static int fifo_open(struct inode *inode, struct file *filp)
{
struct pipe_inode_info *pipe;
int ret;
mutex_lock(&inode->i_mutex);
pipe = inode->i_pipe;
if (!pipe) {
ret = -ENOMEM;
pipe = alloc_pipe_info(inode);
if (!pipe)
goto err_nocleanup;
inode->i_pipe = pipe;
}
filp->f_version = 0;
/* We can only do regular read/write on fifos */
filp->f_mode &= (FMODE_READ | FMODE_WRITE);
switch (filp->f_mode) {
case FMODE_READ:
/*
* O_RDONLY
* POSIX.1 says that O_NONBLOCK means return with the FIFO
* opened, even when there is no process writing the FIFO.
*/
filp->f_op = &read_pipefifo_fops;
pipe->r_counter++;
if (atomic_inc_return(&pipe->readers) == 1)
wake_up_partner(inode);
if (!atomic_read(&pipe->writers)) {
if ((filp->f_flags & O_NONBLOCK)) {
/* suppress POLLHUP until we have
* seen a writer */
filp->f_version = pipe->w_counter;
} else {
if (wait_for_partner(inode, &pipe->w_counter))
goto err_rd;
}
}
break;
case FMODE_WRITE:
/*
* O_WRONLY
* POSIX.1 says that O_NONBLOCK means return -1 with
* errno=ENXIO when there is no process reading the FIFO.
*/
ret = -ENXIO;
if ((filp->f_flags & O_NONBLOCK) && !atomic_read(&pipe->readers))
goto err;
filp->f_op = &write_pipefifo_fops;
pipe->w_counter++;
if (atomic_inc_return(&pipe->writers) == 1)
wake_up_partner(inode);
if (!atomic_read(&pipe->readers)) {
if (wait_for_partner(inode, &pipe->r_counter))
goto err_wr;
}
break;
case FMODE_READ | FMODE_WRITE:
/*
* O_RDWR
* POSIX.1 leaves this case "undefined" when O_NONBLOCK is set.
* This implementation will NEVER block on a O_RDWR open, since
* the process can at least talk to itself.
*/
filp->f_op = &rdwr_pipefifo_fops;
atomic_inc(&pipe->readers);
atomic_inc(&pipe->writers);
pipe->r_counter++;
pipe->w_counter++;
if (atomic_read(&pipe->readers) == 1 || atomic_read(&pipe->writers) == 1)
wake_up_partner(inode);
break;
default:
ret = -EINVAL;
goto err;
}
/* Ok! */
mutex_unlock(&inode->i_mutex);
return 0;
err_rd:
if (atomic_dec_and_test(&pipe->readers))
wake_up_interruptible(&pipe->wait);
ret = -ERESTARTSYS;
goto err;
err_wr:
if (atomic_dec_and_test(&pipe->writers))
wake_up_interruptible(&pipe->wait);
ret = -ERESTARTSYS;
goto err;
err:
if (!atomic_read(&pipe->readers) && !atomic_read(&pipe->writers))
free_pipe_info(inode);
err_nocleanup:
mutex_unlock(&inode->i_mutex);
return ret;
}
static int fifo_open(struct inode *inode, struct file *filp)
{
struct pipe_inode_info *pipe;
int ret;
mutex_lock(&inode->i_mutex);
pipe = inode->i_pipe;
if (!pipe) {
ret = -ENOMEM;
pipe = alloc_pipe_info(inode);
if (!pipe)
goto err_nocleanup;
inode->i_pipe = pipe;
}
filp->f_version = 0;
/* */
filp->f_mode &= (FMODE_READ | FMODE_WRITE);
switch (filp->f_mode) {
case FMODE_READ:
/*
*/
filp->f_op = &read_pipefifo_fops;
pipe->r_counter++;
if (pipe->readers++ == 0)
wake_up_partner(inode);
if (!pipe->writers) {
if ((filp->f_flags & O_NONBLOCK)) {
/*
*/
filp->f_version = pipe->w_counter;
} else {
wait_for_partner(inode, &pipe->w_counter);
if(signal_pending(current))
goto err_rd;
}
}
break;
case FMODE_WRITE:
/*
*/
ret = -ENXIO;
if ((filp->f_flags & O_NONBLOCK) && !pipe->readers)
goto err;
filp->f_op = &write_pipefifo_fops;
pipe->w_counter++;
if (!pipe->writers++)
wake_up_partner(inode);
if (!pipe->readers) {
wait_for_partner(inode, &pipe->r_counter);
if (signal_pending(current))
goto err_wr;
}
break;
case FMODE_READ | FMODE_WRITE:
/*
*/
filp->f_op = &rdwr_pipefifo_fops;
pipe->readers++;
pipe->writers++;
pipe->r_counter++;
pipe->w_counter++;
if (pipe->readers == 1 || pipe->writers == 1)
wake_up_partner(inode);
break;
default:
ret = -EINVAL;
goto err;
}
/* */
mutex_unlock(&inode->i_mutex);
return 0;
err_rd:
if (!--pipe->readers)
wake_up_interruptible(&pipe->wait);
ret = -ERESTARTSYS;
goto err;
err_wr:
if (!--pipe->writers)
wake_up_interruptible(&pipe->wait);
ret = -ERESTARTSYS;
goto err;
err:
if (!pipe->readers && !pipe->writers)
free_pipe_info(inode);
err_nocleanup:
mutex_unlock(&inode->i_mutex);
return ret;
}
