linux/drivers/usb/misc/usblcd.c
Arnd Bergmann 6038f373a3 llseek: automatically add .llseek fop
All file_operations should get a .llseek operation so we can make
nonseekable_open the default for future file operations without a
.llseek pointer.

The three cases that we can automatically detect are no_llseek, seq_lseek
and default_llseek. For cases where we can we can automatically prove that
the file offset is always ignored, we use noop_llseek, which maintains
the current behavior of not returning an error from a seek.

New drivers should normally not use noop_llseek but instead use no_llseek
and call nonseekable_open at open time.  Existing drivers can be converted
to do the same when the maintainer knows for certain that no user code
relies on calling seek on the device file.

The generated code is often incorrectly indented and right now contains
comments that clarify for each added line why a specific variant was
chosen. In the version that gets submitted upstream, the comments will
be gone and I will manually fix the indentation, because there does not
seem to be a way to do that using coccinelle.

Some amount of new code is currently sitting in linux-next that should get
the same modifications, which I will do at the end of the merge window.

Many thanks to Julia Lawall for helping me learn to write a semantic
patch that does all this.

===== begin semantic patch =====
// This adds an llseek= method to all file operations,
// as a preparation for making no_llseek the default.
//
// The rules are
// - use no_llseek explicitly if we do nonseekable_open
// - use seq_lseek for sequential files
// - use default_llseek if we know we access f_pos
// - use noop_llseek if we know we don't access f_pos,
//   but we still want to allow users to call lseek
//
@ open1 exists @
identifier nested_open;
@@
nested_open(...)
{
<+...
nonseekable_open(...)
...+>
}

@ open exists@
identifier open_f;
identifier i, f;
identifier open1.nested_open;
@@
int open_f(struct inode *i, struct file *f)
{
<+...
(
nonseekable_open(...)
|
nested_open(...)
)
...+>
}

@ read disable optional_qualifier exists @
identifier read_f;
identifier f, p, s, off;
type ssize_t, size_t, loff_t;
expression E;
identifier func;
@@
ssize_t read_f(struct file *f, char *p, size_t s, loff_t *off)
{
<+...
(
   *off = E
|
   *off += E
|
   func(..., off, ...)
|
   E = *off
)
...+>
}

@ read_no_fpos disable optional_qualifier exists @
identifier read_f;
identifier f, p, s, off;
type ssize_t, size_t, loff_t;
@@
ssize_t read_f(struct file *f, char *p, size_t s, loff_t *off)
{
... when != off
}

@ write @
identifier write_f;
identifier f, p, s, off;
type ssize_t, size_t, loff_t;
expression E;
identifier func;
@@
ssize_t write_f(struct file *f, const char *p, size_t s, loff_t *off)
{
<+...
(
  *off = E
|
  *off += E
|
  func(..., off, ...)
|
  E = *off
)
...+>
}

@ write_no_fpos @
identifier write_f;
identifier f, p, s, off;
type ssize_t, size_t, loff_t;
@@
ssize_t write_f(struct file *f, const char *p, size_t s, loff_t *off)
{
... when != off
}

@ fops0 @
identifier fops;
@@
struct file_operations fops = {
 ...
};

@ has_llseek depends on fops0 @
identifier fops0.fops;
identifier llseek_f;
@@
struct file_operations fops = {
...
 .llseek = llseek_f,
...
};

@ has_read depends on fops0 @
identifier fops0.fops;
identifier read_f;
@@
struct file_operations fops = {
...
 .read = read_f,
...
};

@ has_write depends on fops0 @
identifier fops0.fops;
identifier write_f;
@@
struct file_operations fops = {
...
 .write = write_f,
...
};

@ has_open depends on fops0 @
identifier fops0.fops;
identifier open_f;
@@
struct file_operations fops = {
...
 .open = open_f,
...
};

// use no_llseek if we call nonseekable_open
////////////////////////////////////////////
@ nonseekable1 depends on !has_llseek && has_open @
identifier fops0.fops;
identifier nso ~= "nonseekable_open";
@@
struct file_operations fops = {
...  .open = nso, ...
+.llseek = no_llseek, /* nonseekable */
};

