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Turn rtlx upside down.
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 o Coding style
 o Race condition on open
 o Switch to dynamic major
 o Header file cleanup
    
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
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Ralf Baechle committed Nov 7, 2005
1 parent 0b154bb commit afc4841
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Showing 2 changed files with 105 additions and 120 deletions.
197 changes: 93 additions & 104 deletions arch/mips/kernel/rtlx.c
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Original file line number Diff line number Diff line change
Expand Up @@ -20,52 +20,51 @@
#include <linux/module.h>
#include <linux/fs.h>
#include <linux/init.h>
#include <asm/uaccess.h>
#include <linux/slab.h>
#include <linux/list.h>
#include <linux/vmalloc.h>
#include <linux/elf.h>
#include <linux/seq_file.h>
#include <linux/syscalls.h>
#include <linux/moduleloader.h>
#include <linux/interrupt.h>
#include <linux/poll.h>
#include <linux/sched.h>
#include <linux/wait.h>
#include <asm/mipsmtregs.h>
#include <asm/cacheflush.h>
#include <asm/atomic.h>
#include <asm/bitops.h>
#include <asm/cpu.h>
#include <asm/processor.h>
#include <asm/system.h>
#include <asm/rtlx.h>
#include <asm/uaccess.h>

#define RTLX_MAJOR 64
#define RTLX_TARG_VPE 1

struct rtlx_info *rtlx;
static struct rtlx_info *rtlx;
static int major;
static char module_name[] = "rtlx";
static inline int spacefree(int read, int write, int size);
static struct irqaction irq;
static int irq_num;

static inline int spacefree(int read, int write, int size)
{
if (read == write) {
/*
* never fill the buffer completely, so indexes are always
* equal if empty and only empty, or !equal if data available
*/
return size - 1;
}

return ((read + size - write) % size) - 1;
}

static struct chan_waitqueues {
wait_queue_head_t rt_queue;
wait_queue_head_t lx_queue;
} channel_wqs[RTLX_CHANNELS];

static struct irqaction irq;
static int irq_num;

extern void *vpe_get_shared(int index);

static void rtlx_dispatch(struct pt_regs *regs)
{
do_IRQ(MIPSCPU_INT_BASE + MIPS_CPU_RTLX_IRQ, regs);
}

irqreturn_t rtlx_interrupt(int irq, void *dev_id, struct pt_regs *regs)
static irqreturn_t rtlx_interrupt(int irq, void *dev_id, struct pt_regs *regs)
{
irqreturn_t r = IRQ_HANDLED;
int i;

for (i = 0; i < RTLX_CHANNELS; i++) {
Expand All @@ -75,30 +74,7 @@ irqreturn_t rtlx_interrupt(int irq, void *dev_id, struct pt_regs *regs)
wake_up_interruptible(&channel_wqs[i].lx_queue);
}

return r;
}

void dump_rtlx(void)
{
int i;

printk("id 0x%lx state %d\n", rtlx->id, rtlx->state);

for (i = 0; i < RTLX_CHANNELS; i++) {
struct rtlx_channel *chan = &rtlx->channel[i];

printk(" rt_state %d lx_state %d buffer_size %d\n",
chan->rt_state, chan->lx_state, chan->buffer_size);

printk(" rt_read %d rt_write %d\n",
chan->rt_read, chan->rt_write);

printk(" lx_read %d lx_write %d\n",
chan->lx_read, chan->lx_write);

printk(" rt_buffer <%s>\n", chan->rt_buffer);
printk(" lx_buffer <%s>\n", chan->lx_buffer);
}
return IRQ_HANDLED;
}

/* call when we have the address of the shared structure from the SP side. */
Expand All @@ -108,7 +84,7 @@ static int rtlx_init(struct rtlx_info *rtlxi)

if (rtlxi->id != RTLX_ID) {
printk(KERN_WARNING "no valid RTLX id at 0x%p\n", rtlxi);
return (-ENOEXEC);
return -ENOEXEC;
}

