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Locking and cleanup of tty netgraph node. Tty stack is Giant-locked,

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so we need to acquire Giant in netgraph methods, so that we don't
race with line discipline methods. Remove NET_NEEDS_GIANT.

- Packets coming into node from netgraph are queued in ifqueue
  attached to node private data.
- Mutex in struct ifqueue is used to lock not only the queue, but
  the whole private data, and tp->t_lsc field.
- tp->t_lsc pointer is used to indicate whether line discipline is
  attached to netgraph or not.
- Use FLG_DIE flag to indicate that node may be destroyed.
  (This protection doesn't work, and it didn't before. Must be redesigned.)
- Increment ngt_unit atomically, removing mutex.
- Acquire Giant, when executing ngt_start() from netgraph context.
- Acquire Giant, when {,de}registering line discipline.
- Uncomment forcing queue mode on peers hook, since this is reasonable.
- Force queue mode on our hook, to avoid acquiring Giant when coming from
  network stack. We may already hold some mutexes at this point.

Cleanups:
- Use callout_pending() instead of our own flag.
- Remove spl(9) calls. Now we can use return() instead of ERROUT().

style(9):
- Sort includes.
- Sparse initializer for struct linesw.
- Remove some empty lines, sort declarations.

Reviewed by:	julian, phk
MFC after:	1 month
This commit is contained in:
Gleb Smirnoff 2005-01-13 07:43:12 +00:00
parent 9a03b27dba
commit d1426d7fc5
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=140164
1 changed files with 183 additions and 177 deletions
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360
sys/netgraph/ng_tty.c
View File

@ -1,4 +1,3 @@
/*
* ng_tty.c
*/
@ -56,29 +55,29 @@
* incoming characters to be buffered up until either the hotchar is
* seen or the mbuf is full (MHLEN bytes). Then all buffered characters
* are immediately delivered.
*
* NOTE: This node operates at spltty().
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/kernel.h>
#include <sys/conf.h>
#include <sys/mbuf.h>
#include <sys/malloc.h>
#include <sys/errno.h>
#include <sys/fcntl.h>
#include <sys/ioccom.h>
#include <sys/kernel.h>
#include <sys/malloc.h>
#include <sys/mbuf.h>
#include <sys/socket.h>
#include <sys/syslog.h>
#include <sys/tty.h>
#include <sys/ttycom.h>
#include <sys/syslog.h>
#include <sys/errno.h>
#include <sys/ioccom.h>
#include <net/if.h>
#include <net/if_var.h>
#include <netgraph/ng_message.h>
#include <netgraph/netgraph.h>
#include <netgraph/ng_tty.h>
NET_NEEDS_GIANT("ng_tty");
/* Misc defs */
#define MAX_MBUFQ 3 /* Max number of queued mbufs */
#define NGT_HIWATER 400 /* High water mark on output */
@ -88,9 +87,8 @@ struct ngt_sc {
struct tty *tp; /* Terminal device */
node_p node; /* Netgraph node */
hook_p hook; /* Netgraph hook */
struct ifqueue outq; /* Queue of outgoing data */
struct mbuf *m; /* Incoming data buffer */
struct mbuf *qhead, **qtail; /* Queue of outgoing mbuf's */
short qlen; /* Length of queue */
short hotchar; /* Hotchar, or -1 if none */
u_int flags; /* Flags */
struct callout chand; /* See man timeout(9) */
@ -98,25 +96,8 @@ struct ngt_sc {
typedef struct ngt_sc *sc_p;
/* Flags */
#define FLG_TIMEOUT 0x0001 /* A timeout is pending */
#define FLG_DEBUG 0x0002
/* Debugging */
#ifdef INVARIANTS
#define QUEUECHECK(sc) \
do { \
struct mbuf **mp; \
int k; \
\
for (k = 0, mp = &sc->qhead; \
k <= MAX_MBUFQ && *mp; \
k++, mp = &(*mp)->m_nextpkt); \
if (k != sc->qlen || k > MAX_MBUFQ || *mp || mp != sc->qtail) \
panic("%s: queue", __func__); \
} while (0)
#else
#define QUEUECHECK(sc) do {} while (0)
#endif
#define FLG_DIE 0x0004
/* Line discipline methods */
static int ngt_open(struct cdev *dev, struct tty *tp);
@ -136,7 +117,7 @@ static ng_newhook_t ngt_newhook;
static ng_connect_t ngt_connect;
static ng_rcvdata_t ngt_rcvdata;
static ng_disconnect_t ngt_disconnect;
static int ngt_mod_event(module_t mod, int event, void *data);
static int ngt_mod_event(module_t mod, int event, void *data);
/* Other stuff */
static void ngt_timeout(node_p node, hook_p hook, void *arg1, int arg2);
@ -145,14 +126,14 @@ static void ngt_timeout(node_p node, hook_p hook, void *arg1, int arg2);
/* Line discipline descriptor */
static struct linesw ngt_disc = {
ngt_open,
ngt_close,
ngt_read,
ngt_write,
ngt_tioctl,
ngt_input,
ngt_start,
ttymodem
.l_open = ngt_open,
.l_close = ngt_close,
.l_read = ngt_read,
.l_write = ngt_write,
.l_ioctl = ngt_tioctl,
.l_rint = ngt_input,
.l_start = ngt_start,
.l_modem = ttymodem,
};
/* Netgraph node type descriptor */
@ -171,16 +152,25 @@ static struct ng_type typestruct = {
NETGRAPH_INIT(tty, &typestruct);
/*
* XXXRW: ngt_unit is protected by ng_tty_mtx. ngt_ldisc is constant once
* ng_tty is initialized. ngt_nodeop_ok is untouched, and might want to be a
* sleep lock in the future?
