Fix a thinko in draining of spin locks: bump waitcount in the spin case,
too. Remove some needless code duplication by adding a "drain" argument to the ACQUIRE() macro (compiler can [and does] optimize the constant conditional).
This commit is contained in:
thorpej
parent
3d71693ea7
commit
cb41412726
@ -1,4 +1,4 @@
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/* $NetBSD: kern_lock.c,v 1.22 1999/07/28 01:59:46 mellon Exp $ */
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/* $NetBSD: kern_lock.c,v 1.23 1999/07/28 19:29:39 thorpej Exp $ */
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/*-
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* Copyright (c) 1999 The NetBSD Foundation, Inc.
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@ -117,10 +117,12 @@ do { \
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/*
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* Acquire a resource.
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*/
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#define ACQUIRE(lkp, error, extflags, wanted) \
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#define ACQUIRE(lkp, error, extflags, drain, wanted) \
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if ((extflags) & LK_SPIN) { \
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int interlocked; \
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\
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if ((drain) == 0) \
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(lkp)->lk_waitcount++; \
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for (interlocked = 1;;) { \
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if (wanted) { \
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if (interlocked) { \
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@ -134,16 +136,24 @@ do { \
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interlocked = 1; \
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} \
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} \
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if ((drain) == 0) \
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(lkp)->lk_waitcount--; \
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KASSERT((wanted) == 0); \
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error = 0; /* sanity */ \
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} else { \
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for (error = 0; wanted; ) { \
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(lkp)->lk_waitcount++; \
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if ((drain)) \
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(lkp)->lk_flags |= LK_WAITDRAIN; \
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else \
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(lkp)->lk_waitcount++; \
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simple_unlock(&(lkp)->lk_interlock); \
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error = tsleep((void *)lkp, (lkp)->lk_prio, \
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/* XXX Cast away volatile. */ \
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error = tsleep((drain) ? &(lkp)->lk_flags : \
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(void *)(lkp), (lkp)->lk_prio, \
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(lkp)->lk_wmesg, (lkp)->lk_timo); \
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simple_lock(&(lkp)->lk_interlock); \
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(lkp)->lk_waitcount--; \
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if ((drain) == 0) \
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(lkp)->lk_waitcount--; \
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if (error) \
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break; \
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if ((extflags) & LK_SLEEPFAIL) { \
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@ -165,6 +175,14 @@ do { \
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(((lkp)->lk_flags & LK_SPIN) != 0 ? \
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((lkp)->lk_cpu == (cpu_id)) : ((lkp)->lk_lockholder == (pid)))
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#define WAKEUP_WAITER(lkp) \
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do { \
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if (((lkp)->lk_flags & LK_SPIN) == 0 && (lkp)->lk_waitcount) { \
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/* XXX Cast away volatile. */ \
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wakeup_one((void *)(lkp)); \
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} \
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} while (0)
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#if defined(LOCKDEBUG) /* { */
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#if defined(MULTIPROCESSOR) /* { */
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struct simplelock spinlock_list_slock = SIMPLELOCK_INITIALIZER;
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@ -341,7 +359,7 @@ lockmgr(lkp, flags, interlkp)
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/*
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* Wait for exclusive locks and upgrades to clear.
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*/
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ACQUIRE(lkp, error, extflags, lkp->lk_flags &
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ACQUIRE(lkp, error, extflags, 0, lkp->lk_flags &
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(LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE));
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if (error)
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break;
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@ -367,8 +385,7 @@ lockmgr(lkp, flags, interlkp)
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lkp->lk_flags &= ~LK_HAVE_EXCL;
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SETHOLDER(lkp, LK_NOPROC, LK_NOCPU);
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DONTHAVEIT(lkp);
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if (lkp->lk_waitcount)
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wakeup_one((void *)lkp);
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WAKEUP_WAITER(lkp);
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break;
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case LK_EXCLUPGRADE:
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@ -414,7 +431,7 @@ lockmgr(lkp, flags, interlkp)
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* drop to zero, then take exclusive lock.
