From: Michael Breuer <mbreuer@majjas•com>
To: Stephen Hemminger <shemminger@vyatta•com>
Cc: David Miller <davem@davemloft•net>,
jarkao2@gmail•com, mikem@ring3k•org, flyboy@gmail•com,
rjw@sisk•pl, netdev@vger•kernel.org
Subject: Re: [PATCH] sky2: safer transmit ring cleaning
Date: Tue, 12 Jan 2010 13:35:15 -0500 [thread overview]
Message-ID: <4B4CC0E3.5050106@majjas.com> (raw)
In-Reply-To: <20100112081513.0175d579@nehalam>
On 1/12/2010 11:15 AM, Stephen Hemminger wrote:
> 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
>
> Signed-off-by: Stephen Hemminger<shemminger@vyatta•com>
>
> ---
> Please apply this instead of the various bits and pieces flying
> around labeled as sky2 panic under load
>
>
> --- a/drivers/net/sky2.c 2010-01-11 10:49:50.907113126 -0800
> +++ b/drivers/net/sky2.c 2010-01-11 17:36:22.027429875 -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
> @@ -1813,9 +1817,9 @@ 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;
>
> BUG_ON(done>= sky2->tx_ring_size);
> @@ -1828,6 +1832,8 @@ 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);
> @@ -1836,13 +1842,10 @@ 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();
>
> if (tx_avail(sky2)> MAX_SKB_TX_LE + 4)
> netif_wake_queue(dev);
> @@ -1870,6 +1873,21 @@ 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)
> {
> @@ -1933,8 +1951,7 @@ 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);
> @@ -2411,15 +2428,6 @@ 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)
> {
> @@ -4201,7 +4209,7 @@ 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 2010-01-11 17:29:22.817088617 -0800
> +++ b/drivers/net/sky2.h 2010-01-11 17:29:28.197120484 -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;
>
Test observations:
1. DHCP request/response sequence having some issues... can't confirm
that it's a result of this patch, but I don't see this with the prior
patch. Prior to this patch, if I connect a new device (Blackberry in
this case) I see DHCPDISCOVER;DHCPOFFER;DHCPREQUEST;DHCPACK (just the
four messages). With this patch I'm seeing repeated attempts - i.e.,
DISCOVER/OFFER 6 times before the REQUEST/ACK. This is repeatable and
happening whether or not under load. As my original problem started with
DHCP packets, this seems interesting. I don't see any errors logged
(dmesg, messages, etc.).
2. Probably not related to this patch, but perhaps to the driver - I've
finally tracked the source of my dropped RX packets. It's happening when
a sending data to a CIFS client on a MacOS system. The RX drop rate
seems proportional to the TX rate for SMB to that client - at a tx rate
of about 200Kb/s I see about 20 dropped RX packets/sec - at 400 I see
about 40. I'm thinking therefore it's ACKs being dropped on RX. Why? no
idea (yet). Nothing reported by ethtool or netstat -s remotely
correlates to the number of dropped RX packets.
next prev parent reply other threads:[~2010-01-12 18:36 UTC|newest]
Thread overview: 59+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-01-10 22:27 2.6.33-rc3-git3: Reported regressions from 2.6.32 Rafael J. Wysocki
2010-01-10 22:32 ` [Bug #14925] sky2 panic under load Rafael J. Wysocki
2010-01-11 0:36 ` Berck E. Nash
2010-01-11 13:26 ` Jarek Poplawski
2010-01-11 19:32 ` Rafael J. Wysocki
2010-01-11 20:31 ` Jarek Poplawski
2010-01-11 20:50 ` Rafael J. Wysocki
2010-01-11 21:02 ` Berck E. Nash
2010-01-11 21:47 ` Jarek Poplawski
2010-01-11 14:03 ` Mike McCormack
2010-01-11 16:45 ` Stephen Hemminger
2010-01-11 22:07 ` Jarek Poplawski
2010-01-12 0:14 ` David Miller
2010-01-12 7:50 ` Jarek Poplawski
2010-01-12 8:08 ` David Miller
2010-01-12 8:56 ` Jarek Poplawski
2010-01-12 9:42 ` David Miller
2010-01-12 10:31 ` Jarek Poplawski
2010-01-12 10:56 ` David Miller
2010-01-12 11:04 ` Jarek Poplawski
2010-01-12 15:39 ` Stephen Hemminger
2010-01-12 16:15 ` [PATCH] sky2: safer transmit ring cleaning Stephen Hemminger
2010-01-12 16:32 ` Michael Breuer
2010-01-12 17:02 ` Stephen Hemminger
2010-01-12 18:04 ` Jarek Poplawski
2010-01-12 18:13 ` Stephen Hemminger
2010-01-12 18:24 ` Jarek Poplawski
2010-01-12 18:49 ` [PATCH] sky2: safer transmit ring cleaning (v2) Stephen Hemminger
2010-01-12 19:16 ` Jarek Poplawski
2010-01-12 19:23 ` Stephen Hemminger
2010-01-12 19:50 ` Jarek Poplawski
2010-01-13 1:23 ` Stephen Hemminger
2010-01-12 19:34 ` Michael Breuer
2010-01-12 18:35 ` Michael Breuer [this message]
2010-01-12 18:42 ` [PATCH] sky2: safer transmit ring cleaning Michael Breuer
2010-01-12 20:31 ` Michael Breuer
2010-01-13 4:10 ` [PATCH] sky2: safer transmit ring cleaning (v3) Stephen Hemminger
2010-01-13 4:31 ` Michael Breuer
2010-01-13 7:35 ` Jarek Poplawski
2010-01-13 16:04 ` Michael Breuer
2010-01-14 3:41 ` [PATCH] sky2: safer transmit ring cleaning (v4) Stephen Hemminger
2010-01-14 10:14 ` Jarek Poplawski
2010-01-14 11:16 ` Jarek Poplawski
2010-01-14 11:20 ` David Miller
2010-01-14 11:26 ` Jarek Poplawski
2010-01-14 13:19 ` Mike McCormack
2010-01-14 15:43 ` Michael Breuer
2010-01-14 16:46 ` Michael Breuer
2010-01-14 17:51 ` Stephen Hemminger
2010-01-14 17:52 ` Stephen Hemminger
2010-01-14 23:51 ` Michael Breuer
2010-01-16 18:35 ` sky2 DHCPOFFER packet loss under load (Was Re: [PATCH] sky2: safer transmit ring cleaning (v4)) Michael Breuer
2010-01-14 15:46 ` [PATCH] sky2: safer transmit ring cleaning (v4) Michael Breuer
2010-01-11 22:31 ` [Bug #14925] sky2 panic under load Jarek Poplawski
2010-01-11 16:00 ` 2.6.33-rc3-git3: Reported regressions from 2.6.32 Luis R. Rodriguez
2010-01-11 21:47 ` Nick Bowler
2010-01-11 22:10 ` Rafael J. Wysocki
[not found] ` <omZ8aBZReyD.A.rz.COlSLB@chimera>
2010-01-28 23:18 ` [PATCH net-2.6] cdc_ether: Partially revert "usbnet: Set link down initially ..." Ben Hutchings
2010-01-29 5:37 ` David Miller
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