@ nonseekable2 depends on !has_llseek @
identifier fops0.fops;
identifier open.open_f;
@@
struct file_operations fops = {
...  .open = open_f, ...
+.llseek = no_llseek, /* open uses nonseekable */
};

// use seq_lseek for sequential files
/////////////////////////////////////
@ seq depends on !has_llseek @
identifier fops0.fops;
identifier sr ~= "seq_read";
@@
struct file_operations fops = {
...  .read = sr, ...
+.llseek = seq_lseek, /* we have seq_read */
};

// use default_llseek if there is a readdir
///////////////////////////////////////////
@ fops1 depends on !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
identifier readdir_e;
@@
// any other fop is used that changes pos
struct file_operations fops = {
... .readdir = readdir_e, ...
+.llseek = default_llseek, /* readdir is present */
};

// use default_llseek if at least one of read/write touches f_pos
/////////////////////////////////////////////////////////////////
@ fops2 depends on !fops1 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
identifier read.read_f;
@@
// read fops use offset
struct file_operations fops = {
... .read = read_f, ...
+.llseek = default_llseek, /* read accesses f_pos */
};

@ fops3 depends on !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
identifier write.write_f;
@@
// write fops use offset
struct file_operations fops = {
... .write = write_f, ...
+	.llseek = default_llseek, /* write accesses f_pos */
};

// Use noop_llseek if neither read nor write accesses f_pos
///////////////////////////////////////////////////////////

@ fops4 depends on !fops1 && !fops2 && !fops3 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
identifier read_no_fpos.read_f;
identifier write_no_fpos.write_f;
@@
// write fops use offset
struct file_operations fops = {
...
 .write = write_f,
 .read = read_f,
...
+.llseek = noop_llseek, /* read and write both use no f_pos */
};

@ depends on has_write && !has_read && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
identifier write_no_fpos.write_f;
@@
struct file_operations fops = {
... .write = write_f, ...
+.llseek = noop_llseek, /* write uses no f_pos */
};

@ depends on has_read && !has_write && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
identifier read_no_fpos.read_f;
@@
struct file_operations fops = {
... .read = read_f, ...
+.llseek = noop_llseek, /* read uses no f_pos */
};

@ depends on !has_read && !has_write && !fops1 && !fops2 && !has_llseek && !nonseekable1 && !nonseekable2 && !seq @
identifier fops0.fops;
@@
struct file_operations fops = {
...
+.llseek = noop_llseek, /* no read or write fn */
};
===== End semantic patch =====

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Cc: Julia Lawall <julia@diku.dk>
Cc: Christoph Hellwig <hch@infradead.org>
2010-10-15 15:53:27 +02:00

