Resubmit: [PATCH] natsemi: NAPI support

From: Mark Brown
Date: Wed Dec 21 2005 - 18:48:49 EST

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This patch against 2.6.14 converts the natsemi driver to use NAPI. It
was originally based on one written by Harald Welte, though it has since
been modified quite a bit, most extensively in order to remove the
ability to disable NAPI since none of the other drivers seem to provide
that functionality any more.

Signed-off-by: Mark Brown <broonie@xxxxxxxxxxxxx>

---

This revision of the patch:
- Doesn't sleep with the device spinlock held in suspend().
- Improves the synchronisation between poll() and the shutdown paths.

and should address all the issues people previously raised.

--- linux-2.6.14/drivers/net/natsemi.c.orig 2005-11-29 19:29:12.000000000 +0000
+++ linux/drivers/net/natsemi.c 2005-12-11 14:55:48.000000000 +0000
@@ -3,6 +3,7 @@
Written/copyright 1999-2001 by Donald Becker.
Portions copyright (c) 2001,2002 Sun Microsystems (thockin@xxxxxxx)
Portions copyright 2001,2002 Manfred Spraul (manfred@xxxxxxxxxxxxxxxx)
+ Portions copyright 2004 Harald Welte <laforge@xxxxxxxxxxxx>

This software may be used and distributed according to the terms of
the GNU General Public License (GPL), incorporated herein by reference.
@@ -135,8 +136,6 @@

TODO:
* big endian support with CFG:BEM instead of cpu_to_le32
- * support for an external PHY
- * NAPI
*/

#include <linux/config.h>
@@ -160,6 +159,7 @@
#include <linux/mii.h>
#include <linux/crc32.h>
#include <linux/bitops.h>
+#include <linux/prefetch.h>
#include <asm/processor.h> /* Processor type for cache alignment. */
#include <asm/io.h>
#include <asm/irq.h>
@@ -183,8 +183,6 @@
NETIF_MSG_TX_ERR)
static int debug = -1;

-/* Maximum events (Rx packets, etc.) to handle at each interrupt. */
-static int max_interrupt_work = 20;
static int mtu;

/* Maximum number of multicast addresses to filter (vs. rx-all-multicast).
@@ -251,14 +249,11 @@ MODULE_AUTHOR("Donald Becker <becker@scy
MODULE_DESCRIPTION("National Semiconductor DP8381x series PCI Ethernet driver");
MODULE_LICENSE("GPL");

-module_param(max_interrupt_work, int, 0);
module_param(mtu, int, 0);
module_param(debug, int, 0);
module_param(rx_copybreak, int, 0);
module_param_array(options, int, NULL, 0);
module_param_array(full_duplex, int, NULL, 0);
-MODULE_PARM_DESC(max_interrupt_work,
- "DP8381x maximum events handled per interrupt");
MODULE_PARM_DESC(mtu, "DP8381x MTU (all boards)");
MODULE_PARM_DESC(debug, "DP8381x default debug level");
MODULE_PARM_DESC(rx_copybreak,
@@ -691,6 +686,8 @@ struct netdev_private {
/* Based on MTU+slack. */
unsigned int rx_buf_sz;
int oom;
+ /* Interrupt status */
+ u32 intr_status;
/* Do not touch the nic registers */
int hands_off;
/* external phy that is used: only valid if dev->if_port != PORT_TP */
@@ -748,7 +745,8 @@ static void init_registers(struct net_de
static int start_tx(struct sk_buff *skb, struct net_device *dev);
static irqreturn_t intr_handler(int irq, void *dev_instance, struct pt_regs *regs);
static void netdev_error(struct net_device *dev, int intr_status);
-static void netdev_rx(struct net_device *dev);
+static int natsemi_poll(struct net_device *dev, int *budget);
+static void netdev_rx(struct net_device *dev, int *work_done, int work_to_do);
static void netdev_tx_done(struct net_device *dev);
static int natsemi_change_mtu(struct net_device *dev, int new_mtu);
#ifdef CONFIG_NET_POLL_CONTROLLER
@@ -776,6 +774,18 @@ static inline void __iomem *ns_ioaddr(st
return (void __iomem *) dev->base_addr;
}

