From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Ira W. Snyder" Subject: Re: [PATCH 4/6] can: janz-ican3: fix support for CAN_RAW_RECV_OWN_MSGS Date: Thu, 19 Jul 2012 08:47:50 -0700 Message-ID: <20120719154750.GF25905@ovro.caltech.edu> References: <1342650798-2991-1-git-send-email-iws@ovro.caltech.edu> <1342650798-2991-5-git-send-email-iws@ovro.caltech.edu> <5007C66B.2020404@pengutronix.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from ovro.ovro.caltech.edu ([192.100.16.2]:53832 "EHLO ovro.ovro.caltech.edu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750852Ab2GSPrz (ORCPT ); Thu, 19 Jul 2012 11:47:55 -0400 Content-Disposition: inline In-Reply-To: <5007C66B.2020404@pengutronix.de> Sender: linux-can-owner@vger.kernel.org List-ID: To: Marc Kleine-Budde Cc: linux-can@vger.kernel.org On Thu, Jul 19, 2012 at 10:33:47AM +0200, Marc Kleine-Budde wrote: > On 07/19/2012 12:33 AM, Ira W. Snyder wrote: > > From: "Ira W. Snyder" > > > > The Janz VMOD-ICAN3 firmware does not support any sort of TX-done > > notification or interrupt. The driver previously used the hardware > > loopback to attempt to work around this deficiency, but this caused all > > sockets to receive all messages, even if CAN_RAW_RECV_OWN_MSGS is off. > > > > Using the new function ican3_cmp_echo_skb(), we can drop the loopback > > messages and return the original skbs. This fixes the issues with > > CAN_RAW_RECV_OWN_MSGS. > > > > A private skb queue is used to store the echo skbs. This avoids the need > > for any index management. > > > > Due to a lack of TX-error interrupts, bus errors are permanently > > enabled, and are used as a TX-error notification. This is used to drop > > an echo skb when transmission fails. Bus error packets are not generated > > if the user has not enabled bus error reporting. > > > > Signed-off-by: Ira W. Snyder > > Nitpicks inline, otherwise looks good. > > Marc > Thanks for the review. Another version of this patch with the nitpicks fixed will be posted in reply. > > --- > > drivers/net/can/janz-ican3.c | 199 ++++++++++++++++++++++++++++++++---------- > > 1 files changed, 154 insertions(+), 45 deletions(-) > > > > diff --git a/drivers/net/can/janz-ican3.c b/drivers/net/can/janz-ican3.c > > index d9d4ed1..1304712 100644 > > --- a/drivers/net/can/janz-ican3.c > > +++ b/drivers/net/can/janz-ican3.c > > @@ -220,6 +220,9 @@ struct ican3_dev { > > /* old and new style host interface */ > > unsigned int iftype; > > > > + /* queue for echo packets */ > > + struct sk_buff_head echoq; > > + > > /* > > * Any function which changes the current DPM page must hold this > > * lock while it is performing data accesses. This ensures that the > > @@ -924,7 +927,7 @@ static int ican3_handle_cevtind(struct ican3_dev *mod, struct ican3_msg *msg) > > struct net_device *dev = mod->ndev; > > struct net_device_stats *stats = &dev->stats; > > enum can_state state = mod->can.state; > > - u8 status, isrc, rxerr, txerr; > > + u8 isrc, ecc, status, rxerr, txerr; > > struct can_frame *cf; > > struct sk_buff *skb; > > > > @@ -940,15 +943,42 @@ static int ican3_handle_cevtind(struct ican3_dev *mod, struct ican3_msg *msg) > > return -EINVAL; > > } > > > > - skb = alloc_can_err_skb(dev, &cf); > > - if (skb == NULL) > > - return -ENOMEM; > > - > > isrc = msg->data[0]; > > + ecc = msg->data[2]; > > status = msg->data[3]; > > rxerr = msg->data[4]; > > txerr = msg->data[5]; > > > > + /* > > + * This hardware lacks any support other