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Make nmdm(4) destroy devices when both sides of a pair are disconnected.

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This makes it possible to kldunload nmdm.ko when there are no users of it.

Reviewed by:	kib
Sponsored by:	Nginx, Inc.
This commit is contained in:
Gleb Smirnoff 2013-12-18 12:53:48 +00:00
parent e1e585a87c
commit a95ecdf0cf
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=259550
1 changed files with 104 additions and 32 deletions
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136
sys/dev/nmdm/nmdm.c
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@ -58,6 +58,8 @@ static tsw_inwakeup_t nmdm_outwakeup;
static tsw_outwakeup_t nmdm_inwakeup;
static tsw_param_t nmdm_param;
static tsw_modem_t nmdm_modem;
static tsw_close_t nmdm_close;
static tsw_free_t nmdm_free;
static struct ttydevsw nmdm_class = {
.tsw_flags = TF_NOPREFIX,
@ -65,6 +67,8 @@ static struct ttydevsw nmdm_class = {
.tsw_outwakeup = nmdm_outwakeup,
.tsw_param = nmdm_param,
.tsw_modem = nmdm_modem,
.tsw_close = nmdm_close,
.tsw_free = nmdm_free,
};
static void nmdm_task_tty(void *, int);
@ -94,15 +98,83 @@ struct nmdmsoftc {
static int nmdm_count = 0;
static struct nmdmsoftc *
nmdm_alloc(unsigned long unit)
static void
nmdm_close(struct tty *tp)
{
struct nmdmpart *np;
struct nmdmpart *onp;
struct tty *otp;
np = tty_softc(tp);
onp = np->np_other;
otp = onp->np_tty;
/* If second part is opened, do not destroy ourselves. */
if (tty_opened(otp))
return;
/* Shut down self. */
tty_rel_gone(tp);
/* Shut down second part. */
tty_lock(tp);
onp = np->np_other;
if (onp == NULL)
return;
otp = onp->np_tty;
tty_rel_gone(otp);
tty_lock(tp);
}
static void
nmdm_free(void *softc)
{
struct nmdmpart *np = (struct nmdmpart *)softc;
struct nmdmsoftc *ns = np->np_pair;
callout_drain(&np->np_callout);
taskqueue_drain(taskqueue_swi, &np->np_task);
/*
* The function is called on both parts simultaneously. We serialize
* with help of ns_mtx. The first invocation should return and
* delegate freeing of resources to the second.
*/
mtx_lock(&ns->ns_mtx);
if (np->np_other != NULL) {
np->np_other->np_other = NULL;
mtx_unlock(&ns->ns_mtx);
return;
}
mtx_destroy(&ns->ns_mtx);
free(ns, M_NMDM);
atomic_subtract_int(&nmdm_count, 1);
}
static void
nmdm_clone(void *arg, struct ucred *cred, char *name, int nameen,
struct cdev **dev)
{
struct nmdmsoftc *ns;
struct tty *tp;
unsigned long unit;
char *end;
int error;
atomic_add_int(&nmdm_count, 1);
if (*dev != NULL)
return;
if (strncmp(name, "nmdm", 4) != 0)
return;
ns = malloc(sizeof(*ns), M_NMDM, M_WAITOK|M_ZERO);
/* Device name must be "nmdm%lu%c", where %c is 'A' or 'B'. */
name += 4;
unit = strtoul(name, &end, 10);
if (unit == ULONG_MAX || name == end)
return;
if ((end[0] != 'A' && end[0] != 'B') || end[1] != '\0')
return;
ns = malloc(sizeof(*ns), M_NMDM, M_WAITOK | M_ZERO);
mtx_init(&ns->ns_mtx, "nmdm", NULL, MTX_DEF);
/* Hook the pairs together. */
@ -119,43 +191,33 @@ nmdm_alloc(unsigned long unit)
/* Create device nodes. */
tp = ns->ns_part1.np_tty = tty_alloc_mutex(&nmdm_class, &ns->ns_part1,
&ns->ns_mtx);
tty_makedev(tp, NULL, "nmdm%luA", unit);
error = tty_makedevf(tp, NULL, end[0] == 'A' ? TTYMK_CLONING : 0,
"nmdm%luA", unit);
if (error) {
mtx_destroy(&ns->ns_mtx);
free(ns, M_NMDM);
return;
}
tp = ns->ns_part2.np_tty = tty_alloc_mutex(&nmdm_class, &ns->ns_part2,
&ns->ns_mtx);
tty_makedev(tp, NULL, "nmdm%luB", unit);
return (ns);
}
static void
nmdm_clone(void *arg, struct ucred *cred, char *name, int nameen,
struct cdev **dev)
{
unsigned long unit;
char *end;
struct nmdmsoftc *ns;
if (*dev != NULL)
error = tty_makedevf(tp, NULL, end[0] == 'B' ? TTYMK_CLONING : 0,
"nmdm%luB", unit);
if (error) {
mtx_lock(&ns->ns_mtx);
/* see nmdm_free() */
ns->ns_part1.np_other = NULL;
atomic_add_int(&nmdm_count, 1);
tty_rel_gone(ns->ns_part1.np_tty);
return;
if (strncmp(name, "nmdm", 4) != 0)
return;
/* Device name must be "nmdm%lu%c", where %c is 'A' or 'B'. */
name += 4;
unit = strtoul(name, &end, 10);
if (unit == ULONG_MAX || name == end)
return;
if ((end[0] != 'A' && end[0] != 'B') || end[1] != '\0')
return;
/* XXX: pass privileges? */
ns = nmdm_alloc(unit);
}
if (end[0] == 'A')
*dev = ns->ns_part1.np_tty->t_dev;
else
*dev = ns->ns_part2.np_tty->t_dev;
atomic_add_int(&nmdm_count, 1);
}
static void
@ -187,6 +249,10 @@ nmdm_task_tty(void *arg, int pending __unused)
tp = np->np_tty;
tty_lock(tp);
if (tty_gone(tp)) {
tty_unlock(tp);
return;
}
otp = np->np_other->np_tty;
KASSERT(otp != NULL, ("NULL otp in nmdmstart"));
@ -203,6 +269,12 @@ nmdm_task_tty(void *arg, int pending __unused)
}
}
/* This may happen when we are in detach process. */
if (tty_gone(otp)) {
tty_unlock(otp);
return;
}
while (ttydisc_rint_poll(otp) > 0) {
if (np->np_rate && !np->np_quota)
break;