kernel-fxtec-pro1x/sound/core/seq/oss/seq_oss.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

312 lines
7.3 KiB
C

/*
* OSS compatible sequencer driver
*
* registration of device and proc
*
* Copyright (C) 1998,99 Takashi Iwai <tiwai@suse.de>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#include <linux/init.h>
#include <linux/moduleparam.h>
#include <linux/mutex.h>
#include <sound/core.h>
#include <sound/minors.h>
#include <sound/initval.h>
#include "seq_oss_device.h"
#include "seq_oss_synth.h"
/*
* module option
*/
MODULE_AUTHOR("Takashi Iwai <tiwai@suse.de>");
MODULE_DESCRIPTION("OSS-compatible sequencer module");
MODULE_LICENSE("GPL");
/* Takashi says this is really only for sound-service-0-, but this is OK. */
MODULE_ALIAS_SNDRV_MINOR(SNDRV_MINOR_OSS_SEQUENCER);
MODULE_ALIAS_SNDRV_MINOR(SNDRV_MINOR_OSS_MUSIC);
#ifdef SNDRV_SEQ_OSS_DEBUG
module_param(seq_oss_debug, int, 0644);
MODULE_PARM_DESC(seq_oss_debug, "debug option");
int seq_oss_debug = 0;
#endif
/*
* prototypes
*/
static int register_device(void);
static void unregister_device(void);
#ifdef CONFIG_PROC_FS
static int register_proc(void);
static void unregister_proc(void);
#else
static inline int register_proc(void) { return 0; }
static inline void unregister_proc(void) {}
#endif
static int odev_open(struct inode *inode, struct file *file);
static int odev_release(struct inode *inode, struct file *file);
static ssize_t odev_read(struct file *file, char __user *buf, size_t count, loff_t *offset);
static ssize_t odev_write(struct file *file, const char __user *buf, size_t count, loff_t *offset);
static long odev_ioctl(struct file *file, unsigned int cmd, unsigned long arg);
static unsigned int odev_poll(struct file *file, poll_table * wait);
/*
* module interface
*/
static int __init alsa_seq_oss_init(void)
{
int rc;
static struct snd_seq_dev_ops ops = {
snd_seq_oss_synth_register,
snd_seq_oss_synth_unregister,
};
snd_seq_autoload_lock();
if ((rc = register_device()) < 0)
goto error;
if ((rc = register_proc()) < 0) {
unregister_device();
goto error;
}
if ((rc = snd_seq_oss_create_client()) < 0) {
unregister_proc();
unregister_device();
goto error;
}
if ((rc = snd_seq_device_register_driver(SNDRV_SEQ_DEV_ID_OSS, &ops,
sizeof(struct snd_seq_oss_reg))) < 0) {
snd_seq_oss_delete_client();
unregister_proc();
unregister_device();
goto error;
}
/* success */
snd_seq_oss_synth_init();
error:
snd_seq_autoload_unlock();
return rc;
}
static void __exit alsa_seq_oss_exit(void)
{
snd_seq_device_unregister_driver(SNDRV_SEQ_DEV_ID_OSS);
snd_seq_oss_delete_client();
unregister_proc();
unregister_device();
}
module_init(alsa_seq_oss_init)
module_exit(alsa_seq_oss_exit)
/*
* ALSA minor device interface
*/
static DEFINE_MUTEX(register_mutex);
static int
odev_open(struct inode *inode, struct file *file)
{
int level, rc;
if (iminor(inode) == SNDRV_MINOR_OSS_MUSIC)
level = SNDRV_SEQ_OSS_MODE_MUSIC;
else
level = SNDRV_SEQ_OSS_MODE_SYNTH;
mutex_lock(&register_mutex);
rc = snd_seq_oss_open(file, level);
mutex_unlock(&register_mutex);
return rc;
}
static int
odev_release(struct inode *inode, struct file *file)
{
struct seq_oss_devinfo *dp;
if ((dp = file->private_data) == NULL)
return 0;
snd_seq_oss_drain_write(dp);
mutex_lock(&register_mutex);
snd_seq_oss_release(dp);
mutex_unlock(&register_mutex);
return 0;