than bus error messages to > > + * determine if packet transmission has failed. > > + * > > + * When TX errors happen, one echo skb needs to be dropped from the > > + * front of the queue. > > + * > > + * A small bit of code is duplicated here and below, to avoid error > > + * skb allocation when it will just be freed immediately. > > + */ > > + if (isrc == CEVTIND_BEI) { > > + dev_dbg(mod->dev, "bus error interrupt, part 1\n"); > > nitpick: I would drop the ", part 1". > Agreed. > > + > > + /* TX error */ > > + if (!(ecc & ECC_DIR)) { > > + kfree_skb(skb_dequeue(&mod->echoq)); > > + stats->tx_errors++; > > + } else { > > + stats->rx_errors++; > > + } > > + > > + /* bus error reporting is off, return immediately */ > > + if (!(mod->can.ctrlmode & CAN_CTRLMODE_BERR_REPORTING)) > > + return 0; > > + } > > + > > + skb = alloc_can_err_skb(dev, &cf); > > + if (skb == NULL) > > + return -ENOMEM; > > + > > /* data overrun interrupt */ > > if (isrc == CEVTIND_DOI || isrc == CEVTIND_LOST) { > > dev_dbg(mod->dev, "data overrun interrupt\n"); > > @@ -976,9 +1006,8 @@ static int ican3_handle_cevtind(struct ican3_dev *mod, struct ican3_msg *msg) > > > > /* bus error interrupt */ > > if (isrc == CEVTIND_BEI) { > > - u8 ecc = msg->data[2]; > > + dev_dbg(mod->dev, "bus error interrupt, part 2\n"); > > > > - dev_dbg(mod->dev, "bus error interrupt\n"); > > I would remove the debug message here completely. > Agreed. > > mod->can.can_stats.bus_error++; > > cf->can_id |= CAN_ERR_PROT | CAN_ERR_BUSERROR; > > > > @@ -998,12 +1027,8 @@ static int ican3_handle_cevtind(struct ican3_dev *mod, struct ican3_msg *msg) > > break; > > } > > > > - if (!(ecc & ECC_DIR)) { > > + if (!(ecc & ECC_DIR)) > > cf->data[2] |= CAN_ERR_PROT_TX; > > - stats->tx_errors++; > > - } else { > > - stats->rx_errors++; > > - } > > > > cf->data[6] = txerr; > > cf->data[7] = rxerr; > > @@ -1088,6 +1113,85 @@ static void ican3_handle_message(struct ican3_dev *mod, struct ican3_msg *msg) > > } > > > > /* > > + * The ican3 needs to store all echo skbs, and therefore cannot > > + * use the generic infrastructure for this. > > + */ > > +static void ican3_put_echo_skb(struct ican3_dev *mod, struct sk_buff *skb) > > +{ > > + struct sock *srcsk = skb->sk; > > + > > + if (atomic_read(&skb->users) != 1) { > > + struct sk_buff *old_skb = skb; > > + > > + skb = skb_clone(old_skb, GFP_ATOMIC); > > + kfree_skb(old_skb); > > + if (!skb) > > + return; > > + } else { > > + skb_orphan(skb); > > + } > > + > > + skb->sk = srcsk; > > + > > + /* save this skb for tx interrupt echo handling */ > > + skb_queue_tail(&mod->echoq, skb); > > +} > > + > > +static unsigned int ican3_get_echo_skb(struct ican3_dev *mod) > > +{ > > + struct sk_buff *skb = skb_dequeue(&mod->echoq); > > + struct can_frame *cf; > > + u8 dlc; > > + > > + if (!skb) > > + return 0; > > Have you tested if this happens? It should now. Maybe add a netdev_err > or a pr_err_once here? > It doesn't happen. I've added a netdev_err(). > > + > > + cf = (struct can_frame *)skb->data; > > + dlc = cf->can_dlc; > > + > > + /* check flag whether this packet has to be looped back */ > > + if (skb->pkt_type != PACKET_LOOPBACK) { > > + kfree_skb(skb); > > + return dlc; > > + } > > + > > + skb->protocol = htons(ETH_P_CAN); > > + skb->pkt_type = PACKET_BROADCAST; > > + skb->ip_summed = CHECKSUM_UNNECESSARY; > > + skb->dev = mod->ndev; > > + netif_receive_skb(skb); > > + return dlc; > > +} > > + > > +/* > > + * Compare an skb with