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Message-Id: <1178791976.7286.221.camel@localhost.localdomain>
Date: Thu, 10 May 2007 20:12:56 +1000
From: Rusty Russell <rusty@...tcorp.com.au>
To: Jeff Garzik <jeff@...zik.org>
Cc: akpm@...ux-foundation.org, linux-kernel@...r.kernel.org,
virtualization@...ts.osdl.org, ak@...e.de, jmorris@...ei.org
Subject: Re: [patch 7/9] lguest: the net driver
On Thu, 2007-05-10 at 01:33 -0400, Jeff Garzik wrote:
> Rusty Russell wrote:
> > I realize your continual battle with this, but adding a layer of
> > indirection doesn't seem like it will add clarity. The issues with
> > __pa() are reasonably known (don't hand it a vmalloc address, for
> > example). Any wrapper I create would be another hurdle to jump 8(
>
> You don't want this low level stuff in drivers.
[snip answers]
Hi Jeff,
This email was illuminating, thanks. I've put NAPI, set_mac_address
and module unload in the documentation patch for future enthusiasts.
The rest is implemented here.
Here's the extract from my current "feedback" patch:
...
2) Jeff Garzik
- Use netdev_priv instead of dev->priv.
- Check for ioremap failure
- iounmap on failure.
- Wrap SEND_DMA and BIND_DMA calls
- Don't set NETIF_F_SG unless we set NETIF_F_NO_CSUM
- Use SET_NETDEV_DEV()
- Don't set dev->irq, mem_start & mem_end (deprecated)
diff -r 35c8b37f8d3c drivers/lguest/lguest.c
--- a/drivers/lguest/lguest.c Wed May 09 23:23:56 2007 +1000
+++ b/drivers/lguest/lguest.c Thu May 10 20:06:25 2007 +1000
@@ -27,6 +27,7 @@
#include <linux/interrupt.h>
#include <linux/lguest.h>
#include <linux/lguest_launcher.h>
+#include <linux/lguest_bus.h>
#include <asm/paravirt.h>
#include <asm/param.h>
#include <asm/page.h>
@@ -99,6 +100,25 @@ void async_hcall(unsigned long call,
next_call = 0;
}
local_irq_restore(flags);
+}
+
+void lguest_send_dma(unsigned long key, struct lguest_dma *dma)
+{
+ dma->used_len = 0;
+ hcall(LHCALL_SEND_DMA, key, __pa(dma), 0);
+}
+
+int lguest_bind_dma(unsigned long key, struct lguest_dma *dmas,
+ unsigned int num, u8 irq)
+{
+ if (!hcall(LHCALL_BIND_DMA, key, __pa(dmas), (num << 8) | irq))
+ return -ENOMEM;
+ return 0;
+}
+
+void lguest_unbind_dma(unsigned long key, struct lguest_dma *dmas)
+{
+ hcall(LHCALL_BIND_DMA, key, __pa(dmas), 0);
}
static unsigned long save_fl(void)
diff -r 35c8b37f8d3c drivers/net/lguest_net.c
--- a/drivers/net/lguest_net.c Wed May 09 23:23:56 2007 +1000
+++ b/drivers/net/lguest_net.c Thu May 10 19:30:21 2007 +1000
@@ -35,6 +35,9 @@ struct lguestnet_info
unsigned long peer_phys;
unsigned long mapsize;
+ /* The lguest_device I come from */
+ struct lguest_device *lgdev;
+
/* My peerid. */
unsigned int me;
@@ -84,7 +87,7 @@ static void skb_to_dma(const struct sk_b
static void lguestnet_set_multicast(struct net_device *dev)
{
- struct lguestnet_info *info = dev->priv;
+ struct lguestnet_info *info = netdev_priv(dev);
if ((dev->flags & (IFF_PROMISC|IFF_ALLMULTI)) || dev->mc_count)
info->peer[info->me].mac[0] |= PROMISC_BIT;
@@ -110,13 +113,13 @@ static void transfer_packet(struct net_d
struct sk_buff *skb,
unsigned int peernum)
{
- struct lguestnet_info *info = dev->priv;
+ struct lguestnet_info *info = netdev_priv(dev);
struct lguest_dma dma;
skb_to_dma(skb, skb_headlen(skb), &dma);
pr_debug("xfer length %04x (%u)\n", htons(skb->len), skb->len);
- hcall(LHCALL_SEND_DMA, peer_key(info,peernum), __pa(&dma), 0);
+ lguest_send_dma(peer_key(info, peernum), &dma);
if (dma.used_len != skb->len) {
dev->stats.tx_carrier_errors++;
pr_debug("Bad xfer to peer %i: %i of %i (dma %p/%i)\n",
@@ -137,7 +140,7 @@ static int lguestnet_start_xmit(struct s
{
unsigned int i;
int broadcast;
- struct lguestnet_info *info = dev->priv;
+ struct lguestnet_info *info = netdev_priv(dev);
const unsigned char *dest = ((struct ethhdr *)skb->data)->h_dest;
pr_debug("%s: xmit %02x:%02x:%02x:%02x:%02x:%02x\n",
@@ -162,7 +165,7 @@ static int lguestnet_start_xmit(struct s
/* Find a new skb to put in this slot in shared mem. */
static int fill_slot(struct net_device *dev, unsigned int slot)
{
- struct lguestnet_info *info = dev->priv;
+ struct lguestnet_info *info = netdev_priv(dev);
/* Try to create and register a new one. */
info->skb[slot] = netdev_alloc_skb(dev, ETH_HLEN + ETH_DATA_LEN);
if (!info->skb[slot]) {