}
static ssize_t
odev_read(struct file *file, char __user *buf, size_t count, loff_t *offset)
{
struct seq_oss_devinfo *dp;
dp = file->private_data;
if (snd_BUG_ON(!dp))
return -ENXIO;
return snd_seq_oss_read(dp, buf, count);
}
static ssize_t
odev_write(struct file *file, const char __user *buf, size_t count, loff_t *offset)
{
struct seq_oss_devinfo *dp;
dp = file->private_data;
if (snd_BUG_ON(!dp))
return -ENXIO;
return snd_seq_oss_write(dp, buf, count, file);
}
static long
odev_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
struct seq_oss_devinfo *dp;
dp = file->private_data;
if (snd_BUG_ON(!dp))
return -ENXIO;
return snd_seq_oss_ioctl(dp, cmd, arg);
}
#ifdef CONFIG_COMPAT
#define odev_ioctl_compat odev_ioctl
#else
#define odev_ioctl_compat NULL
#endif
static unsigned int
odev_poll(struct file *file, poll_table * wait)
{
struct seq_oss_devinfo *dp;
dp = file->private_data;
if (snd_BUG_ON(!dp))
return -ENXIO;
return snd_seq_oss_poll(dp, file, wait);
}
/*
* registration of sequencer minor device
*/
static const struct file_operations seq_oss_f_ops =
{
.owner = THIS_MODULE,
.read = odev_read,
.write = odev_write,
.open = odev_open,
.release = odev_release,
.poll = odev_poll,
.unlocked_ioctl = odev_ioctl,
.compat_ioctl = odev_ioctl_compat,
.llseek = noop_llseek,
};
static int __init
register_device(void)
{
int rc;
mutex_lock(&register_mutex);
if ((rc = snd_register_oss_device(SNDRV_OSS_DEVICE_TYPE_SEQUENCER,
NULL, 0,
&seq_oss_f_ops, NULL,
SNDRV_SEQ_OSS_DEVNAME)) < 0) {
snd_printk(KERN_ERR "can't register device seq\n");
mutex_unlock(&register_mutex);
return rc;
}
if ((rc = snd_register_oss_device(SNDRV_OSS_DEVICE_TYPE_MUSIC,
NULL, 0,
&seq_oss_f_ops, NULL,
SNDRV_SEQ_OSS_DEVNAME)) < 0) {
snd_printk(KERN_ERR "can't register device music\n");
snd_unregister_oss_device(SNDRV_OSS_DEVICE_TYPE_SEQUENCER, NULL, 0);
mutex_unlock(&register_mutex);
return rc;
}
debug_printk(("device registered\n"));
mutex_unlock(&register_mutex);
return 0;
}
static void
unregister_device(void)
{
mutex_lock(&register_mutex);
debug_printk(("device unregistered\n"));
if (snd_unregister_oss_device(SNDRV_OSS_DEVICE_TYPE_MUSIC, NULL, 0) < 0)
snd_printk(KERN_ERR "error unregister device music\n");
if (snd_unregister_oss_device(SNDRV_OSS_DEVICE_TYPE_SEQUENCER, NULL, 0) < 0)
snd_printk(KERN_ERR "error unregister device seq\n");
mutex_unlock(&register_mutex);
}
/*
* /proc interface
*/
#ifdef CONFIG_PROC_FS
static struct snd_info_entry *info_entry;
static void
info_read(struct snd_info_entry *entry, struct snd_info_buffer *buf)
{
mutex_lock(&register_mutex);
snd_iprintf(buf, "OSS sequencer emulation version %s\n", SNDRV_SEQ_OSS_VERSION_STR);
snd_seq_oss_system_info_read(buf);
snd_seq_oss_synth_info_read(buf);
snd_seq_oss_midi_info_read(buf);
mutex_unlock(&register_mutex);
}
static int __init
register_proc(void)
{
struct snd_info_entry *entry;
entry = snd_info_create_module_entry(THIS_MODULE, SNDRV_SEQ_OSS_PROCNAME, snd_seq_root);
if (entry == NULL)
return -ENOMEM;
entry->content = SNDRV_INFO_CONTENT_TEXT;
entry->private_data = NULL;
entry->c.text.read = info_read;
if (snd_info_register(entry) < 0) {
snd_info_free_entry(entry);
return -ENOMEM;
}
info_entry = entry;
return 0;
}
static void
unregister_proc(void)
{
snd_info_free_entry(info_entry);
info_entry = NULL;
}
#endif /* CONFIG_PROC_FS */