/* initialise the wait queues */
Expand All @@ -120,9 +96,8 @@ static int rtlx_init(struct rtlx_info *rtlxi)
/* set up for interrupt handling */
memset(&irq, 0, sizeof(struct irqaction));

if (cpu_has_vint) {
if (cpu_has_vint)
set_vi_handler(MIPS_CPU_RTLX_IRQ, rtlx_dispatch);
}

irq_num = MIPSCPU_INT_BASE + MIPS_CPU_RTLX_IRQ;
irq.handler = rtlx_interrupt;
Expand All @@ -132,7 +107,8 @@ static int rtlx_init(struct rtlx_info *rtlxi)
setup_irq(irq_num, &irq);

rtlx = rtlxi;
return (0);

return 0;
}

/* only allow one open process at a time to open each channel */
Expand All @@ -147,36 +123,36 @@ static int rtlx_open(struct inode *inode, struct file *filp)
if (rtlx == NULL) {
struct rtlx_info **p;
if( (p = vpe_get_shared(RTLX_TARG_VPE)) == NULL) {
printk(" vpe_get_shared is NULL. Has an SP program been loaded?\n");
return (-EFAULT);
printk(KERN_ERR "vpe_get_shared is NULL. "
"Has an SP program been loaded?\n");
return -EFAULT;
}

if (*p == NULL) {
printk(" vpe_shared %p %p\n", p, *p);
return (-EFAULT);
printk(KERN_ERR "vpe_shared %p %p\n", p, *p);
return -EFAULT;
}

if ((ret = rtlx_init(*p)) < 0)
return (ret);
return ret;
}

chan = &rtlx->channel[minor];

/* already open? */
if (chan->lx_state == RTLX_STATE_OPENED)
return (-EBUSY);
if (test_and_set_bit(RTLX_STATE_OPENED, &chan->lx_state))
return -EBUSY;

chan->lx_state = RTLX_STATE_OPENED;
return (0);
return 0;
}

static int rtlx_release(struct inode *inode, struct file *filp)
{
int minor;
int minor = MINOR(inode->i_rdev);

minor = MINOR(inode->i_rdev);
rtlx->channel[minor].lx_state = RTLX_STATE_UNUSED;
return (0);
clear_bit(RTLX_STATE_OPENED, &rtlx->channel[minor].lx_state);
smp_mb__after_clear_bit();

return 0;
}

static unsigned int rtlx_poll(struct file *file, poll_table * wait)
Expand All @@ -199,12 +175,13 @@ static unsigned int rtlx_poll(struct file *file, poll_table * wait)
if (spacefree(chan->rt_read, chan->rt_write, chan->buffer_size))
mask |= POLLOUT | POLLWRNORM;

return (mask);
return mask;
}

static ssize_t rtlx_read(struct file *file, char __user * buffer, size_t count,
loff_t * ppos)
{
unsigned long failed;
size_t fl = 0L;
int minor;
struct rtlx_channel *lx;
Expand All @@ -216,7 +193,7 @@ static ssize_t rtlx_read(struct file *file, char __user * buffer, size_t count,
/* data available? */
if (lx->lx_write == lx->lx_read) {
if (file->f_flags & O_NONBLOCK)
return (0); // -EAGAIN makes cat whinge
return 0; /* -EAGAIN makes cat whinge */

/* go to sleep */
add_wait_queue(&channel_wqs[minor].lx_queue, &wait);
Expand All @@ -232,39 +209,39 @@ static ssize_t rtlx_read(struct file *file, char __user * buffer, size_t count,
}

/* find out how much in total */
count = min( count,
(size_t)(lx->lx_write + lx->buffer_size - lx->lx_read) % lx->buffer_size);
count = min(count,
(size_t)(lx->lx_write + lx->buffer_size - lx->lx_read) % lx->buffer_size);

/* then how much from the read pointer onwards */
fl = min( count, (size_t)lx->buffer_size - lx->lx_read);
fl = min(count, (size_t)lx->buffer_size - lx->lx_read);

copy_to_user (buffer, &lx->lx_buffer[lx->lx_read], fl);
failed = copy_to_user (buffer, &lx->lx_buffer[lx->lx_read], fl);
if (failed) {
count = fl - failed;
goto out;
}

