#include <sys/param.h>
#include <sys/proc.h>
#include <sys/lock.h>
#include <kern/cpu_number.h>
#include <kern/thread.h>
#include <mach/mach_types.h>
#if 0
#define COUNT(p, x) if (p) (p)->p_locks += (x)
#else
#define COUNT(p, x)
#endif
#if NCPUS > 1
int lock_wait_time = 100;
#define PAUSE(lkp, wanted) \
if (lock_wait_time > 0) { \
int i; \
\
simple_unlock(&lkp->lk_interlock); \
for (i = lock_wait_time; i > 0; i--) \
if (!(wanted)) \
break; \
simple_lock(&lkp->lk_interlock); \
} \
if (!(wanted)) \
break;
#else
#define PAUSE(lkp, wanted)
#endif
#define ACQUIRE(lkp, error, extflags, wanted) \
PAUSE(lkp, wanted); \
for (error = 0; wanted; ) { \
(lkp)->lk_waitcount++; \
simple_unlock(&(lkp)->lk_interlock); \
error = tsleep((void *)lkp, (lkp)->lk_prio, \
(lkp)->lk_wmesg, (lkp)->lk_timo); \
simple_lock(&(lkp)->lk_interlock); \
(lkp)->lk_waitcount--; \
if (error) \
break; \
if ((extflags) & LK_SLEEPFAIL) { \
error = ENOLCK; \
break; \
} \
}
void
lockinit(lkp, prio, wmesg, timo, flags)
struct lock__bsd__ *lkp;
int prio;
char *wmesg;
int timo;
int flags;
{
bzero(lkp, sizeof(struct lock__bsd__));
simple_lock_init(&lkp->lk_interlock);
lkp->lk_flags = flags & LK_EXTFLG_MASK;
lkp->lk_prio = prio;
lkp->lk_timo = timo;
lkp->lk_wmesg = wmesg;
lkp->lk_lockholder = LK_NOPROC;
lkp->lk_lockthread = 0;
}
int
lockstatus(lkp)
struct lock__bsd__ *lkp;
{
int lock_type = 0;
simple_lock(&lkp->lk_interlock);
if (lkp->lk_exclusivecount != 0)
lock_type = LK_EXCLUSIVE;
else if (lkp->lk_sharecount != 0)
lock_type = LK_SHARED;
simple_unlock(&lkp->lk_interlock);
return (lock_type);
}
int
lockmgr(lkp, flags, interlkp, p)
struct lock__bsd__ *lkp;
u_int flags;
simple_lock_t interlkp;
struct proc *p;
{
int error;
pid_t pid;
int extflags;
void *self;
error = 0; self = current_thread();
if (p)
pid = p->p_pid;
else
pid = LK_KERNPROC;
simple_lock(&lkp->lk_interlock);
if (flags & LK_INTERLOCK)
simple_unlock(interlkp);
extflags = (flags | lkp->lk_flags) & LK_EXTFLG_MASK;
#if 0
if (lkp->lk_flags & (LK_DRAINING|LK_DRAINED)) {
if (lkp->lk_flags & LK_DRAINED)
panic("lockmgr: using decommissioned lock");
if ((flags & LK_TYPE_MASK) != LK_RELEASE ||
(lkp->lk_lockholder != pid && lkp->lk_lockthread != self)
panic("lockmgr: non-release on draining lock: %d\n",
flags & LK_TYPE_MASK);
lkp->lk_flags &= ~LK_DRAINING;
if ((flags & LK_REENABLE) == 0)
lkp->lk_flags |= LK_DRAINED;
}
#endif
switch (flags & LK_TYPE_MASK) {
case LK_SHARED:
if (lkp->lk_lockholder != pid || lkp->lk_lockthread != self) {
if ((extflags & LK_NOWAIT) && (lkp->lk_flags &
(LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE))) {
error = EBUSY;
break;
}
ACQUIRE(lkp, error, extflags, lkp->lk_flags &
(LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE));
if (error)
break;
lkp->lk_sharecount++;
COUNT(p, 1);
break;
}
lkp->lk_sharecount++;
COUNT(p, 1);
case LK_DOWNGRADE:
if (lkp->lk_lockholder != pid ||
lkp->lk_lockthread != self ||
lkp->lk_exclusivecount == 0)
panic("lockmgr: not holding exclusive lock");
lkp->lk_sharecount += lkp->lk_exclusivecount;
lkp->lk_exclusivecount = 0;
lkp->lk_flags &= ~LK_HAVE_EXCL;
lkp->lk_lockholder = LK_NOPROC;
lkp->lk_lockthread = 0;
if (lkp->lk_waitcount)
wakeup((void *)lkp);
break;
case LK_EXCLUPGRADE:
if (lkp->lk_flags & LK_WANT_UPGRADE) {
lkp->lk_sharecount--;
COUNT(p, -1);
error = EBUSY;
break;
}
case LK_UPGRADE:
if ((lkp->lk_lockholder == pid &&
lkp->lk_lockthread == self) ||
lkp->lk_sharecount <= 0)
panic("lockmgr: upgrade exclusive lock");
lkp->lk_sharecount--;
COUNT(p, -1);
if ((extflags & LK_NOWAIT) &&
((lkp->lk_flags & LK_WANT_UPGRADE) ||
lkp->lk_sharecount > 1)) {
error = EBUSY;
break;
}
if ((lkp->lk_flags & LK_WANT_UPGRADE) == 0) {
