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Some kern_lock code improvements. Add missing wakeup, and enable

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disabling some diagnostics when memory or speed is at a premium.
This commit is contained in:
John Dyson 1998-03-07 19:25:34 +00:00
parent 3124c3e093
commit 9b2e5bad34
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=34194
1 changed files with 43 additions and 10 deletions
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53
sys/kern/kern_lock.c
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@ -38,7 +38,7 @@
* SUCH DAMAGE.
*
* @(#)kern_lock.c 8.18 (Berkeley) 5/21/95
* $Id: kern_lock.c,v 1.16 1998/02/06 12:13:23 eivind Exp $
* $Id: kern_lock.c,v 1.17 1998/02/11 00:05:26 eivind Exp $
*/
#include "opt_lint.h"
@ -92,9 +92,15 @@ shareunlock(struct lock *lkp, int decr) {
#endif
#endif
lkp->lk_sharecount -= decr;
if (lkp->lk_sharecount == 0)
if (lkp->lk_sharecount == decr) {
lkp->lk_flags &= ~LK_SHARE_NONZERO;
if (lkp->lk_flags & (LK_WANT_UPGRADE | LK_WANT_EXCL)) {
wakeup(lkp);
}
lkp->lk_sharecount = 0;
} else {
lkp->lk_sharecount -= decr;
}
}
/*
@ -125,7 +131,7 @@ apause(struct lock *lkp, int flags) {
static int
acquire(struct lock *lkp, int extflags, int wanted) {
int error;
int s, error;
if ((extflags & LK_NOWAIT) && (lkp->lk_flags & wanted)) {
return EBUSY;
@ -137,21 +143,29 @@ acquire(struct lock *lkp, int extflags, int wanted) {
return 0;
}
s = splhigh();
while ((lkp->lk_flags & wanted) != 0) {
lkp->lk_flags |= LK_WAIT_NONZERO;
lkp->lk_waitcount++;
simple_unlock(&lkp->lk_interlock);
error = tsleep(lkp, lkp->lk_prio, lkp->lk_wmesg, lkp->lk_timo);
simple_lock(&lkp->lk_interlock);
lkp->lk_waitcount--;
if (lkp->lk_waitcount == 0)
if (lkp->lk_waitcount == 1) {
lkp->lk_flags &= ~LK_WAIT_NONZERO;
if (error)
lkp->lk_waitcount = 0;
} else {
lkp->lk_waitcount--;
}
if (error) {
splx(s);
return error;
}
if (extflags & LK_SLEEPFAIL) {
splx(s);
return ENOLCK;
}
}
splx(s);
return 0;
}
@ -206,8 +220,10 @@ lockmgr(lkp, flags, interlkp, p)
/* fall into downgrade */
case LK_DOWNGRADE:
#if !defined(MAX_PERF)
if (lkp->lk_lockholder != pid || lkp->lk_exclusivecount == 0)
panic("lockmgr: not holding exclusive lock");
#endif
sharelock(lkp, lkp->lk_exclusivecount);
lkp->lk_exclusivecount = 0;
lkp->lk_flags &= ~LK_HAVE_EXCL;
@ -239,8 +255,10 @@ lockmgr(lkp, flags, interlkp, p)
* after the upgrade). If we return an error, the file
* will always be unlocked.
*/
#if !defined(MAX_PERF)
if ((lkp->lk_lockholder == pid) || (lkp->lk_sharecount <= 0))
panic("lockmgr: upgrade exclusive lock");
#endif
shareunlock(lkp, 1);
COUNT(p, -1);
/*
@ -259,14 +277,17 @@ lockmgr(lkp, flags, interlkp, p)
* drop to zero, then take exclusive lock.
*/
lkp->lk_flags |= LK_WANT_UPGRADE;
error = acquire(lkp, extflags , LK_SHARE_NONZERO);
error = acquire(lkp, extflags, LK_SHARE_NONZERO);
lkp->lk_flags &= ~LK_WANT_UPGRADE;
if (error)
break;
lkp->lk_flags |= LK_HAVE_EXCL;
lkp->lk_lockholder = pid;
#if !defined(MAX_PERF)
if (lkp->lk_exclusivecount != 0)
panic("lockmgr: non-zero exclusive count");
#endif
lkp->lk_exclusivecount = 1;
COUNT(p, 1);
break;
@ -286,8 +307,10 @@ lockmgr(lkp, flags, interlkp, p)
/*
* Recursive lock.
*/
#if !defined(MAX_PERF)
if ((extflags & LK_CANRECURSE) == 0)
panic("lockmgr: locking against myself");
#endif
lkp->lk_exclusivecount++;
COUNT(p, 1);
break;
@ -316,23 +339,29 @@ lockmgr(lkp, flags, interlkp, p)
break;
lkp->lk_flags |= LK_HAVE_EXCL;
lkp->lk_lockholder = pid;
#if !defined(MAX_PERF)
if (lkp->lk_exclusivecount != 0)
panic("lockmgr: non-zero exclusive count");
#endif
lkp->lk_exclusivecount = 1;
COUNT(p, 1);
break;
case LK_RELEASE:
if (lkp->lk_exclusivecount != 0) {
#if !defined(MAX_PERF)
if (pid != lkp->lk_lockholder)
panic("lockmgr: pid %d, not %s %d unlocking",
pid, "exclusive lock holder",
lkp->lk_lockholder);
lkp->lk_exclusivecount--;
#endif
COUNT(p, -1);
if (lkp->lk_exclusivecount == 0) {
if (lkp->lk_exclusivecount == 1) {
lkp->lk_flags &= ~LK_HAVE_EXCL;
lkp->lk_lockholder = LK_NOPROC;
lkp->lk_exclusivecount = 0;
} else {
lkp->lk_exclusivecount--;
}
} else if (lkp->lk_flags & LK_SHARE_NONZERO) {
shareunlock(lkp, 1);
@ -349,8 +378,10 @@ lockmgr(lkp, flags, interlkp, p)
* check for holding a shared lock, but at least we can
* check for an exclusive one.
*/
#if !defined(MAX_PERF)
if (lkp->lk_lockholder == pid)
panic("lockmgr: draining against myself");
#endif
error = acquiredrain(lkp, extflags);
if (error)
@ -362,9 +393,11 @@ lockmgr(lkp, flags, interlkp, p)
break;
default:
#if !defined(MAX_PERF)
simple_unlock(&lkp->lk_interlock);
panic("lockmgr: unknown locktype request %d",
flags & LK_TYPE_MASK);
#endif
/* NOTREACHED */
}
if ((lkp->lk_flags & LK_WAITDRAIN) &&