* Locking:
*
* - node private data and tp->t_lsc is protected by mutex in struct
* ifqueue, locking is done using IF_XXX() macros.
* - in all tty methods we should acquire node ifqueue mutex, when accessing
* private data.
* - in _rcvdata() we should use locked versions of IF_{EN,DE}QUEUE() since
* we may have multiple _rcvdata() threads.
* - when calling any of tty methods from netgraph methods, we should
* acquire tty locking (now Giant).
*
* - ngt_unit is incremented atomically.
*/
static int ngt_unit;
static int ngt_nodeop_ok; /* OK to create/remove node */
static int ngt_ldisc;
static struct mtx ng_tty_mtx;
MTX_SYSINIT(ng_tty, &ng_tty_mtx, "ng_tty", MTX_DEF);
#define NGTLOCK(sc) IF_LOCK(&sc->outq)
#define NGTUNLOCK(sc) IF_UNLOCK(&sc->outq)
static int ngt_unit;
static int ngt_ldisc;
/******************************************************************
LINE DISCIPLINE METHODS
@ -188,7 +178,7 @@ MTX_SYSINIT(ng_tty, &ng_tty_mtx, "ng_tty", MTX_DEF);
/*
* Set our line discipline on the tty.
* Called from device open routine or ttioctl() at >= splsofttty()
* Called from device open routine or ttioctl()
*/
static int
ngt_open(struct cdev *dev, struct tty *tp)
@ -196,53 +186,50 @@ ngt_open(struct cdev *dev, struct tty *tp)
struct thread *const td = curthread; /* XXX */
char name[sizeof(NG_TTY_NODE_TYPE) + 8];
sc_p sc;
int s, error;
int error;
/* Super-user only */
if ((error = suser(td)))
return (error);
s = splnet();
(void) spltty(); /* XXX is this necessary? */
tp->t_hotchar = NG_TTY_DFL_HOTCHAR;
/* Initialize private struct */
MALLOC(sc, sc_p, sizeof(*sc), M_NETGRAPH, M_WAITOK | M_ZERO);
if (sc == NULL) {
error = ENOMEM;
goto done;
}
if (sc == NULL)
return (ENOMEM);
sc->tp = tp;
sc->hotchar = NG_TTY_DFL_HOTCHAR;
sc->qtail = &sc->qhead;
QUEUECHECK(sc);
ng_callout_init(&sc->chand);
sc->hotchar = tp->t_hotchar = NG_TTY_DFL_HOTCHAR;
mtx_init(&sc->outq.ifq_mtx, "ng_tty node+queue", NULL, MTX_DEF);
IFQ_SET_MAXLEN(&sc->outq, MAX_MBUFQ);
NGTLOCK(sc);
/* Setup netgraph node */
ngt_nodeop_ok = 1;
error = ng_make_node_common(&typestruct, &sc->node);
ngt_nodeop_ok = 0;
if (error) {
NGTUNLOCK(sc);
FREE(sc, M_NETGRAPH);
goto done;
return (error);
}
mtx_lock(&ng_tty_mtx);
snprintf(name, sizeof(name), "%s%d", typestruct.name, ngt_unit++);
mtx_unlock(&ng_tty_mtx);
atomic_add_int(&ngt_unit, 1);
snprintf(name, sizeof(name), "%s%d", typestruct.name, ngt_unit);
/* Assign node its name */
if ((error = ng_name_node(sc->node, name))) {
log(LOG_ERR, "%s: node name exists?\n", name);
ngt_nodeop_ok = 1;
sc->flags |= FLG_DIE;
NGTUNLOCK(sc);
NG_NODE_UNREF(sc->node);
ngt_nodeop_ok = 0;
goto done;
log(LOG_ERR, "%s: node name exists?\n", name);
return (error);
}
/* Set back pointers */
NG_NODE_SET_PRIVATE(sc->node, sc);
tp->t_lsc = sc;
ng_callout_init(&sc->chand);
/*
* Pre-allocate cblocks to the an appropriate amount.