460 lines
12 KiB
C

/*****************************************************************************
* USBLCD Kernel Driver *
* Version 1.05 *
* (C) 2005 Georges Toth <g.toth@e-biz.lu> *
* *
* This file is licensed under the GPL. See COPYING in the package. *
* Based on usb-skeleton.c 2.0 by Greg Kroah-Hartman (greg@kroah.com) *
* *
* *
* 28.02.05 Complete rewrite of the original usblcd.c driver, *
* based on usb_skeleton.c. *
* This new driver allows more than one USB-LCD to be connected *
* and controlled, at once *
*****************************************************************************/
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/errno.h>
#include <linux/mutex.h>
#include <asm/uaccess.h>
#include <linux/usb.h>
#define DRIVER_VERSION "USBLCD Driver Version 1.05"
#define USBLCD_MINOR 144
#define IOCTL_GET_HARD_VERSION 1
#define IOCTL_GET_DRV_VERSION 2
static DEFINE_MUTEX(lcd_mutex);
static const struct usb_device_id id_table[] = {
{ .idVendor = 0x10D2, .match_flags = USB_DEVICE_ID_MATCH_VENDOR, },
{ },
};
MODULE_DEVICE_TABLE (usb, id_table);
static DEFINE_MUTEX(open_disc_mutex);
struct usb_lcd {
struct usb_device * udev; /* init: probe_lcd */
struct usb_interface * interface; /* the interface for this device */
unsigned char * bulk_in_buffer; /* the buffer to receive data */
size_t bulk_in_size; /* the size of the receive buffer */
__u8 bulk_in_endpointAddr; /* the address of the bulk in endpoint */
__u8 bulk_out_endpointAddr; /* the address of the bulk out endpoint */
struct kref kref;
struct semaphore limit_sem; /* to stop writes at full throttle from
* using up all RAM */
struct usb_anchor submitted; /* URBs to wait for before suspend */
};
#define to_lcd_dev(d) container_of(d, struct usb_lcd, kref)
#define USB_LCD_CONCURRENT_WRITES 5
static struct usb_driver lcd_driver;
static void lcd_delete(struct kref *kref)
{
struct usb_lcd *dev = to_lcd_dev(kref);
usb_put_dev(dev->udev);
kfree (dev->bulk_in_buffer);
kfree (dev);
}
static int lcd_open(struct inode *inode, struct file *file)
{
struct usb_lcd *dev;
struct usb_interface *interface;
int subminor, r;
mutex_lock(&lcd_mutex);
subminor = iminor(inode);
interface = usb_find_interface(&lcd_driver, subminor);
if (!interface) {
mutex_unlock(&lcd_mutex);
err ("USBLCD: %s - error, can't find device for minor %d",
__func__, subminor);
return -ENODEV;
}
mutex_lock(&open_disc_mutex);
dev = usb_get_intfdata(interface);
if (!dev) {
mutex_unlock(&open_disc_mutex);
mutex_unlock(&lcd_mutex);
return -ENODEV;
}
/* increment our usage count for the device */
kref_get(&dev->kref);
mutex_unlock(&open_disc_mutex);
/* grab a power reference */
r = usb_autopm_get_interface(interface);
if (r < 0) {
kref_put(&dev->kref, lcd_delete);
mutex_unlock(&lcd_mutex);
return r;
}
/* save our object in the file's private structure */
file->private_data = dev;
mutex_unlock(&lcd_mutex);
return 0;
}
static int lcd_release(struct inode *inode, struct file *file)
{
struct usb_lcd *dev;
dev = file->private_data;
if (dev == NULL)
return -ENODEV;
/* decrement the count on our device */
usb_autopm_put_interface(dev->interface);
kref_put(&dev->kref, lcd_delete);
return 0;
}
static ssize_t lcd_read(struct file *file, char __user * buffer, size_t count, loff_t *ppos)
{
struct usb_lcd *dev;
int retval = 0;
int bytes_read;
dev = file->private_data;
/* do a blocking bulk read to get data from the device */
retval = usb_bulk_msg(dev->udev,
usb_rcvbulkpipe(dev->udev, dev->bulk_in_endpointAddr),
dev->bulk_in_buffer,
min(dev->bulk_in_size, count),
&bytes_read, 10000);
/* if the read was successful, copy the data to userspace */
