linux/arch/um/drivers/null.c
Jeff Dike 730760e90a [PATCH] uml: locking documentation
Some locking documentation and a cleanup.  uml_exitcode is copied into a local
before sprintf sees it, in case sprintf does anything non-atomic with it.

The rest are comments about why certain globals don't need any kind of
locking.

Signed-off-by: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-09-29 09:18:04 -07:00

58 lines
1.3 KiB
C

/*
* Copyright (C) 2002 Jeff Dike (jdike@karaya.com)
* Licensed under the GPL
*/
#include <stdlib.h>
#include <errno.h>
#include "chan_user.h"
#include "os.h"
/* This address is used only as a unique identifer */
static int null_chan;
static void *null_init(char *str, int device, const struct chan_opts *opts)
{
return(&null_chan);
}
static int null_open(int input, int output, int primary, void *d,
char **dev_out)
{
*dev_out = NULL;
return(os_open_file(DEV_NULL, of_rdwr(OPENFLAGS()), 0));
}
static int null_read(int fd, char *c_out, void *unused)
{
return(-ENODEV);
}
static void null_free(void *data)
{
}
const struct chan_ops null_ops = {
.type = "null",
.init = null_init,
.open = null_open,
.close = generic_close,
.read = null_read,
.write = generic_write,
.console_write = generic_console_write,
.window_size = generic_window_size,
.free = null_free,
.winch = 0,
};
/*
* Overrides for Emacs so that we follow Linus's tabbing style.
* Emacs will notice this stuff at the end of the file and automatically
* adjust the settings for this buffer only. This must remain at the end
* of the file.
* ---------------------------------------------------------------------------
* Local variables:
* c-file-style: "linux"
* End:
*/