* I'm not sure what is appropriate.
@ -253,37 +240,31 @@ ngt_open(struct cdev *dev, struct tty *tp)
clist_alloc_cblocks(&tp->t_outq,
MLEN + NGT_HIWATER, MLEN + NGT_HIWATER);
done:
/* Done */
splx(s);
return (error);
NGTUNLOCK(sc);
return (0);
}
/*
* Line specific close routine, called from device close routine
* and from ttioctl at >= splsofttty(). This causes the node to
* be destroyed as well.
* and from ttioctl. This causes the node to be destroyed as well.
*/
static int
ngt_close(struct tty *tp, int flag)
{
const sc_p sc = (sc_p) tp->t_lsc;
int s;
s = spltty();
ttyflush(tp, FREAD | FWRITE);
clist_free_cblocks(&tp->t_outq);
if (sc != NULL) {
if (sc->flags & FLG_TIMEOUT) {
NGTLOCK(sc);
if (callout_pending(&sc->chand))
ng_uncallout(&sc->chand, sc->node);
sc->flags &= ~FLG_TIMEOUT;
}
ngt_nodeop_ok = 1;
ng_rmnode_self(sc->node);
ngt_nodeop_ok = 0;
tp->t_lsc = NULL;
sc->flags |= FLG_DIE;
NGTUNLOCK(sc);
ng_rmnode_self(sc->node);
}
splx(s);
return (0);
}
@ -312,9 +293,11 @@ static int
ngt_tioctl(struct tty *tp, u_long cmd, caddr_t data, int flag, struct thread *td)
{
const sc_p sc = (sc_p) tp->t_lsc;
int s, error = 0;
s = spltty();
if (sc == NULL)
/* No node attached */
return (0);
switch (cmd) {
case NGIOCGINFO:
{
@ -322,25 +305,28 @@ ngt_tioctl(struct tty *tp, u_long cmd, caddr_t data, int flag, struct thread *td
const node_p node = sc->node;
bzero(ni, sizeof(*ni));
NGTLOCK(sc);
if (NG_NODE_HAS_NAME(node))
strncpy(ni->name, NG_NODE_NAME(node), sizeof(ni->name) - 1);
strncpy(ni->type, node->nd_type->name, sizeof(ni->type) - 1);
ni->id = (u_int32_t) ng_node2ID(node);
ni->hooks = NG_NODE_NUMHOOKS(node);
NGTUNLOCK(sc);
break;
}
default:
ERROUT(ENOIOCTL);
return (ENOIOCTL);
}
done:
splx(s);
return (error);
return (0);
}
/*
* Receive data coming from the device. We get one character at
* a time, which is kindof silly.
* Only guaranteed to be at splsofttty() or spltty().
*
* Full locking of softc is not required, since we are the only
* user of sc->m.
*/
static int
ngt_input(int c, struct tty *tp)
@ -348,26 +334,27 @@ ngt_input(int c, struct tty *tp)
const sc_p sc = (sc_p) tp->t_lsc;
const node_p node = sc->node;
struct mbuf *m;
int s, error = 0;
int error = 0;
if (!sc || tp != sc->tp)
if (sc == NULL)
/* No node attached */
return (0);
s = spltty();
if (!sc->hook)
ERROUT(0);
if (tp != sc->tp)
panic("ngt_input");
/* Check for error conditions */
if ((tp->t_state & TS_CONNECTED) == 0) {
if (sc->flags & FLG_DEBUG)
log(LOG_DEBUG, "%s: no carrier\n", NG_NODE_NAME(node));
ERROUT(0);
return (0);
}
if (c & TTY_ERRORMASK) {
/* framing error or overrun on this char */
if (sc->flags & FLG_DEBUG)
log(LOG_DEBUG, "%s: line error %x\n",
NG_NODE_NAME(node), c & TTY_ERRORMASK);
ERROUT(0);
return (0);
}
c &= TTY_CHARMASK;
@ -378,7 +365,7 @@ ngt_input(int c, struct tty *tp)
if (sc->flags & FLG_DEBUG)
log(LOG_ERR,
"%s: can't get mbuf\n", NG_NODE_NAME(node));
ERROUT(ENOBUFS);
return (ENOBUFS);
}
m->m_len = m->m_pkthdr.len = 0;
m->m_pkthdr.rcvif = NULL;
@ -394,39 +381,47 @@ ngt_input(int c, struct tty *tp)
/* Ship off mbuf if it's time */
if (sc->hotchar == -1 || c == sc->hotchar || m->m_len >= MHLEN) {
m->m_data = m->m_pktdat;
NG_SEND_DATA_ONLY(error, sc->hook, m);
sc->m = NULL;
/*
* We have built our mbuf without checking that we actually
* have a hook to send it. This was done to avoid
* acquiring mutex on each character. Check now.
