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lguest: fix comment style

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I don't really notice it (except to begrudge the extra vertical
space), but Ingo does.  And he pointed out that one excuse of lguest
is as a teaching tool, it should set a good example.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Ingo Molnar <mingo@redhat.com>
This commit is contained in:
Rusty Russell
2009-07-30 16:03:45 -06:00
parent e969fed542
commit 2e04ef7691
17 changed files with 1906 additions and 1015 deletions
Download Patch File Download Diff File Expand all files Collapse all files

150
drivers/lguest/lguest_device.c
View File

@@ -1,10 +1,12 @@
/*P:050 Lguest guests use a very simple method to describe devices. It's a
/*P:050
* Lguest guests use a very simple method to describe devices. It's a
* series of device descriptors contained just above the top of normal Guest
* memory.
*
* We use the standard "virtio" device infrastructure, which provides us with a
* console, a network and a block driver. Each one expects some configuration
* information and a "virtqueue" or two to send and receive data. :*/
* information and a "virtqueue" or two to send and receive data.
:*/
#include <linux/init.h>
#include <linux/bootmem.h>
#include <linux/lguest_launcher.h>
@@ -20,8 +22,10 @@
/* The pointer to our (page) of device descriptions. */
static void *lguest_devices;
/* For Guests, device memory can be used as normal memory, so we cast away the
* __iomem to quieten sparse. */
/*
* For Guests, device memory can be used as normal memory, so we cast away the
* __iomem to quieten sparse.
*/
static inline void *lguest_map(unsigned long phys_addr, unsigned long pages)
{
return (__force void *)ioremap_cache(phys_addr, PAGE_SIZE*pages);
@@ -32,8 +36,10 @@ static inline void lguest_unmap(void *addr)
iounmap((__force void __iomem *)addr);
}
/*D:100 Each lguest device is just a virtio device plus a pointer to its entry
* in the lguest_devices page. */
/*D:100
* Each lguest device is just a virtio device plus a pointer to its entry
* in the lguest_devices page.
*/
struct lguest_device {
struct virtio_device vdev;
@@ -41,9 +47,11 @@ struct lguest_device {
struct lguest_device_desc *desc;
};
/* Since the virtio infrastructure hands us a pointer to the virtio_device all
/*
* Since the virtio infrastructure hands us a pointer to the virtio_device all
* the time, it helps to have a curt macro to get a pointer to the struct
* lguest_device it's enclosed in. */
* lguest_device it's enclosed in.
*/
#define to_lgdev(vd) container_of(vd, struct lguest_device, vdev)
/*D:130
@@ -55,7 +63,8 @@ struct lguest_device {
* the driver will look at them during setup.
*
* A convenient routine to return the device's virtqueue config array:
* immediately after the descriptor. */
* immediately after the descriptor.
*/
static struct lguest_vqconfig *lg_vq(const struct lguest_device_desc *desc)
{
return (void *)(desc + 1);
@@ -98,10 +107,12 @@ static u32 lg_get_features(struct virtio_device *vdev)
return features;
}
/* The virtio core takes the features the Host offers, and copies the
* ones supported by the driver into the vdev->features array. Once
* that's all sorted out, this routine is called so we can tell the
* Host which features we understand and accept. */
/*
* The virtio core takes the features the Host offers, and copies the ones
* supported by the driver into the vdev->features array. Once that's all
* sorted out, this routine is called so we can tell the Host which features we
* understand and accept.
*/
static void lg_finalize_features(struct virtio_device *vdev)
{
unsigned int i, bits;
@@ -112,10 +123,11 @@ static void lg_finalize_features(struct virtio_device *vdev)
/* Give virtio_ring a chance to accept features. */
vring_transport_features(vdev);
/* The vdev->feature array is a Linux bitmask: this isn't the
* same as a the simple array of bits used by lguest devices
* for features. So we do this slow, manual conversion which is
* completely general. */
/*
* The vdev->feature array is a Linux bitmask: this isn't the same as a
* the simple array of bits used by lguest devices for features. So we
* do this slow, manual conversion which is completely general.
*/
memset(out_features, 0, desc->feature_len);
bits = min_t(unsigned, desc->feature_len, sizeof(vdev->features)) * 8;
for (i = 0; i < bits; i++) {
@@ -146,15 +158,19 @@ static void lg_set(struct virtio_device *vdev, unsigned int offset,
memcpy(lg_config(desc) + offset, buf, len);
}
/* The operations to get and set the status word just access the status field
* of the device descriptor. */
/*
* The operations to get and set the status word just access the status field
* of the device descriptor.