an existing echo skb > > + * > > + * This function will be used on devices which have a hardware loopback. > > + * On these devices, this function can be used to compare a received skb > > + * with the saved echo skbs so that the hardware echo skb can be dropped. > > + * > > + * Returns true if the skb's are identical, false otherwise. > > + */ > > +static bool ican3_echo_skb_matches(struct ican3_dev *mod, struct sk_buff *skb) > > +{ > > + struct can_frame *cf = (struct can_frame *)skb->data; > > + struct sk_buff *echo_skb = skb_peek(&mod->echoq); > > + struct can_frame *echo_cf; > > + > > + if (!echo_skb) > > + return false; > > + > > + echo_cf = (struct can_frame *)echo_skb->data; > > + if (cf->can_id != echo_cf->can_id) > > + return false; > > + > > + if (cf->can_dlc != echo_cf->can_dlc) > > + return false; > > + > > + return memcmp(cf->data, echo_cf->data, cf->can_dlc) == 0; > > +} > > + > > +/* > > * Check that there is room in the TX ring to transmit another skb > > * > > * LOCKING: must hold mod->lock > > @@ -1097,6 +1201,10 @@ static bool ican3_txok(struct ican3_dev *mod) > > struct ican3_fast_desc __iomem *desc; > > u8 control; > > > > + /* check that we have echo queue space */ > > + if (skb_queue_len(&mod->echoq) >= ICAN3_TX_BUFFERS) > > + return false; > > + > > /* copy the control bits of the descriptor */ > > ican3_set_page(mod, mod->fasttx_start + (mod->fasttx_num / 16)); > > desc = mod->dpm + ((mod->fasttx_num % 16) * sizeof(*desc)); > > @@ -1147,10 +1255,27 @@ static int ican3_recv_skb(struct ican3_dev *mod) > > /* convert the ICAN3 frame into Linux CAN format */ > > ican3_to_can_frame(mod, &desc, cf); > > > > - /* receive the skb, update statistics */ > > - netif_receive_skb(skb); > > + /* > > + * If this is an ECHO frame received from the hardware loopback > > + * feature, use the skb saved in the ECHO stack instead. This allows > > + * the Linux CAN core to support CAN_RAW_RECV_OWN_MSGS correctly. > > + * > > + * Since this is a confirmation of a successfully transmitted packet > > + * sent from this host, update the transmit statistics. > > + * > > + * Also, the netdevice queue needs to be allowed to send packets again. > > + */ > > + if (ican3_echo_skb_matches(mod, skb)) { > > + stats->tx_packets++; > > + stats->tx_bytes += ican3_get_echo_skb(mod); > > + kfree_skb(skb); > > + goto err_noalloc; > > + } > > + > > + /* update statistics, receive the skb */ > > stats->rx_packets++; > > stats->rx_bytes += cf->can_dlc; > > + netif_receive_skb(skb); > > > > err_noalloc: > > /* toggle the valid bit and return the descriptor to the ring */ > > @@ -1173,13 +1298,13 @@ err_noalloc: > > static int ican3_napi(struct napi_struct *napi, int budget) > > { > > struct ican3_dev *mod = container_of(napi, struct ican3_dev, napi); > > - struct ican3_msg msg; > > unsigned long flags; > > int received = 0; > > int ret; > > > > /* process all communication messages */ > > while (true) { > > + struct ican3_msg msg; > > ret = ican3_recv_msg(mod, &msg); > > if (ret) > > break; > > @@ -1351,7 +1476,6 @@ static int __devinit ican3_startup_module(struct ican3_dev *mod) > > static int ican3_open(struct net_device *ndev) > > { > > struct ican3_dev *mod = netdev_priv(ndev); > > - u8 quota; > > int ret; > > > > /* open the CAN layer */ > > @@ -1361,19 +1485,6 @@ static int ican3_open(struct net_device *ndev) > > return ret; > > } > > > > - /* set the bus error generation state appropriately */ > > - if (mod->can.ctrlmode & CAN_CTRLMODE_BERR_REPORTING) > > - quota = ICAN3_BUSERR_QUOTA_MAX; > > - else > > - quota = 0; > > - > > - ret = ican3_set_buserror(mod, quota); > > - if (ret) { > > - dev_err(mod->dev, "unable to set bus-error\n"); > > - close_candev(ndev); > > - return ret; > > - } > > - > > /* bring the bus online */ > > ret = ican3_set_bus_state(mod, true); > > if (ret) { > > @@ -1405,6 +1516,9 @@ static int ican3_stop(struct net_device *ndev) > > return ret; > > } > > > > + /* drop all outstanding echo skbs */ > > + skb_queue_purge(&mod->echoq); > > + > > /* close the CAN layer */ > > close_candev(ndev); > > return 0; > > @@ -1413,7 +1527,6 @@ static int ican3_stop(struct net_device *ndev) > > static int ican3_xmit(struct sk_buff *skb, struct net_device *ndev) > > { > > struct ican3_dev *mod = netdev_priv(ndev); > > - struct net_device_stats *stats = &ndev->stats; > > struct can_frame *cf = (struct can_frame *)skb->data; > > struct ican3_fast_desc desc; > > void __iomem *desc_addr; > > @@ -1426,8 +1539,7 @@ static int ican3_xmit(struct sk_buff *skb, struct net_device *ndev) > > > > /* check that we can actually transmit */ > > if (!ican3_txok(mod)) { > > - dev_err(mod->dev, "no free descriptors, stopping queue\n"); > > - netif_stop_queue(ndev); > > + dev_err(mod->dev, "BUG: no free descriptors\n"); > > spin_unlock_irqrestore(&mod->lock, flags); > > return NETDEV_TX_BUSY; > > } > > @@ -1442,6 +1554,14 @@ static int ican3_xmit(struct sk_buff *skb, struct net_device *ndev) > > can_frame_to_ican3(mod, cf, &desc); > > > > /* > > + * This hardware doesn't have TX-done notifications, so we'll try and > > + * emulate it the best we can using ECHO skbs. Add the skb to the ECHO > > + * stack. Upon packet reception, check if the ECHO skb and received > > + * skb match, and use that to wake the queue. > > + */ > > + ican3_put_echo_skb(mod, skb); > > + > > + /* > > * the programming manual says that you must set the IVALID bit, then > > * interrupt, then set the valid bit. Quite weird, but it seems to be > > * required for this to work > > @@ -1459,19 +1579,7 @@ static int ican3_xmit(struct sk_buff *skb, struct net_device *ndev) > > mod->fasttx_num = (desc.control & DESC_WRAP) ? 0 > > : (mod->fasttx_num + 1); > > > > - /* update statistics */ > > - stats->tx_packets++; > > - stats->tx_bytes += cf->can_dlc; > > - kfree_skb(skb); > > - > > - /* > > - * This hardware doesn't have TX-done notifications, so we'll try and > > - * emulate it the best we can using ECHO skbs. Get the next TX > > - * descriptor, and see if we have room to send. If not, stop the queue. > > - * It will be woken when the ECHO skb for the current packet is recv'd. > > - */ > > - > > - /* copy the control bits of the descriptor */ > > + /* if there is no free descriptor space, stop the transmit queue */ > > if (!ican3_txok(mod)) > > netif_stop_queue(ndev); > > > > @@ -1667,6 +1775,7 @@ static int __devinit ican3_probe(struct platform_device *pdev) > > mod->dev = &pdev->dev; > > mod->num = pdata->modno; > > netif_napi_add(ndev, &mod->napi, ican3_napi, ICAN3_RX_BUFFERS); > > + skb_queue_head_init(&mod->echoq); > > spin_lock_init(&mod->lock); > > init_completion(&mod->termination_comp); > > init_completion(&mod->buserror_comp); > > > -- > Pengutronix e.K. | Marc Kleine-Budde | > Industrial Linux Solutions | Phone: +49-231-2826-924 | > Vertretung West/Dortmund | Fax: +49-5121-206917-5555 | > Amtsgericht Hildesheim, HRA 2686 | http://www.pengutronix.de | >