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freebsd/sys/dev/io/iodev.c
Ed Schouten cacdd70cc7 Remove D_NEEDGIANT from io(4).
There is no need to mark this device node to use Giant. The only
architectures that use io(4) (i386 and amd64) only change a flag in
td->td_frame, which is only accessed by curthread.

Apart from this change, I think some fishy things may happen when using
/dev/io in multithreaded applications. I haven't tested, but looking at
the code, the flag doesn't get cleared when close() is called from
another thread, but this may not be this important.

I'm not removing D_NEEDGIANT from mem(4), because this driver isn't
Giant safe at all (it calls GIANT_REQUIRED).
2008-08-08 13:43:56 +00:00

90 lines
2.3 KiB
C

/*-
* Copyright (c) 2004 Mark R V Murray
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer
* in this position and unchanged.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHORS ``AS IS'' AND ANY EXPRESS OR
* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
* IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
* THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/conf.h>
#include <sys/fcntl.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/malloc.h>
#include <sys/module.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/signalvar.h>
#include <sys/systm.h>
#include <sys/uio.h>
#include <machine/specialreg.h>
#include <vm/vm.h>
#include <vm/pmap.h>
#include <machine/iodev.h>
static struct cdev *iodev;
static struct cdevsw io_cdevsw = {
.d_version = D_VERSION,
.d_open = ioopen,
.d_close = ioclose,
.d_name = "io",
};
/* ARGSUSED */
static int
io_modevent(module_t mod __unused, int type, void *data __unused)
{
switch(type) {
case MOD_LOAD:
if (bootverbose)
printf("io: <I/O>\n");
iodev = make_dev(&io_cdevsw, 0,
UID_ROOT, GID_WHEEL, 0600, "io");
break;
case MOD_UNLOAD:
destroy_dev(iodev);
break;
case MOD_SHUTDOWN:
break;
default:
return(EOPNOTSUPP);
break;
}
return (0);
}
DEV_MODULE(io, io_modevent, NULL);
MODULE_VERSION(io, 1);