*/
static u8 lg_get_status(struct virtio_device *vdev)
{
return to_lgdev(vdev)->desc->status;
}
/* To notify on status updates, we (ab)use the NOTIFY hypercall, with the
* descriptor address of the device. A zero status means "reset". */
/*
* To notify on status updates, we (ab)use the NOTIFY hypercall, with the
* descriptor address of the device. A zero status means "reset".
*/
static void set_status(struct virtio_device *vdev, u8 status)
{
unsigned long offset = (void *)to_lgdev(vdev)->desc - lguest_devices;
@@ -200,13 +216,17 @@ struct lguest_vq_info
void *pages;
};
/* When the virtio_ring code wants to prod the Host, it calls us here and we
/*
* When the virtio_ring code wants to prod the Host, it calls us here and we
* make a hypercall. We hand the physical address of the virtqueue so the Host
* knows which virtqueue we're talking about. */
* knows which virtqueue we're talking about.
*/
static void lg_notify(struct virtqueue *vq)
{
/* We store our virtqueue information in the "priv" pointer of the
* virtqueue structure. */
/*
* We store our virtqueue information in the "priv" pointer of the
* virtqueue structure.
*/
struct lguest_vq_info *lvq = vq->priv;
kvm_hypercall1(LHCALL_NOTIFY, lvq->config.pfn << PAGE_SHIFT);
@@ -215,7 +235,8 @@ static void lg_notify(struct virtqueue *vq)
/* An extern declaration inside a C file is bad form. Don't do it. */
extern void lguest_setup_irq(unsigned int irq);
/* This routine finds the first virtqueue described in the configuration of
/*
* This routine finds the first virtqueue described in the configuration of
* this device and sets it up.
*
* This is kind of an ugly duckling. It'd be nicer to have a standard
@@ -225,7 +246,8 @@ extern void lguest_setup_irq(unsigned int irq);
* simpler for the Host to simply tell us where the pages are.
*
* So we provide drivers with a "find the Nth virtqueue and set it up"
* function. */
* function.
*/
static struct virtqueue *lg_find_vq(struct virtio_device *vdev,
unsigned index,
void (*callback)(struct virtqueue *vq),
@@ -244,9 +266,11 @@ static struct virtqueue *lg_find_vq(struct virtio_device *vdev,
if (!lvq)
return ERR_PTR(-ENOMEM);
/* Make a copy of the "struct lguest_vqconfig" entry, which sits after
/*
* Make a copy of the "struct lguest_vqconfig" entry, which sits after
* the descriptor. We need a copy because the config space might not
* be aligned correctly. */
* be aligned correctly.
*/
memcpy(&lvq->config, lg_vq(ldev->desc)+index, sizeof(lvq->config));
printk("Mapping virtqueue %i addr %lx\n", index,
@@ -261,8 +285,10 @@ static struct virtqueue *lg_find_vq(struct virtio_device *vdev,
goto free_lvq;
}
/* OK, tell virtio_ring.c to set up a virtqueue now we know its size
* and we've got a pointer to its pages. */
/*
* OK, tell virtio_ring.c to set up a virtqueue now we know its size
* and we've got a pointer to its pages.
*/
vq = vring_new_virtqueue(lvq->config.num, LGUEST_VRING_ALIGN,
vdev, lvq->pages, lg_notify, callback, name);
if (!vq) {
@@ -273,18 +299,23 @@ static struct virtqueue *lg_find_vq(struct virtio_device *vdev,
/* Make sure the interrupt is allocated. */
lguest_setup_irq(lvq->config.irq);
/* Tell the interrupt for this virtqueue to go to the virtio_ring
* interrupt handler. */
/* FIXME: We used to have a flag for the Host to tell us we could use
/*
* Tell the interrupt for this virtqueue to go to the virtio_ring
* interrupt handler.
*
* FIXME: We used to have a flag for the Host to tell us we could use
* the interrupt as a source of randomness: it'd be nice to have that
* back.. */
* back.
*/
err = request_irq(lvq->config.irq, vring_interrupt, IRQF_SHARED,
dev_name(&vdev->dev), vq);
if (err)
goto destroy_vring;
/* Last of all we hook up our 'struct lguest_vq_info" to the
* virtqueue's priv pointer. */
/*
* Last of all we hook up our 'struct lguest_vq_info" to the
* virtqueue's priv pointer.
