From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jarek Poplawski Subject: Re: [PATCH] sky2: safer transmit ring cleaning (v4) Date: Thu, 14 Jan 2010 10:14:45 +0000 Message-ID: <20100114101445.GA7210@ff.dom.local> References: <20100112085633.GB6628@ff.dom.local> <20100112.014218.112731835.davem@davemloft.net> <20100112.025620.210305029.davem@davemloft.net> <20100112081513.0175d579@nehalam> <4B4CC0E3.5050106@majjas.com> <4B4CC29E.4020703@majjas.com> <4B4CDC28.2050508@majjas.com> <20100112201012.21894fd3@nehalam> <4B4DEEF9.7020806@majjas.com> <20100113194148.139091a3@nehalam> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Michael Breuer , David Miller , mikem@ring3k.org, flyboy@gmail.com, rjw@sisk.pl, netdev@vger.kernel.org To: Stephen Hemminger Return-path: Received: from mail-fx0-f225.google.com ([209.85.220.225]:55955 "EHLO mail-fx0-f225.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754666Ab0ANKOx (ORCPT ); Thu, 14 Jan 2010 05:14:53 -0500 Received: by fxm25 with SMTP id 25so307337fxm.21 for ; Thu, 14 Jan 2010 02:14:51 -0800 (PST) Content-Disposition: inline In-Reply-To: <20100113194148.139091a3@nehalam> Sender: netdev-owner@vger.kernel.org List-ID: On Wed, Jan 13, 2010 at 07:41:48PM -0800, Stephen Hemminger wrote: > Subject: sky2: safer transmit cleanup > > This code makes transmit path and transmit reset safer by: > * adding memory barrier before checking available ring slots > * reseting state of tx ring elements after free > * seperate cleanup function from ring done function > * removing mostly unused tx_next element > * ignoring transmit completion if device is offline > > Signed-off-by: Stephen Hemminger > > --- > This patch is against the current net-next-2.6 tree. > This version handles the case of dual port shared transmit status > and other cases where it is possible for tx_done to be called when > device is being changed. > > --- a/drivers/net/sky2.c 2010-01-13 08:32:51.360161158 -0800 > +++ b/drivers/net/sky2.c 2010-01-13 08:35:37.685531490 -0800 > @@ -1596,6 +1596,9 @@ static inline int tx_inuse(const struct > /* Number of list elements available for next tx */ > static inline int tx_avail(const struct sky2_port *sky2) > { > + /* Makes sure update of tx_prod from start_xmit and > + tx_cons from tx_done are seen. */ > + smp_mb(); > return sky2->tx_pending - tx_inuse(sky2); > } > > @@ -1618,8 +1621,7 @@ static unsigned tx_le_req(const struct s > return count; > } > > -static void sky2_tx_unmap(struct pci_dev *pdev, > - const struct tx_ring_info *re) > +static void sky2_tx_unmap(struct pci_dev *pdev, struct tx_ring_info *re) > { > if (re->flags & TX_MAP_SINGLE) > pci_unmap_single(pdev, pci_unmap_addr(re, mapaddr), > @@ -1629,6 +1631,7 @@ static void sky2_tx_unmap(struct pci_dev > pci_unmap_page(pdev, pci_unmap_addr(re, mapaddr), > pci_unmap_len(re, maplen), > PCI_DMA_TODEVICE); > + re->flags = 0; > } > > /* > @@ -1804,7 +1807,8 @@ mapping_error: > } > > /* > - * Free ring elements from starting at tx_cons until "done" > + * Transmit complete processing > + * Free ring elements from starting at tx_cons until done index > * > * NB: > * 1. The hardware will tell us about partial completion of multi-part > @@ -1813,11 +1817,14 @@ mapping_error: > * looks at the tail of the queue of FIFO (tx_cons), not > * the head (tx_prod) > */ > -static void sky2_tx_complete(struct sky2_port *sky2, u16 done) > +static void sky2_tx_done(struct net_device *dev, u16 done) > { > - struct net_device *dev = sky2->netdev; > + struct sky2_port *sky2 = netdev_priv(dev); > unsigned idx; > > + if (!