@@ -180,7 +183,7 @@ static irqreturn_t lguestnet_rcv(int irq
static irqreturn_t lguestnet_rcv(int irq, void *dev_id)
{
struct net_device *dev = dev_id;
- struct lguestnet_info *info = dev->priv;
+ struct lguestnet_info *info = netdev_priv(dev);
unsigned int i, done = 0;
for (i = 0; i < ARRAY_SIZE(info->dma); i++) {
@@ -220,7 +223,7 @@ static int lguestnet_open(struct net_dev
static int lguestnet_open(struct net_device *dev)
{
int i;
- struct lguestnet_info *info = dev->priv;
+ struct lguestnet_info *info = netdev_priv(dev);
/* Set up our MAC address */
memcpy(info->peer[info->me].mac, dev->dev_addr, ETH_ALEN);
@@ -232,8 +235,8 @@ static int lguestnet_open(struct net_dev
if (fill_slot(dev, i) != 0)
goto cleanup;
}
- if (!hcall(LHCALL_BIND_DMA, peer_key(info, info->me), __pa(info->dma),
- (NUM_SKBS << 8) | dev->irq))
+ if (lguest_bind_dma(peer_key(info,info->me), info->dma,
+ NUM_SKBS, lgdev_irq(info->lgdev)) != 0)
goto cleanup;
return 0;
@@ -246,13 +249,13 @@ static int lguestnet_close(struct net_de
static int lguestnet_close(struct net_device *dev)
{
unsigned int i;
- struct lguestnet_info *info = dev->priv;
+ struct lguestnet_info *info = netdev_priv(dev);
/* Clear all trace: others might deliver packets, we'll ignore it. */
memset(&info->peer[info->me], 0, sizeof(info->peer[info->me]));
/* Deregister sg lists. */
- hcall(LHCALL_BIND_DMA, peer_key(info, info->me), __pa(info->dma), 0);
+ lguest_unbind_dma(peer_key(info, info->me), info->dma);
for (i = 0; i < ARRAY_SIZE(info->dma); i++)
dev_kfree_skb(info->skb[i]);
return 0;
@@ -290,30 +293,34 @@ static int lguestnet_probe(struct lguest
/* Turning on/off promisc will call dev->set_multicast_list.
* We don't actually support multicast yet */
dev->set_multicast_list = lguestnet_set_multicast;
- dev->mem_start = ((unsigned long)desc->pfn << PAGE_SHIFT);
- dev->mem_end = dev->mem_start + PAGE_SIZE * desc->num_pages;
- dev->irq = lgdev->index+1;
- dev->features = NETIF_F_SG;
+ SET_NETDEV_DEV(dev, &lgdev->dev);
if (desc->features & LGUEST_NET_F_NOCSUM)
- dev->features |= NETIF_F_NO_CSUM;
-
- info = dev->priv;
+ dev->features = NETIF_F_SG|NETIF_F_NO_CSUM;
+
+ info = netdev_priv(dev);
info->mapsize = PAGE_SIZE * desc->num_pages;
info->peer_phys = ((unsigned long)desc->pfn << PAGE_SHIFT);
- info->peer = (void *)ioremap(info->peer_phys, info->mapsize);
+ info->lgdev = lgdev;
+ info->peer = (__force void *)ioremap(info->peer_phys, info->mapsize);
+ if (!info->peer) {
+ err = -ENOMEM;
+ goto free;
+ }
+
/* This stores our peerid (upper bits reserved for future). */
info->me = (desc->features & (info->mapsize-1));
err = register_netdev(dev);
if (err) {
pr_debug("lguestnet: registering device failed\n");
- goto free;
+ goto unmap;
}
if (lguest_devices[lgdev->index].features & LGUEST_DEVICE_F_RANDOMNESS)
irqf |= IRQF_SAMPLE_RANDOM;
- if (request_irq(dev->irq, lguestnet_rcv, irqf, "lguestnet", dev) != 0) {
- pr_debug("lguestnet: could not get net irq %i\n", dev->irq);
+ if (request_irq(lgdev_irq(lgdev), lguestnet_rcv, irqf, "lguestnet",
+ dev) != 0) {
+ pr_debug("lguestnet: cannot get irq %i\n", lgdev_irq(lgdev));
goto unregister;
}
@@ -323,6 +330,8 @@ static int lguestnet_probe(struct lguest
unregister:
unregister_netdev(dev);
+unmap:
+ iounmap((__force void __iomem *)info->peer);
free:
free_netdev(dev);
return err;
diff -r 35c8b37f8d3c include/linux/lguest_bus.h
--- a/include/linux/lguest_bus.h Wed May 09 23:23:56 2007 +1000
+++ b/include/linux/lguest_bus.h Thu May 10 19:29:14 2007 +1000
@@ -7,7 +7,6 @@
struct lguest_device {
/* Unique busid, and index into lguest_page->devices[] */
- /* By convention, each device can use irq index+1 if it wants to. */
unsigned int index;
struct device dev;
@@ -15,6 +14,18 @@ struct lguest_device {
/* Driver can hang data off here. */
void *private;
};
+
+/* By convention, each device can use irq index+1 if it wants to. */
+static inline int lgdev_irq(const struct lguest_device *dev)
+{
+ return dev->index + 1;
+}
+
+/* dma args must not be vmalloced! */
+void lguest_send_dma(unsigned long key, struct lguest_dma *dma);
+int lguest_bind_dma(unsigned long key, struct lguest_dma *dmas,
+ unsigned int num, u8 irq);
+void lguest_unbind_dma(unsigned long key, struct lguest_dma *dmas);
struct lguest_driver {
const char *name;
-
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