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Fri, 28 Jun 2019 10:24:05 -0700 (PDT) Date: Fri, 28 Jun 2019 19:23:51 +0200 From: Maciej Fijalkowski To: Ilias Apalodimas Cc: Jesper Dangaard Brouer , netdev@vger.kernel.org, jaswinder.singh@linaro.org, ard.biesheuvel@linaro.org, bjorn.topel@intel.com, magnus.karlsson@intel.com, daniel@iogearbox.net, ast@kernel.org, makita.toshiaki@lab.ntt.co.jp, jakub.kicinski@netronome.com, john.fastabend@gmail.com, davem@davemloft.net Subject: Re: [PATCH 3/3, net-next] net: netsec: add XDP support Message-ID: <20190628192351.00003555@gmail.com> In-Reply-To: <20190628164741.GA27936@apalos> References: <1561718355-13919-1-git-send-email-ilias.apalodimas@linaro.org> <1561718355-13919-4-git-send-email-ilias.apalodimas@linaro.org> <20190628153552.78a8c5ad@carbon> <20190628164741.GA27936@apalos> X-Mailer: Claws Mail 3.17.1 (GTK+ 2.24.32; x86_64-w64-mingw32) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Fri, 28 Jun 2019 19:47:41 +0300 Ilias Apalodimas wrote: > On Fri, Jun 28, 2019 at 03:35:52PM +0200, Jesper Dangaard Brouer wrote: > > On Fri, 28 Jun 2019 13:39:15 +0300 > > Ilias Apalodimas wrote: > > > > > +static int netsec_xdp_setup(struct netsec_priv *priv, struct bpf_prog *prog, > > > + struct netlink_ext_ack *extack) > > > +{ > > > + struct net_device *dev = priv->ndev; > > > + struct bpf_prog *old_prog; > > > + > > > + /* For now just support only the usual MTU sized frames */ > > > + if (prog && dev->mtu > 1500) { > > > + NL_SET_ERR_MSG_MOD(extack, "Jumbo frames not supported on XDP"); > > > + return -EOPNOTSUPP; > > > + } > > > + > > > + if (netif_running(dev)) > > > + netsec_netdev_stop(dev); > > > + > > > + /* Detach old prog, if any */ > > > + old_prog = xchg(&priv->xdp_prog, prog); > > > + if (old_prog) > > > + bpf_prog_put(old_prog); > > > + > > > + if (netif_running(dev)) > > > + netsec_netdev_open(dev); > > > > Shouldn't the if-statement be if (!netif_running(dev)) > > > > > + > This is there to restart the device if it's up already (to rebuild the rings). > This should be fine as-is I think that Jesper's concern was about that you could have already stopped the netdev earlier via netsec_netdev_stop (before the xchg)? So at this point __LINK_STATE_START might be not set. Maybe initially store what netif_running(dev) returns in stack variable and act on it, so your stop/open are symmetric? > > > > + return 0; > > > +} > > Thanks > /Ilias