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Date: Wed, 13 Jan 2010 19:41:48 -0800
From: Stephen Hemminger <shemminger@...tta.com>
To: Michael Breuer <mbreuer@...jas.com>,
David Miller <davem@...emloft.net>
Cc: jarkao2@...il.com, mikem@...g3k.org, flyboy@...il.com, rjw@...k.pl,
netdev@...r.kernel.org
Subject: Re: [PATCH] sky2: safer transmit ring cleaning (v4)
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 <shemminger@...tta.com>
---
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)))
+ 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;
--
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