+static inline void natsemi_irq_enable(struct net_device *dev)
+{
+ writel(1, ns_ioaddr(dev) + IntrEnable);
+ readl(ns_ioaddr(dev) + IntrEnable);
+}
+
+static inline void natsemi_irq_disable(struct net_device *dev)
+{
+ writel(0, ns_ioaddr(dev) + IntrEnable);
+ readl(ns_ioaddr(dev) + IntrEnable);
+}
+
static void move_int_phy(struct net_device *dev, int addr)
{
struct netdev_private *np = netdev_priv(dev);
@@ -879,6 +889,7 @@ static int __devinit natsemi_probe1 (str
spin_lock_init(&np->lock);
np->msg_enable = (debug >= 0) ? (1<<debug)-1 : NATSEMI_DEF_MSG;
np->hands_off = 0;
+ np->intr_status = 0;

/* Initial port:
* - If the nic was configured to use an external phy and if find_mii
@@ -932,6 +943,9 @@ static int __devinit natsemi_probe1 (str
dev->do_ioctl = &netdev_ioctl;
dev->tx_timeout = &tx_timeout;
dev->watchdog_timeo = TX_TIMEOUT;
+ dev->poll = natsemi_poll;
+ dev->weight = 64;
+
#ifdef CONFIG_NET_POLL_CONTROLLER
dev->poll_controller = &natsemi_poll_controller;
#endif
@@ -2158,68 +2172,92 @@ static void netdev_tx_done(struct net_de
}
}

-/* The interrupt handler does all of the Rx thread work and cleans up
- after the Tx thread. */
+/* The interrupt handler doesn't actually handle interrupts itself, it
+ * schedules a NAPI poll if there is anything to do. */
static irqreturn_t intr_handler(int irq, void *dev_instance, struct pt_regs *rgs)
{
struct net_device *dev = dev_instance;
struct netdev_private *np = netdev_priv(dev);
void __iomem * ioaddr = ns_ioaddr(dev);
- int boguscnt = max_interrupt_work;
- unsigned int handled = 0;

if (np->hands_off)
return IRQ_NONE;
- do {
- /* Reading automatically acknowledges all int sources. */
- u32 intr_status = readl(ioaddr + IntrStatus);
+
+ /* Reading automatically acknowledges. */
+ np->intr_status = readl(ioaddr + IntrStatus);

- if (netif_msg_intr(np))
- printk(KERN_DEBUG
- "%s: Interrupt, status %#08x, mask %#08x.\n",
- dev->name, intr_status,
- readl(ioaddr + IntrMask));
+ if (netif_msg_intr(np))
+ printk(KERN_DEBUG
+ "%s: Interrupt, status %#08x, mask %#08x.\n",
+ dev->name, np->intr_status,
+ readl(ioaddr + IntrMask));

- if (intr_status == 0)
- break;
- handled = 1;
+ if (!np->intr_status)
+ return IRQ_NONE;

- if (intr_status &
- (IntrRxDone | IntrRxIntr | RxStatusFIFOOver |
- IntrRxErr | IntrRxOverrun)) {
- netdev_rx(dev);
- }
+ prefetch(&np->rx_skbuff[np->cur_rx % RX_RING_SIZE]);
+
+ if (netif_rx_schedule_prep(dev)) {
+ /* Disable interrupts and register for poll */
+ natsemi_irq_disable(dev);
+ __netif_rx_schedule(dev);
+ }
+ return IRQ_HANDLED;
+}

- if (intr_status &
- (IntrTxDone | IntrTxIntr | IntrTxIdle | IntrTxErr)) {
+/* This is the NAPI poll routine. As well as the standard RX handling
+ * it also handles all other interrupts that the chip might raise.
+ */
+static int natsemi_poll(struct net_device *dev, int *budget)
+{
+ struct netdev_private *np = netdev_priv(dev);
+ void __iomem * ioaddr = ns_ioaddr(dev);
+
+ int work_to_do = min(*budget, dev->quota);
+ int work_done = 0;
+
+ do {
+ if (np->intr_status &
+ (IntrTxDone | IntrTxIntr | IntrTxIdle | IntrTxErr)) {
spin_lock(&np->lock);
netdev_tx_done(dev);
spin_unlock(&np->lock);
}

