * In the above loop, vmxnet3_post_rx_bufs would fai if all the mbufs currently allocated.
> +     * In such scenarios where hw device hasn't left with any of 'rx' descriptors, packets from
> +     * network will not be 'DMA'd to driver.  While the only way to refresh 'rxd' back to hw is
> +     * though above i.e. when packet is received from hw.  So, there is potential dead-lock.
> +     *
> +     * Now, to break the deadlock, vmxnet3_post_rx_bufs() is triggered below when the poll 
> +     * goes empty 'rcd'.  vmxnet3_post_rx_bufs() is no-op if all the descriptors are allocated
> +     * in hw
> +     */

This is the kind of thing which should be in the git change log
description not the code. Comments like this are too wordy and get out
of date.