linux/fs/fifo.c
Alexey Dobriyan e8edc6e03a Detach sched.h from mm.h
First thing mm.h does is including sched.h solely for can_do_mlock() inline
function which has "current" dereference inside. By dealing with can_do_mlock()
mm.h can be detached from sched.h which is good. See below, why.

This patch
a) removes unconditional inclusion of sched.h from mm.h
b) makes can_do_mlock() normal function in mm/mlock.c
c) exports can_do_mlock() to not break compilation
d) adds sched.h inclusions back to files that were getting it indirectly.
e) adds less bloated headers to some files (asm/signal.h, jiffies.h) that were
   getting them indirectly

Net result is:
a) mm.h users would get less code to open, read, preprocess, parse, ... if
   they don't need sched.h
b) sched.h stops being dependency for significant number of files:
   on x86_64 allmodconfig touching sched.h results in recompile of 4083 files,
   after patch it's only 3744 (-8.3%).

Cross-compile tested on

	all arm defconfigs, all mips defconfigs, all powerpc defconfigs,
	alpha alpha-up
	arm
	i386 i386-up i386-defconfig i386-allnoconfig
	ia64 ia64-up
	m68k
	mips
	parisc parisc-up
	powerpc powerpc-up
	s390 s390-up
	sparc sparc-up
	sparc64 sparc64-up
	um-x86_64
	x86_64 x86_64-up x86_64-defconfig x86_64-allnoconfig

as well as my two usual configs.

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2007-05-21 09:18:19 -07:00

155 lines
3.1 KiB
C

/*
* linux/fs/fifo.c
*
* written by Paul H. Hargrove
*
* Fixes:
* 10-06-1999, AV: fixed OOM handling in fifo_open(), moved
* initialization there, switched to external
* allocation of pipe_inode_info.
*/
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/fs.h>
#include <linux/sched.h>
#include <linux/pipe_fs_i.h>
static void wait_for_partner(struct inode* inode, unsigned int *cnt)
{
int cur = *cnt;
while (cur == *cnt) {
pipe_wait(inode->i_pipe);
if (signal_pending(current))
break;
}
}
static void wake_up_partner(struct inode* inode)
{
wake_up_interruptible(&inode->i_pipe->wait);
}
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 1:
/*
* 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_fifo_fops;
pipe->r_counter++;
if (pipe->readers++ == 0)
wake_up_partner(inode);
if (!pipe->writers) {
if ((filp->f_flags & O_NONBLOCK)) {
/* suppress POLLHUP until we have
* seen a writer */
filp->f_version = pipe->w_counter;
} else
{
wait_for_partner(inode, &pipe->w_counter);
if(signal_pending(current))
goto err_rd;
}
}
break;
case 2:
/*
* 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) && !pipe->readers)
goto err;
filp->f_op = &write_fifo_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 3:
/*
* 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_fifo_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;
}
/* Ok! */
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;
}
/*
* Dummy default file-operations: the only thing this does
* is contain the open that then fills in the correct operations
* depending on the access mode of the file...
*/
const struct file_operations def_fifo_fops = {
.open = fifo_open, /* will set read or write pipe_fops */
};