freebsd-nq/sys/dev/streams/streams.c
Robert Watson 5e3f7694b1 Replace custom file descriptor array sleep lock constructed using a mutex
and flags with an sxlock.  This leads to a significant and measurable
performance improvement as a result of access to shared locking for
frequent lookup operations, reduced general overhead, and reduced overhead
in the event of contention.  All of these are imported for threaded
applications where simultaneous access to a shared file descriptor array
occurs frequently.  Kris has reported 2x-4x transaction rate improvements
on 8-core MySQL benchmarks; smaller improvements can be expected for many
workloads as a result of reduced overhead.

- Generally eliminate the distinction between "fast" and regular
  acquisisition of the filedesc lock; the plan is that they will now all
  be fast.  Change all locking instances to either shared or exclusive
  locks.

- Correct a bug (pointed out by kib) in fdfree() where previously msleep()
  was called without the mutex held; sx_sleep() is now always called with
  the sxlock held exclusively.

- Universally hold the struct file lock over changes to struct file,
  rather than the filedesc lock or no lock.  Always update the f_ops
  field last. A further memory barrier is required here in the future
  (discussed with jhb).

- Improve locking and reference management in linux_at(), which fails to
  properly acquire vnode references before using vnode pointers.  Annotate
  improper use of vn_fullpath(), which will be replaced at a future date.

In fcntl(), we conservatively acquire an exclusive lock, even though in
some cases a shared lock may be sufficient, which should be revisited.
The dropping of the filedesc lock in fdgrowtable() is no longer required
as the sxlock can be held over the sleep operation; we should consider
removing that (pointed out by attilio).

Tested by:	kris
Discussed with:	jhb, kris, attilio, jeff
2007-04-04 09:11:34 +00:00