*
*/
NGTLOCK(sc);
if (sc->hook == NULL) {
NGTUNLOCK(sc);
m_freem(m);
return (0); /* XXX: original behavior */
}
NG_SEND_DATA_ONLY(error, sc->hook, m); /* Will queue */
NGTUNLOCK(sc);
}
done:
splx(s);
return (error);
}
/*
* This is called when the device driver is ready for more output.
* Called from tty system at splsofttty() or spltty().
* Also call from ngt_rcv_data() when a new mbuf is available for output.
* Also called from ngt_rcv_data() when a new mbuf is available for output.
*/
static int
ngt_start(struct tty *tp)
{
const sc_p sc = (sc_p) tp->t_lsc;
int s;
s = spltty();
while (tp->t_outq.c_cc < NGT_HIWATER) { /* XXX 2.2 specific ? */
struct mbuf *m = sc->qhead;
struct mbuf *m;
/* Remove first mbuf from queue */
if (!m)
IF_DEQUEUE(&sc->outq, m);
if (m == NULL)
break;
if ((sc->qhead = m->m_nextpkt) == NULL)
sc->qtail = &sc->qhead;
sc->qlen--;
QUEUECHECK(sc);
/* Send as much of it as possible */
while (m) {
while (m != NULL) {
int sent;
sent = m->m_len
@ -439,13 +434,8 @@ ngt_start(struct tty *tp)
}
/* Put remainder of mbuf chain (if any) back on queue */
if (m) {
m->m_nextpkt = sc->qhead;
sc->qhead = m;
if (sc->qtail == &sc->qhead)
sc->qtail = &m->m_nextpkt;
sc->qlen++;
QUEUECHECK(sc);
if (m != NULL) {
IF_PREPEND(&sc->outq, m);
break;
}
}
@ -457,11 +447,10 @@ ngt_start(struct tty *tp)
/* This timeout is needed for operation on a pseudo-tty, because the
* pty code doesn't call pppstart after it has drained the t_outq. */
if (sc->qhead && (sc->flags & FLG_TIMEOUT) == 0) {
/* XXX: outq not locked */
if (!IFQ_IS_EMPTY(&sc->outq) && !callout_pending(&sc->chand))
ng_callout(&sc->chand, sc->node, NULL, 1, ngt_timeout, NULL, 0);
sc->flags |= FLG_TIMEOUT;
}
splx(s);
return (0);
}
@ -472,12 +461,10 @@ static void
ngt_timeout(node_p node, hook_p hook, void *arg1, int arg2)
{
const sc_p sc = NG_NODE_PRIVATE(node);
int s;
s = spltty();
sc->flags &= ~FLG_TIMEOUT;
mtx_lock(&Giant);
ngt_start(sc->tp);
splx(s);
mtx_unlock(&Giant);
}
/******************************************************************
@ -503,28 +490,35 @@ static int
ngt_newhook(node_p node, hook_p hook, const char *name)
{
const sc_p sc = NG_NODE_PRIVATE(node);
int s, error = 0;
if (strcmp(name, NG_TTY_HOOK))
return (EINVAL);
s = spltty();
if (sc->hook)
ERROUT(EISCONN);
return (EISCONN);
NGTLOCK(sc);
sc->hook = hook;
done:
splx(s);
return (error);
NGTUNLOCK(sc);
return (0);
}
/*
* Set the hooks into queueing mode (for outgoing packets)
* Force single client at a time.
* Set the hook into queueing mode (for outgoing packets),
* so that we wont deliver mbuf thru the whole graph holding
* tty locks.