if (!retval) {
if (copy_to_user(buffer, dev->bulk_in_buffer, bytes_read))
retval = -EFAULT;
else
retval = bytes_read;
}
return retval;
}
static long lcd_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
struct usb_lcd *dev;
u16 bcdDevice;
char buf[30];
dev = file->private_data;
if (dev == NULL)
return -ENODEV;
switch (cmd) {
case IOCTL_GET_HARD_VERSION:
mutex_lock(&lcd_mutex);
bcdDevice = le16_to_cpu((dev->udev)->descriptor.bcdDevice);
sprintf(buf,"%1d%1d.%1d%1d",
(bcdDevice & 0xF000)>>12,
(bcdDevice & 0xF00)>>8,
(bcdDevice & 0xF0)>>4,
(bcdDevice & 0xF));
mutex_unlock(&lcd_mutex);
if (copy_to_user((void __user *)arg,buf,strlen(buf))!=0)
return -EFAULT;
break;
case IOCTL_GET_DRV_VERSION:
sprintf(buf,DRIVER_VERSION);
if (copy_to_user((void __user *)arg,buf,strlen(buf))!=0)
return -EFAULT;
break;
default:
return -ENOTTY;
break;
}
return 0;
}
static void lcd_write_bulk_callback(struct urb *urb)
{
struct usb_lcd *dev;
int status = urb->status;
dev = urb->context;
/* sync/async unlink faults aren't errors */
if (status &&
!(status == -ENOENT ||
status == -ECONNRESET ||
status == -ESHUTDOWN)) {
dbg("USBLCD: %s - nonzero write bulk status received: %d",
__func__, status);
}
/* free up our allocated buffer */
usb_free_coherent(urb->dev, urb->transfer_buffer_length,
urb->transfer_buffer, urb->transfer_dma);
up(&dev->limit_sem);
}
static ssize_t lcd_write(struct file *file, const char __user * user_buffer, size_t count, loff_t *ppos)
{
struct usb_lcd *dev;
int retval = 0, r;
struct urb *urb = NULL;
char *buf = NULL;
dev = file->private_data;
/* verify that we actually have some data to write */
if (count == 0)
goto exit;
r = down_interruptible(&dev->limit_sem);
if (r < 0)
return -EINTR;
/* create a urb, and a buffer for it, and copy the data to the urb */
urb = usb_alloc_urb(0, GFP_KERNEL);
if (!urb) {
retval = -ENOMEM;
goto err_no_buf;
}
buf = usb_alloc_coherent(dev->udev, count, GFP_KERNEL, &urb->transfer_dma);
if (!buf) {
retval = -ENOMEM;
goto error;
}
if (copy_from_user(buf, user_buffer, count)) {
retval = -EFAULT;
goto error;
}
/* initialize the urb properly */
usb_fill_bulk_urb(urb, dev->udev,
usb_sndbulkpipe(dev->udev, dev->bulk_out_endpointAddr),
buf, count, lcd_write_bulk_callback, dev);
urb->transfer_flags |= URB_NO_TRANSFER_DMA_MAP;
usb_anchor_urb(urb, &dev->submitted);
/* send the data out the bulk port */
retval = usb_submit_urb(urb, GFP_KERNEL);
if (retval) {
err("USBLCD: %s - failed submitting write urb, error %d", __func__, retval);
goto error_unanchor;
}
/* release our reference to this urb, the USB core will eventually free it entirely */
usb_free_urb(urb);
exit:
return count;
error_unanchor:
usb_unanchor_urb(urb);
error:
usb_free_coherent(dev->udev, count, buf, urb->transfer_dma);
usb_free_urb(urb);
err_no_buf:
up(&dev->limit_sem);
return retval;
}
static const struct file_operations lcd_fops = {
.owner = THIS_MODULE,
.read = lcd_read,
.write = lcd_write,
.open = lcd_open,
.unlocked_ioctl = lcd_ioctl,
.release = lcd_release,
.llseek = noop_llseek,
};
/*
* usb class driver info in order to get a minor number from the usb core,
* and to have the device registered with the driver core
*/
static struct usb_class_driver lcd_class = {
.name = "lcd%d",
.fops = &lcd_fops,
.minor_base = USBLCD_MINOR,
};
static int lcd_probe(struct usb_interface *interface, const struct usb_device_id *id)
{
struct usb_lcd *dev = NULL;
struct usb_host_interface *iface_desc;
struct usb_endpoint_descriptor *endpoint;
size_t buffer_size;
int i;
int retval = -ENOMEM;
/* allocate memory for our device state and initialize it */
dev = kzalloc(sizeof(*dev), GFP_KERNEL);