357 lines
8.9 KiB
C

/*-
* Copyright (c) 1998 Mark Newton
* Copyright (c) 1994 Christos Zoulas
* Copyright (c) 1997 Todd Vierling
* 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.
* 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.
* 3. The names of the authors may not be used to endorse or promote products
* derived from this software without specific prior written permission
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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.
*
* Stolen from NetBSD /sys/compat/svr4/svr4_net.c. Pseudo-device driver
* skeleton produced from /usr/share/examples/drivers/make_pseudo_driver.sh
* in 3.0-980524-SNAP then hacked a bit (but probably not enough :-).
*
*/
#include <sys/cdefs.h>
__FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h> /* SYSINIT stuff */
#include <sys/conf.h> /* cdevsw stuff */
#include <sys/malloc.h> /* malloc region definitions */
#include <sys/file.h>
#include <sys/filedesc.h>
#include <sys/unistd.h>
#include <sys/fcntl.h>
#include <sys/socket.h>
#include <sys/protosw.h>
#include <sys/socketvar.h>
#include <sys/syscallsubr.h>
#include <sys/un.h>
#include <sys/domain.h>
#include <net/if.h>
#include <netinet/in.h>
#include <sys/proc.h>
#include <sys/uio.h>
#include <sys/sysproto.h>
#include <compat/svr4/svr4_types.h>
#include <compat/svr4/svr4_util.h>
#include <compat/svr4/svr4_signal.h>
#include <compat/svr4/svr4_ioctl.h>
#include <compat/svr4/svr4_stropts.h>
#include <compat/svr4/svr4_socket.h>
static int svr4_soo_close(struct file *, struct thread *);
static int svr4_ptm_alloc(struct thread *);
static d_open_t streamsopen;
/*
* Device minor numbers
*/
enum {
dev_ptm = 10,
dev_arp = 26,
dev_icmp = 27,
dev_ip = 28,
dev_tcp = 35,
dev_udp = 36,
dev_rawip = 37,
dev_unix_dgram = 38,
dev_unix_stream = 39,
dev_unix_ord_stream = 40
};
static struct cdev *dt_ptm, *dt_arp, *dt_icmp, *dt_ip, *dt_tcp, *dt_udp,
*dt_rawip, *dt_unix_dgram, *dt_unix_stream, *dt_unix_ord_stream;
static struct fileops svr4_netops = {
.fo_read = soo_read,
.fo_write = soo_write,
.fo_ioctl = soo_ioctl,
.fo_poll = soo_poll,
.fo_kqfilter = soo_kqfilter,
.fo_stat = soo_stat,
.fo_close = svr4_soo_close
};
static struct cdevsw streams_cdevsw = {
.d_version = D_VERSION,
.d_open = streamsopen,
.d_name = "streams",
};
struct streams_softc {
struct isa_device *dev;
} ;
#define UNIT(dev) minor(dev) /* assume one minor number per unit */
typedef struct streams_softc *sc_p;
static int
streams_modevent(module_t mod, int type, void *unused)
{
switch (type) {
case MOD_LOAD:
dt_ptm = make_dev(&streams_cdevsw, dev_ptm, 0, 0, 0666,
"ptm");
dt_arp = make_dev(&streams_cdevsw, dev_arp, 0, 0, 0666,
"arp");
dt_icmp = make_dev(&streams_cdevsw, dev_icmp, 0, 0, 0666,
"icmp");
dt_ip = make_dev(&streams_cdevsw, dev_ip, 0, 0, 0666,
"ip");
dt_tcp = make_dev(&streams_cdevsw, dev_tcp, 0, 0, 0666,
"tcp");
dt_udp = make_dev(&streams_cdevsw, dev_udp, 0, 0, 0666,
"udp");
dt_rawip = make_dev(&streams_cdevsw, dev_rawip, 0, 0, 0666,
"rawip");
dt_unix_dgram = make_dev(&streams_cdevsw, dev_unix_dgram,
0, 0, 0666, "ticlts");
dt_unix_stream = make_dev(&streams_cdevsw, dev_unix_stream,
0, 0, 0666, "ticots");
dt_unix_ord_stream = make_dev(&streams_cdevsw,
dev_unix_ord_stream, 0, 0, 0666, "ticotsord");
if (! (dt_ptm && dt_arp && dt_icmp && dt_ip && dt_tcp &&
dt_udp && dt_rawip && dt_unix_dgram &&
dt_unix_stream && dt_unix_ord_stream)) {
printf("WARNING: device config for STREAMS failed\n");
printf("Suggest unloading streams KLD\n");
}
return 0;
case MOD_UNLOAD:
/* XXX should check to see if it's busy first */
destroy_dev(dt_ptm);
destroy_dev(dt_arp);
destroy_dev(dt_icmp);
destroy_dev(dt_ip);
destroy_dev(dt_tcp);
destroy_dev(dt_udp);
destroy_dev(dt_rawip);
destroy_dev(dt_unix_dgram);
destroy_dev(dt_unix_stream);
destroy_dev(dt_unix_ord_stream);