/* Abnormal error summary/uncommon events handlers. */
- if (intr_status & IntrAbnormalSummary)
- netdev_error(dev, intr_status);
-
- if (--boguscnt < 0) {
- if (netif_msg_intr(np))
- printk(KERN_WARNING
- "%s: Too much work at interrupt, "
- "status=%#08x.\n",
- dev->name, intr_status);
- break;
+ if (np->intr_status & IntrAbnormalSummary)
+ netdev_error(dev, np->intr_status);
+
+ if (np->intr_status &
+ (IntrRxDone | IntrRxIntr | RxStatusFIFOOver |
+ IntrRxErr | IntrRxOverrun)) {
+ netdev_rx(dev, &work_done, work_to_do);
}
- } while (1);
+
+ *budget -= work_done;
+ dev->quota -= work_done;

- if (netif_msg_intr(np))
- printk(KERN_DEBUG "%s: exiting interrupt.\n", dev->name);
+ if (work_done >= work_to_do)
+ return 1;
+
+ np->intr_status = readl(ioaddr + IntrStatus);
+ } while (np->intr_status);

- return IRQ_RETVAL(handled);
+ netif_rx_complete(dev);
+
+ /* Reenable interrupts providing nothing is trying to shut
+ * the chip down. */
+ spin_lock(&np->lock);
+ if (!np->hands_off && netif_running(dev))
+ natsemi_irq_enable(dev);
+ spin_unlock(&np->lock);
+
+ return 0;
}

/* This routine is logically part of the interrupt handler, but separated
for clarity and better register allocation. */
-static void netdev_rx(struct net_device *dev)
+static void netdev_rx(struct net_device *dev, int *work_done, int work_to_do)
{
struct netdev_private *np = netdev_priv(dev);
int entry = np->cur_rx % RX_RING_SIZE;
@@ -2237,6 +2275,12 @@ static void netdev_rx(struct net_device
entry, desc_status);
if (--boguscnt < 0)
break;
+
+ if (*work_done >= work_to_do)
+ break;
+
+ (*work_done)++;
+
pkt_len = (desc_status & DescSizeMask) - 4;
if ((desc_status&(DescMore|DescPktOK|DescRxLong)) != DescPktOK){
if (desc_status & DescMore) {
@@ -2293,7 +2337,7 @@ static void netdev_rx(struct net_device
np->rx_skbuff[entry] = NULL;
}
skb->protocol = eth_type_trans(skb, dev);
- netif_rx(skb);
+ netif_receive_skb(skb);
dev->last_rx = jiffies;
np->stats.rx_packets++;
np->stats.rx_bytes += pkt_len;
@@ -3074,9 +3118,7 @@ static int netdev_close(struct net_devic
del_timer_sync(&np->timer);
disable_irq(dev->irq);
spin_lock_irq(&np->lock);
- /* Disable interrupts, and flush posted writes */
- writel(0, ioaddr + IntrEnable);
- readl(ioaddr + IntrEnable);
+ natsemi_irq_disable(dev);
np->hands_off = 1;
spin_unlock_irq(&np->lock);
enable_irq(dev->irq);
@@ -3158,6 +3200,9 @@ static void __devexit natsemi_remove1 (s
* * netdev_timer: timer stopped by natsemi_suspend.
* * intr_handler: doesn't acquire the spinlock. suspend calls
* disable_irq() to enforce synchronization.
+ * * natsemi_poll: checks before reenabling interrupts. suspend
+ * sets hands_off, disables interrupts and then waits with
+ * netif_poll_disable().
*
* Interrupts must be disabled, otherwise hands_off can cause irq storms.
*/
@@ -3183,6 +3228,8 @@ static int natsemi_suspend (struct pci_d
spin_unlock_irq(&np->lock);
enable_irq(dev->irq);

+ netif_poll_disable(dev);
+
/* Update the error counts. */
__get_stats(dev);

@@ -3235,6 +3282,7 @@ static int natsemi_resume (struct pci_de
mod_timer(&np->timer, jiffies + 1*HZ);
}
netif_device_attach(dev);
+ netif_poll_enable(dev);
out:
rtnl_unlock();
return 0;

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Next message: Lee Revell: "[PATCH] Un-deprecate inter_module_*"
Previous message: Gene Heskett: "Re: Sensors errors with 15-rc6, 15-rc5 was normal"
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