From mboxrd@z Thu Jan  1 00:00:00 1970
From: "Jon Rosen (jrosen)" <jrosen@cisco.com>
Subject: RE: [PATCH v2] packet: track ring entry use using a shadow ring to
 prevent RX ring overrun
Date: Wed, 23 May 2018 11:08:33 +0000
Message-ID: <e942c1bbe48b451b92620396746986ab@XCH-RTP-016.cisco.com>
References: <1526731655-10087-1-git-send-email-jrosen@cisco.com>
 <CAF=yD-+kjceErK=CApiu1oY9uTjVWG2qeX=NkGVYufVVC_L2PA@mail.gmail.com>
 <CAF=yD-KvTyTibhqpKP79Obfk8KRVDLMyb6THNwNgrJzs47bAtQ@mail.gmail.com>
 <b7f6cc54a9f04132a279b15de0187ddd@XCH-RTP-016.cisco.com>
 <CAF=yD-Kfto4jJYMFzn=PV8OYdhEmdNfW+aakDhRMzRBWhWY0UQ@mail.gmail.com>
 <64c91d04479348cabbcdf1df0ff7d40f@XCH-RTP-016.cisco.com>
 <CAF=yD-KHFwhVt4xzED7FPLd_xej9nLmoZOgZG0PmsVgbrnN0Ng@mail.gmail.com>
Mime-Version: 1.0
Content-Type: text/plain; charset="utf-8"
Content-Transfer-Encoding: base64
Cc: "David S. Miller" <davem@davemloft.net>,
        Willem de Bruijn <willemb@google.com>,
        Eric Dumazet <edumazet@google.com>,
        Kees Cook <keescook@chromium.org>,
        David Windsor <dwindsor@gmail.com>,
        "Rosen, Rami" <rami.rosen@intel.com>,
        "Reshetova, Elena" <elena.reshetova@intel.com>,
        "Mike Maloney" <maloney@google.com>,
        Benjamin Poirier <bpoirier@suse.com>,
        "Thomas Gleixner" <tglx@linutronix.de>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        "open list:NETWORKING [GENERAL]" <netdev@vger.kernel.org>,
        open list <linux-kernel@vger.kernel.org>
To: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
Return-path: <linux-kernel-owner@vger.kernel.org>
In-Reply-To: <CAF=yD-KHFwhVt4xzED7FPLd_xej9nLmoZOgZG0PmsVgbrnN0Ng@mail.gmail.com>
Content-Language: en-US
Sender: linux-kernel-owner@vger.kernel.org
List-Id: netdev.vger.kernel.org
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