return 0;
default:
return EOPNOTSUPP;
break;
}
return 0;
}
static moduledata_t streams_mod = {
"streams",
streams_modevent,
0
};
DECLARE_MODULE(streams, streams_mod, SI_SUB_DRIVERS, SI_ORDER_ANY);
MODULE_VERSION(streams, 1);
/*
* We only need open() and close() routines. open() calls socreate()
* to allocate a "real" object behind the stream and mallocs some state
* info for use by the svr4 emulator; close() deallocates the state
* information and passes the underlying object to the normal socket close
* routine.
*/
static int
streamsopen(struct cdev *dev, int oflags, int devtype, struct thread *td)
{
struct filedesc *fdp;
struct svr4_strm *st;
struct socket *so;
struct file *fp;
int family, type, protocol;
int error, fd;
if (td->td_dupfd >= 0)
return ENODEV;
switch (minor(dev)) {
case dev_udp:
family = AF_INET;
type = SOCK_DGRAM;
protocol = IPPROTO_UDP;
break;
case dev_tcp:
family = AF_INET;
type = SOCK_STREAM;
protocol = IPPROTO_TCP;
break;
case dev_ip:
case dev_rawip:
family = AF_INET;
type = SOCK_RAW;
protocol = IPPROTO_IP;
break;
case dev_icmp:
family = AF_INET;
type = SOCK_RAW;
protocol = IPPROTO_ICMP;
break;
case dev_unix_dgram:
family = AF_LOCAL;
type = SOCK_DGRAM;
protocol = 0;
break;
case dev_unix_stream:
case dev_unix_ord_stream:
family = AF_LOCAL;
type = SOCK_STREAM;
protocol = 0;
break;
case dev_ptm:
return svr4_ptm_alloc(td);
default:
return EOPNOTSUPP;
}
fdp = td->td_proc->p_fd;
if ((error = falloc(td, &fp, &fd)) != 0)
return error;
/* An extra reference on `fp' has been held for us by falloc(). */
NET_LOCK_GIANT();
error = socreate(family, &so, type, protocol, td->td_ucred, td);
NET_UNLOCK_GIANT();
if (error) {
fdclose(fdp, fp, fd, td);
fdrop(fp, td);
return error;
}
FILE_LOCK(fp);
fp->f_data = so;
fp->f_flag = FREAD|FWRITE;
fp->f_ops = &svr4_netops;
fp->f_type = DTYPE_SOCKET;
FILE_UNLOCK(fp);
/*
* Allocate a stream structure and attach it to this socket.
* We don't bother locking so_emuldata for SVR4 stream sockets as
* its value is constant for the lifetime of the stream once it
* is initialized here.
*/
st = malloc(sizeof(struct svr4_strm), M_TEMP, M_WAITOK);
st->s_family = so->so_proto->pr_domain->dom_family;
st->s_cmd = ~0;
st->s_afd = -1;
st->s_eventmask = 0;
so->so_emuldata = st;
fdrop(fp, td);
td->td_dupfd = fd;
return ENXIO;
}
static int
svr4_ptm_alloc(td)
struct thread *td;
{
/*
* XXX this is very, very ugly. But I can't find a better
* way that won't duplicate a big amount of code from
* sys_open(). Ho hum...
*
* Fortunately for us, Solaris (at least 2.5.1) makes the
* /dev/ptmx open automatically just open a pty, that (after
* STREAMS I_PUSHes), is just a plain pty. fstat() is used
* to get the minor device number to map to a tty.
*
* Cycle through the names. If sys_open() returns ENOENT (or
* ENXIO), short circuit the cycle and exit.
*/
static char ptyname[] = "/dev/ptyXX";
static char ttyletters[] = "pqrstuwxyzPQRST";
static char ttynumbers[] = "0123456789abcdef";
struct proc *p;
register_t fd;
int error, l, n;
fd = -1;
n = 0;
l = 0;
p = td->td_proc;
while (fd == -1) {
ptyname[8] = ttyletters[l];
ptyname[9] = ttynumbers[n];
error = kern_open(td, ptyname, UIO_SYSSPACE, O_RDWR, 0);
switch (error) {
case ENOENT:
case ENXIO:
return error;
case 0:
td->td_dupfd = td->td_retval[0];
return ENXIO;
default:
if (ttynumbers[++n] == '\0') {
if (ttyletters[++l] == '\0')
break;
n = 0;
}
}
}
return ENOENT;
}
struct svr4_strm *
svr4_stream_get(fp)
struct file *fp;
{
struct socket *so;
if (fp == NULL || fp->f_type != DTYPE_SOCKET)
return NULL;
so = fp->f_data;
return so->so_emuldata;
}
static int
svr4_soo_close(struct file *fp, struct thread *td)
{
struct socket *so = fp->f_data;
/* CHECKUNIT_DIAG(ENXIO);*/
svr4_delete_socket(td->td_proc, fp);
free(so->so_emuldata, M_TEMP);
return soo_close(fp, td);
}