*/
static int
ngt_connect(hook_p hook)
{
/*NG_HOOK_FORCE_WRITER(hook);
NG_HOOK_FORCE_QUEUE(NG_HOOK_PEER(hook));*/
NG_HOOK_FORCE_QUEUE(NG_HOOK_PEER(hook));
/*
* XXX: While ngt_start() is Giant-locked, queue incoming
* packets, too. Otherwise we acquire Giant holding some
* IP stack locks, e.g. divinp, and this makes WITNESS scream.
*/
NG_HOOK_FORCE_QUEUE(hook);
return (0);
}
@ -535,35 +529,43 @@ static int
ngt_disconnect(hook_p hook)
{
const sc_p sc = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));
int s;
s = spltty();
if (hook != sc->hook)
panic(__func__);
NGTLOCK(sc);
sc->hook = NULL;
m_freem(sc->m);
sc->m = NULL;
splx(s);
NGTUNLOCK(sc);
return (0);
}
/*
* Remove this node. The does the netgraph portion of the shutdown.
* This should only be called indirectly from ngt_close().
*
* tp->t_lsc is already NULL, so we should be protected from
* tty calls now.
*/
static int
ngt_shutdown(node_p node)
{
const sc_p sc = NG_NODE_PRIVATE(node);
if (!ngt_nodeop_ok)
NGTLOCK(sc);
if (!(sc->flags & FLG_DIE)) {
NGTUNLOCK(sc);
return (EOPNOTSUPP);
NG_NODE_SET_PRIVATE(node, NULL);
NG_NODE_UNREF(sc->node);
m_freem(sc->qhead);
}
NGTUNLOCK(sc);
/* Free resources */
_IF_DRAIN(&sc->outq);
mtx_destroy(&(sc)->outq.ifq_mtx);
m_freem(sc->m);
bzero(sc, sizeof(*sc));
NG_NODE_UNREF(sc->node);
FREE(sc, M_NETGRAPH);
return (0);
}
@ -575,30 +577,37 @@ static int
ngt_rcvdata(hook_p hook, item_p item)
{
const sc_p sc = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));
int s, error = 0;
struct mbuf *m;
int qlen;
if (hook != sc->hook)
panic(__func__);
NGI_GET_M(item, m);
NG_FREE_ITEM(item);
s = spltty();
if (sc->qlen >= MAX_MBUFQ)
ERROUT(ENOBUFS);
m->m_nextpkt = NULL;
*sc->qtail = m;
sc->qtail = &m->m_nextpkt;
sc->qlen++;
QUEUECHECK(sc);
m = NULL;
if (sc->qlen == 1)
IF_LOCK(&sc->outq);
if (_IF_QFULL(&sc->outq)) {
_IF_DROP(&sc->outq);
IF_UNLOCK(&sc->outq);
NG_FREE_M(m);
return (ENOBUFS);
}
_IF_ENQUEUE(&sc->outq, m);
qlen = sc->outq.ifq_len;
IF_UNLOCK(&sc->outq);
/*
* If qlen > 1, then we should already have a scheduled callout.
*/
if (qlen == 1) {
mtx_lock(&Giant);
ngt_start(sc->tp);
done:
splx(s);
if (m)
m_freem(m);
return (error);
mtx_unlock(&Giant);
}
return (0);
}
/*
@ -608,9 +617,8 @@ static int
ngt_rcvmsg(node_p node, item_p item, hook_p lasthook)
{
const sc_p sc = NG_NODE_PRIVATE(node);
struct ng_mesg *resp = NULL;
struct ng_mesg *msg, *resp = NULL;
int error = 0;
struct ng_mesg *msg;
NGI_GET_MSG(item, msg);
switch (msg->header.typecookie) {
@ -658,29 +666,28 @@ ngt_rcvmsg(node_p node, item_p item, hook_p lasthook)
static int
ngt_mod_event(module_t mod, int event, void *data)
{
/* struct ng_type *const type = data;*/
int s, error = 0;
int error = 0;
switch (event) {
case MOD_LOAD:
/* Register line discipline */
s = spltty();
mtx_lock(&Giant);
if ((ngt_ldisc = ldisc_register(NETGRAPHDISC, &ngt_disc)) < 0) {
splx(s);
mtx_unlock(&Giant);
log(LOG_ERR, "%s: can't register line discipline",
__func__);
return (EIO);
}
splx(s);
mtx_unlock(&Giant);
break;
case MOD_UNLOAD:
/* Unregister line discipline */
s = spltty();
mtx_lock(&Giant);
ldisc_deregister(ngt_ldisc);
splx(s);
mtx_unlock(&Giant);
break;
default:
@ -689,4 +696,3 @@ ngt_mod_event(module_t mod, int event, void *data)
}
return (error);
}