/* and if there is anything left at the beginning of the buffer */
if ( count - fl )
copy_to_user (buffer + fl, lx->lx_buffer, count - fl);
if (count - fl) {
failed = copy_to_user (buffer + fl, lx->lx_buffer, count - fl);
if (failed) {
count -= failed;
goto out;
}
}

out:
/* update the index */
lx->lx_read += count;
lx->lx_read %= lx->buffer_size;

return (count);
}

static inline int spacefree(int read, int write, int size)
{
if (read == write) {
/* never fill the buffer completely, so indexes are always equal if empty
and only empty, or !equal if data available */
return (size - 1);
}

return ((read + size - write) % size) - 1;
return count;
}

static ssize_t rtlx_write(struct file *file, const char __user * buffer,
size_t count, loff_t * ppos)
{
unsigned long failed;
int minor;
struct rtlx_channel *rt;
size_t fl;
Expand All @@ -277,7 +254,7 @@ static ssize_t rtlx_write(struct file *file, const char __user * buffer,
if (!spacefree(rt->rt_read, rt->rt_write, rt->buffer_size)) {

if (file->f_flags & O_NONBLOCK)
return (-EAGAIN);
return -EAGAIN;

add_wait_queue(&channel_wqs[minor].rt_queue, &wait);
set_current_state(TASK_INTERRUPTIBLE);
Expand All @@ -290,52 +267,64 @@ static ssize_t rtlx_write(struct file *file, const char __user * buffer,
}

/* total number of bytes to copy */
count = min( count, (size_t)spacefree(rt->rt_read, rt->rt_write, rt->buffer_size) );
count = min(count, (size_t)spacefree(rt->rt_read, rt->rt_write, rt->buffer_size) );

/* first bit from write pointer to the end of the buffer, or count */
fl = min(count, (size_t) rt->buffer_size - rt->rt_write);

copy_from_user(&rt->rt_buffer[rt->rt_write], buffer, fl);
failed = copy_from_user(&rt->rt_buffer[rt->rt_write], buffer, fl);
if (failed) {
count = fl - failed;
goto out;
}

/* if there's any left copy to the beginning of the buffer */
if( count - fl )
copy_from_user(rt->rt_buffer, buffer + fl, count - fl);
if (count - fl) {
failed = copy_from_user(rt->rt_buffer, buffer + fl, count - fl);
if (failed) {
count -= failed;
goto out;
}
}

out:
rt->rt_write += count;
rt->rt_write %= rt->buffer_size;

return(count);
return count;
}

static struct file_operations rtlx_fops = {
.owner = THIS_MODULE,
.open = rtlx_open,
.release = rtlx_release,
.write = rtlx_write,
.read = rtlx_read,
.poll = rtlx_poll
.owner = THIS_MODULE,
.open = rtlx_open,
.release = rtlx_release,
.write = rtlx_write,
.read = rtlx_read,
.poll = rtlx_poll
};

static int rtlx_module_init(void)
static char register_chrdev_failed[] __initdata =
KERN_ERR "rtlx_module_init: unable to register device\n";

static int __init rtlx_module_init(void)
{
if ((major = register_chrdev(RTLX_MAJOR, module_name, &rtlx_fops)) < 0) {
printk("rtlx_module_init: unable to register device\n");
return (-EBUSY);
major = register_chrdev(0, module_name, &rtlx_fops);
if (major < 0) {
printk(register_chrdev_failed);
return major;
}

if (major == 0)
major = RTLX_MAJOR;

return (0);
return 0;
}

static void rtlx_module_exit(void)
static void __exit rtlx_module_exit(void)
{
unregister_chrdev(major, module_name);
}

module_init(rtlx_module_init);
module_exit(rtlx_module_exit);

MODULE_DESCRIPTION("MIPS RTLX");
MODULE_AUTHOR("Elizabeth Clarke, MIPS Technologies, Inc");
MODULE_AUTHOR("Elizabeth Clarke, MIPS Technologies, Inc.");
MODULE_LICENSE("GPL");
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