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[91.181.7.168]) by smtp.gmail.com with ESMTPSA id h8sm2351459ejj.22.2021.06.11.10.54.50 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 11 Jun 2021 10:54:51 -0700 (PDT) Date: Fri, 11 Jun 2021 19:54:49 +0200 From: Ben Hutchings To: Grygorii Strashko Cc: "David S. Miller" , netdev@vger.kernel.org, Jakub Kicinski , linux-kernel@vger.kernel.org, Vignesh Raghavendra , linux-omap@vger.kernel.org, Lokesh Vutla , stable@vger.kernel.org Subject: Re: [PATCH net] net: ethernet: ti: cpsw: fix min eth packet size for non-switch use-cases Message-ID: <20210611175448.GA25728@cephalopod> References: <20210611132732.10690-1-grygorii.strashko@ti.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210611132732.10690-1-grygorii.strashko@ti.com> User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org On Fri, Jun 11, 2021 at 04:27:32PM +0300, Grygorii Strashko wrote: [...] > --- a/drivers/net/ethernet/ti/cpsw_new.c > +++ b/drivers/net/ethernet/ti/cpsw_new.c > @@ -918,14 +918,17 @@ static netdev_tx_t cpsw_ndo_start_xmit(struct sk_buff *skb, > struct cpts *cpts = cpsw->cpts; > struct netdev_queue *txq; > struct cpdma_chan *txch; > + unsigned int len; > int ret, q_idx; > > - if (skb_padto(skb, CPSW_MIN_PACKET_SIZE)) { > + if (skb_padto(skb, priv->tx_packet_min)) { > cpsw_err(priv, tx_err, "packet pad failed\n"); > ndev->stats.tx_dropped++; > return NET_XMIT_DROP; > } > > + len = skb->len < priv->tx_packet_min ? priv->tx_packet_min : skb->len; > + > if (skb_shinfo(skb)->tx_flags & SKBTX_HW_TSTAMP && > priv->tx_ts_enabled && cpts_can_timestamp(cpts, skb)) > skb_shinfo(skb)->tx_flags |= SKBTX_IN_PROGRESS; > @@ -937,7 +940,7 @@ static netdev_tx_t cpsw_ndo_start_xmit(struct sk_buff *skb, > txch = cpsw->txv[q_idx].ch; > txq = netdev_get_tx_queue(ndev, q_idx); > skb_tx_timestamp(skb); > - ret = cpdma_chan_submit(txch, skb, skb->data, skb->len, > + ret = cpdma_chan_submit(txch, skb, skb->data, len, > priv->emac_port); > if (unlikely(ret != 0)) { > cpsw_err(priv, tx_err, "desc submit failed\n"); This change is odd because cpdma_chan_submit() already pads the DMA length. Would it not make more sense to update cpdma_params::min_packet_size instead of adding a second minimum? [...] > @@ -1686,6 +1690,7 @@ static int cpsw_dl_switch_mode_set(struct devlink *dl, u32 id, > > priv = netdev_priv(sl_ndev); > slave->port_vlan = vlan; > + priv->tx_packet_min = CPSW_MIN_PACKET_SIZE_VLAN; > if (netif_running(sl_ndev)) > cpsw_port_add_switch_def_ale_entries(priv, > slave); > @@ -1714,6 +1719,7 @@ static int cpsw_dl_switch_mode_set(struct devlink *dl, u32 id, > > priv = netdev_priv(slave->ndev); > slave->port_vlan = slave->data->dual_emac_res_vlan; > + priv->tx_packet_min = CPSW_MIN_PACKET_SIZE; > cpsw_port_add_dual_emac_def_ale_entries(priv, slave); > } > [...] What happens if this races with the TX path? Should there be a netif_tx_lock() / netif_tx_unlock() around this change? Ben.