*/
vq->priv = lvq;
return vq;
@@ -358,11 +389,14 @@ static struct virtio_config_ops lguest_config_ops = {
.del_vqs = lg_del_vqs,
};
/* The root device for the lguest virtio devices. This makes them appear as
* /sys/devices/lguest/0,1,2 not /sys/devices/0,1,2. */
/*
* The root device for the lguest virtio devices. This makes them appear as
* /sys/devices/lguest/0,1,2 not /sys/devices/0,1,2.
*/
static struct device *lguest_root;
/*D:120 This is the core of the lguest bus: actually adding a new device.
/*D:120
* This is the core of the lguest bus: actually adding a new device.
* It's a separate function because it's neater that way, and because an
* earlier version of the code supported hotplug and unplug. They were removed
* early on because they were never used.
@@ -371,14 +405,14 @@ static struct device *lguest_root;
*
* It's worth reading this carefully: we start with a pointer to the new device
* descriptor in the "lguest_devices" page, and the offset into the device
* descriptor page so we can uniquely identify it if things go badly wrong. */
* descriptor page so we can uniquely identify it if things go badly wrong.
*/
static void add_lguest_device(struct lguest_device_desc *d,
unsigned int offset)
{
struct lguest_device *ldev;
/* Start with zeroed memory; Linux's device layer seems to count on
* it. */
/* Start with zeroed memory; Linux's device layer counts on it. */
ldev = kzalloc(sizeof(*ldev), GFP_KERNEL);
if (!ldev) {
printk(KERN_EMERG "Cannot allocate lguest dev %u type %u\n",
@@ -390,15 +424,19 @@ static void add_lguest_device(struct lguest_device_desc *d,
ldev->vdev.dev.parent = lguest_root;
/* We have a unique device index thanks to the dev_index counter. */
ldev->vdev.id.device = d->type;
/* We have a simple set of routines for querying the device's
* configuration information and setting its status. */
/*
* We have a simple set of routines for querying the device's
* configuration information and setting its status.
*/
ldev->vdev.config = &lguest_config_ops;
/* And we remember the device's descriptor for lguest_config_ops. */
ldev->desc = d;
/* register_virtio_device() sets up the generic fields for the struct
/*
* register_virtio_device() sets up the generic fields for the struct
* virtio_device and calls device_register(). This makes the bus
* infrastructure look for a matching driver. */
* infrastructure look for a matching driver.
*/
if (register_virtio_device(&ldev->vdev) != 0) {
printk(KERN_ERR "Failed to register lguest dev %u type %u\n",
offset, d->type);
@@ -406,8 +444,10 @@ static void add_lguest_device(struct lguest_device_desc *d,
}
}
/*D:110 scan_devices() simply iterates through the device page. The type 0 is
* reserved to mean "end of devices". */
/*D:110
* scan_devices() simply iterates through the device page. The type 0 is
* reserved to mean "end of devices".
*/
static void scan_devices(void)
{
unsigned int i;
@@ -426,7 +466,8 @@ static void scan_devices(void)
}
}
/*D:105 Fairly early in boot, lguest_devices_init() is called to set up the
/*D:105
* Fairly early in boot, lguest_devices_init() is called to set up the
* lguest device infrastructure. We check that we are a Guest by checking
* pv_info.name: there are other ways of checking, but this seems most
* obvious to me.
@@ -437,7 +478,8 @@ static void scan_devices(void)
* correct sysfs incantation).
*
* Finally we call scan_devices() which adds all the devices found in the
* lguest_devices page. */
* lguest_devices page.
*/
static int __init lguest_devices_init(void)
{
if (strcmp(pv_info.name, "lguest") != 0)
@@ -456,11 +498,13 @@ static int __init lguest_devices_init(void)
/* We do this after core stuff, but before the drivers. */
postcore_initcall(lguest_devices_init);
/*D:150 At this point in the journey we used to now wade through the lguest
/*D:150
* At this point in the journey we used to now wade through the lguest
* devices themselves: net, block and console. Since they're all now virtio
* devices rather than lguest-specific, I've decided to ignore them. Mostly,
* they're kind of boring. But this does mean you'll never experience the
* thrill of reading the forbidden love scene buried deep in the block driver.
*
* "make Launcher" beckons, where we answer questions like "Where do Guests
* come from?", and "What do you do when someone asks for optimization?". */
* come from?", and "What do you do when someone asks for optimization?".
*/