if (dev == NULL) {
err("Out of memory");
goto error;
}
kref_init(&dev->kref);
sema_init(&dev->limit_sem, USB_LCD_CONCURRENT_WRITES);
init_usb_anchor(&dev->submitted);
dev->udev = usb_get_dev(interface_to_usbdev(interface));
dev->interface = interface;
if (le16_to_cpu(dev->udev->descriptor.idProduct) != 0x0001) {
dev_warn(&interface->dev, "USBLCD model not supported.\n");
retval = -ENODEV;
goto error;
}
/* set up the endpoint information */
/* use only the first bulk-in and bulk-out endpoints */
iface_desc = interface->cur_altsetting;
for (i = 0; i < iface_desc->desc.bNumEndpoints; ++i) {
endpoint = &iface_desc->endpoint[i].desc;
if (!dev->bulk_in_endpointAddr &&
usb_endpoint_is_bulk_in(endpoint)) {
/* we found a bulk in endpoint */
buffer_size = le16_to_cpu(endpoint->wMaxPacketSize);
dev->bulk_in_size = buffer_size;
dev->bulk_in_endpointAddr = endpoint->bEndpointAddress;
dev->bulk_in_buffer = kmalloc(buffer_size, GFP_KERNEL);
if (!dev->bulk_in_buffer) {
err("Could not allocate bulk_in_buffer");
goto error;
}
}
if (!dev->bulk_out_endpointAddr &&
usb_endpoint_is_bulk_out(endpoint)) {
/* we found a bulk out endpoint */
dev->bulk_out_endpointAddr = endpoint->bEndpointAddress;
}
}
if (!(dev->bulk_in_endpointAddr && dev->bulk_out_endpointAddr)) {
err("Could not find both bulk-in and bulk-out endpoints");
goto error;
}
/* save our data pointer in this interface device */
usb_set_intfdata(interface, dev);
/* we can register the device now, as it is ready */
retval = usb_register_dev(interface, &lcd_class);
if (retval) {
/* something prevented us from registering this driver */
err("Not able to get a minor for this device.");
usb_set_intfdata(interface, NULL);
goto error;
}
i = le16_to_cpu(dev->udev->descriptor.bcdDevice);
dev_info(&interface->dev, "USBLCD Version %1d%1d.%1d%1d found "
"at address %d\n", (i & 0xF000)>>12, (i & 0xF00)>>8,
(i & 0xF0)>>4,(i & 0xF), dev->udev->devnum);
/* let the user know what node this device is now attached to */
dev_info(&interface->dev, "USB LCD device now attached to USBLCD-%d\n",
interface->minor);
return 0;
error:
if (dev)
kref_put(&dev->kref, lcd_delete);
return retval;
}
static void lcd_draw_down(struct usb_lcd *dev)
{
int time;
time = usb_wait_anchor_empty_timeout(&dev->submitted, 1000);
if (!time)
usb_kill_anchored_urbs(&dev->submitted);
}
static int lcd_suspend(struct usb_interface *intf, pm_message_t message)
{
struct usb_lcd *dev = usb_get_intfdata(intf);
if (!dev)
return 0;
lcd_draw_down(dev);
return 0;
}
static int lcd_resume (struct usb_interface *intf)
{
return 0;
}
static void lcd_disconnect(struct usb_interface *interface)
{
struct usb_lcd *dev;
int minor = interface->minor;
mutex_lock(&open_disc_mutex);
dev = usb_get_intfdata(interface);
usb_set_intfdata(interface, NULL);
mutex_unlock(&open_disc_mutex);
/* give back our minor */
usb_deregister_dev(interface, &lcd_class);
/* decrement our usage count */
kref_put(&dev->kref, lcd_delete);
dev_info(&interface->dev, "USB LCD #%d now disconnected\n", minor);
}
static struct usb_driver lcd_driver = {
.name = "usblcd",
.probe = lcd_probe,
.disconnect = lcd_disconnect,
.suspend = lcd_suspend,
.resume = lcd_resume,
.id_table = id_table,
.supports_autosuspend = 1,
};
static int __init usb_lcd_init(void)
{
int result;
result = usb_register(&lcd_driver);
if (result)
err("usb_register failed. Error number %d", result);
return result;
}
static void __exit usb_lcd_exit(void)
{
usb_deregister(&lcd_driver);
}
module_init(usb_lcd_init);
module_exit(usb_lcd_exit);
MODULE_AUTHOR("Georges Toth <g.toth@e-biz.lu>");
MODULE_DESCRIPTION(DRIVER_VERSION);
MODULE_LICENSE("GPL");