(netif_running(dev) & netif_device_present(dev))) This makes it safe, but it still resembles the "short term fix" according do David's opinion. This change seems to affect dev->stats too. Since they are not updated in sky2_tx_clean(). Btw, I hope "&" is some optimization because it's less readable than "&&". Jarek P. > + return; > + > BUG_ON(done >= sky2->tx_ring_size); > > for (idx = sky2->tx_cons; idx != done; > @@ -1828,6 +1835,8 @@ static void sky2_tx_complete(struct sky2 > sky2_tx_unmap(sky2->hw->pdev, re); > > if (skb) { > + re->skb = NULL; > + > if (unlikely(netif_msg_tx_done(sky2))) > printk(KERN_DEBUG "%s: tx done %u\n", > dev->name, idx); > @@ -1836,16 +1845,12 @@ static void sky2_tx_complete(struct sky2 > dev->stats.tx_bytes += skb->len; > > dev_kfree_skb_any(skb); > - > - sky2->tx_next = RING_NEXT(idx, sky2->tx_ring_size); > } > } > > sky2->tx_cons = idx; > - smp_mb(); > > - /* Wake unless it's detached, and called e.g. from sky2_down() */ > - if (tx_avail(sky2) > MAX_SKB_TX_LE + 4 && netif_device_present(dev)) > + if (tx_avail(sky2) > MAX_SKB_TX_LE + 4) > netif_wake_queue(dev); > } > > @@ -1871,6 +1876,21 @@ static void sky2_tx_reset(struct sky2_hw > sky2_write8(hw, SK_REG(port, TX_GMF_CTRL_T), GMF_RST_SET); > } > > +static void sky2_tx_clean(struct sky2_port *sky2) > +{ > + u16 idx; > + > + for (idx = 0; idx < sky2->tx_ring_size; idx++) { > + struct tx_ring_info *re = sky2->tx_ring + idx; > + > + sky2_tx_unmap(sky2->hw->pdev, re); > + if (re->skb) { > + dev_kfree_skb_any(re->skb); > + re->skb = NULL; > + } > + } > +} > + > /* Network shutdown */ > static int sky2_down(struct net_device *dev) > { > @@ -1934,8 +1954,7 @@ static int sky2_down(struct net_device * > sky2_tx_reset(hw, port); > > /* Free any pending frames stuck in HW queue */ > - sky2_tx_complete(sky2, sky2->tx_prod); > - > + sky2_tx_clean(sky2); > sky2_rx_clean(sky2); > > sky2_free_buffers(sky2); > @@ -2412,15 +2431,6 @@ error: > goto resubmit; > } > > -/* Transmit complete */ > -static inline void sky2_tx_done(struct net_device *dev, u16 last) > -{ > - struct sky2_port *sky2 = netdev_priv(dev); > - > - if (netif_running(dev)) > - sky2_tx_complete(sky2, last); > -} > - > static inline void sky2_skb_rx(const struct sky2_port *sky2, > u32 status, struct sk_buff *skb) > { > @@ -3177,9 +3187,9 @@ static void sky2_reset(struct sky2_hw *h > static void sky2_detach(struct net_device *dev) > { > if (netif_running(dev)) { > - netif_tx_lock(dev); > + netif_tx_lock_bh(dev); > netif_device_detach(dev); /* stop txq */ > - netif_tx_unlock(dev); > + netif_tx_unlock_bh(dev); > sky2_down(dev); > } > } > @@ -4202,7 +4212,7 @@ static int sky2_debug_show(struct seq_fi > > /* Dump contents of tx ring */ > sop = 1; > - for (idx = sky2->tx_next; idx != sky2->tx_prod && idx < sky2->tx_ring_size; > + for (idx = sky2->tx_cons; idx != sky2->tx_prod && idx < sky2->tx_ring_size; > idx = RING_NEXT(idx, sky2->tx_ring_size)) { > const struct sky2_tx_le *le = sky2->tx_le + idx; > u32 a = le32_to_cpu(le->addr); > --- a/drivers/net/sky2.h 2010-01-13 08:32:27.919849429 -0800 > +++ b/drivers/net/sky2.h 2010-01-13 08:33:03.410162026 -0800 > @@ -2187,7 +2187,6 @@ struct sky2_port { > u16 tx_ring_size; > u16 tx_cons; /* next le to check */ > u16 tx_prod; /* next le to use */ > - u16 tx_next; /* debug only */ > > u16 tx_pending; > u16 tx_last_mss;