lkp->lk_flags |= LK_WANT_UPGRADE;
ACQUIRE(lkp, error, extflags, lkp->lk_sharecount);
lkp->lk_flags &= ~LK_WANT_UPGRADE;
if (error)
break;
lkp->lk_flags |= LK_HAVE_EXCL;
lkp->lk_lockholder = pid;
lkp->lk_lockthread = self;
if (lkp->lk_exclusivecount != 0)
panic("lockmgr: non-zero exclusive count");
lkp->lk_exclusivecount = 1;
COUNT(p, 1);
break;
}
if (lkp->lk_sharecount == 0 && lkp->lk_waitcount)
wakeup((void *)lkp);
case LK_EXCLUSIVE:
if (lkp->lk_lockholder == pid && lkp->lk_lockthread == self) {
if ((extflags & LK_CANRECURSE) == 0)
panic("lockmgr: locking against myself");
lkp->lk_exclusivecount++;
COUNT(p, 1);
break;
}
if ((extflags & LK_NOWAIT) && ((lkp->lk_flags &
(LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE)) ||
lkp->lk_sharecount != 0)) {
error = EBUSY;
break;
}
ACQUIRE(lkp, error, extflags, lkp->lk_flags &
(LK_HAVE_EXCL | LK_WANT_EXCL));
if (error)
break;
lkp->lk_flags |= LK_WANT_EXCL;
ACQUIRE(lkp, error, extflags, lkp->lk_sharecount != 0 ||
(lkp->lk_flags & LK_WANT_UPGRADE));
lkp->lk_flags &= ~LK_WANT_EXCL;
if (error)
break;
lkp->lk_flags |= LK_HAVE_EXCL;
lkp->lk_lockholder = pid;
lkp->lk_lockthread = self;
if (lkp->lk_exclusivecount != 0)
panic("lockmgr: non-zero exclusive count");
lkp->lk_exclusivecount = 1;
COUNT(p, 1);
break;
case LK_RELEASE:
if (lkp->lk_exclusivecount != 0) {
if (pid != lkp->lk_lockholder ||
lkp->lk_lockthread != self)
panic("lockmgr: pid %d, thread 0x%8x,"
" not exclusive lock holder pid %d"
" thread 0x%8x unlocking, exclusive count %d",
pid, self, lkp->lk_lockholder,
lkp->lk_lockthread, lkp->lk_exclusivecount);
lkp->lk_exclusivecount--;
COUNT(p, -1);
if (lkp->lk_exclusivecount == 0) {
lkp->lk_flags &= ~LK_HAVE_EXCL;
lkp->lk_lockholder = LK_NOPROC;
lkp->lk_lockthread = 0;
}
} else if (lkp->lk_sharecount != 0) {
lkp->lk_sharecount--;
COUNT(p, -1);
}
if (lkp->lk_waitcount)
wakeup((void *)lkp);
break;
case LK_DRAIN:
if (lkp->lk_lockholder == pid && lkp->lk_lockthread == self)
panic("lockmgr: draining against myself");
if ((extflags & LK_NOWAIT) && ((lkp->lk_flags &
(LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE)) ||
lkp->lk_sharecount != 0 || lkp->lk_waitcount != 0)) {
error = EBUSY;
break;
}
PAUSE(lkp, ((lkp->lk_flags &
(LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE)) ||
lkp->lk_sharecount != 0 || lkp->lk_waitcount != 0));
for (error = 0; ((lkp->lk_flags &
(LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE)) ||
lkp->lk_sharecount != 0 || lkp->lk_waitcount != 0); ) {
lkp->lk_flags |= LK_WAITDRAIN;
simple_unlock(&lkp->lk_interlock);
if (error = tsleep((void *)&lkp->lk_flags, lkp->lk_prio,
lkp->lk_wmesg, lkp->lk_timo))
return (error);
if ((extflags) & LK_SLEEPFAIL)
return (ENOLCK);
simple_lock(&lkp->lk_interlock);
}
lkp->lk_flags |= LK_DRAINING | LK_HAVE_EXCL;
lkp->lk_lockholder = pid;
lkp->lk_lockthread = self;
lkp->lk_exclusivecount = 1;
COUNT(p, 1);
break;
default:
simple_unlock(&lkp->lk_interlock);
panic("lockmgr: unknown locktype request %d",
flags & LK_TYPE_MASK);
}
if ((lkp->lk_flags & LK_WAITDRAIN) && ((lkp->lk_flags &
(LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE)) == 0 &&
lkp->lk_sharecount == 0 && lkp->lk_waitcount == 0)) {
lkp->lk_flags &= ~LK_WAITDRAIN;
wakeup((void *)&lkp->lk_flags);
}
simple_unlock(&lkp->lk_interlock);
return (error);
}
lockmgr_printinfo(lkp)
struct lock__bsd__ *lkp;
{
if (lkp->lk_sharecount)
printf(" lock type %s: SHARED (count %d)", lkp->lk_wmesg,
lkp->lk_sharecount);
else if (lkp->lk_flags & LK_HAVE_EXCL)
printf(" lock type %s: EXCL (count %d) by pid %d",
lkp->lk_wmesg, lkp->lk_exclusivecount, lkp->lk_lockholder);
if (lkp->lk_waitcount > 0)
printf(" with %d pending", lkp->lk_waitcount);
}