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*/
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lkp->lk_flags |= LK_WANT_UPGRADE;
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ACQUIRE(lkp, error, extflags, lkp->lk_sharecount);
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ACQUIRE(lkp, error, extflags, 0, lkp->lk_sharecount);
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lkp->lk_flags &= ~LK_WANT_UPGRADE;
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if (error)
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break;
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@ -434,8 +451,8 @@ lockmgr(lkp, flags, interlkp)
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* lock, awaken upgrade requestor if we are the last shared
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* lock, then request an exclusive lock.
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*/
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if (lkp->lk_sharecount == 0 && lkp->lk_waitcount)
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wakeup_one((void *)lkp);
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if (lkp->lk_sharecount == 0)
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WAKEUP_WAITER(lkp);
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/* fall into exclusive request */
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case LK_EXCLUSIVE:
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@ -470,7 +487,7 @@ lockmgr(lkp, flags, interlkp)
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/*
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* Try to acquire the want_exclusive flag.
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*/
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ACQUIRE(lkp, error, extflags, lkp->lk_flags &
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ACQUIRE(lkp, error, extflags, 0, lkp->lk_flags &
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(LK_HAVE_EXCL | LK_WANT_EXCL));
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if (error)
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break;
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@ -478,7 +495,7 @@ lockmgr(lkp, flags, interlkp)
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/*
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* Wait for shared locks and upgrades to finish.
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*/
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ACQUIRE(lkp, error, extflags, lkp->lk_sharecount != 0 ||
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ACQUIRE(lkp, error, extflags, 0, lkp->lk_sharecount != 0 ||
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(lkp->lk_flags & LK_WANT_UPGRADE));
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lkp->lk_flags &= ~LK_WANT_EXCL;
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if (error)
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@ -521,8 +538,7 @@ lockmgr(lkp, flags, interlkp)
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lkp->lk_sharecount--;
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COUNT(lkp, p, cpu_id, -1);
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}
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if (lkp->lk_waitcount)
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wakeup_one((void *)lkp);
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WAKEUP_WAITER(lkp);
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break;
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case LK_DRAIN:
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@ -543,32 +559,13 @@ lockmgr(lkp, flags, interlkp)
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error = EBUSY;
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break;
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}
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if (lkp->lk_flags & LK_SPIN) {
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ACQUIRE(lkp, error, extflags,
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((lkp->lk_flags &
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(LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE)) ||
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lkp->lk_sharecount != 0 ||
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lkp->lk_waitcount != 0));
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} else {
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/*
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* This is just a special cause of the sleep case
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* in ACQUIRE(). We set WANTDRAIN instead of
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* incrementing waitcount.
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*/
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for (error = 0; ((lkp->lk_flags &
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(LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE)) ||
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lkp->lk_sharecount != 0 ||
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lkp->lk_waitcount != 0); ) {
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lkp->lk_flags |= LK_WAITDRAIN;
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simple_unlock(&lkp->lk_interlock);
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if ((error = tsleep((void *)&lkp->lk_flags,
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lkp->lk_prio, lkp->lk_wmesg, lkp->lk_timo)))
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return (error);
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if ((extflags) & LK_SLEEPFAIL)
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return (ENOLCK);
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simple_lock(&lkp->lk_interlock);
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}
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}
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ACQUIRE(lkp, error, extflags, 1,
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((lkp->lk_flags &
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(LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE)) ||
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lkp->lk_sharecount != 0 ||
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lkp->lk_waitcount != 0));
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if (error)
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break;
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lkp->lk_flags |= LK_DRAINING | LK_HAVE_EXCL;
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SETHOLDER(lkp, pid, cpu_id);
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HAVEIT(lkp);
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@ -585,8 +582,9 @@ lockmgr(lkp, flags, interlkp)
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flags & LK_TYPE_MASK);
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/* NOTREACHED */
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}
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if ((lkp->lk_flags & LK_WAITDRAIN) && ((lkp->lk_flags &
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(LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE)) == 0 &&
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if ((lkp->lk_flags & (LK_WAITDRAIN|LK_SPIN)) == LK_WAITDRAIN &&
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((lkp->lk_flags &
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(LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE)) == 0 &&
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lkp->lk_sharecount == 0 && lkp->lk_waitcount == 0)) {
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lkp->lk_flags &= ~LK_WAITDRAIN;
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wakeup_one((void *)&lkp->lk_flags);
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@ -1,4 +1,4 @@
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/* $NetBSD: lock.h,v 1.21 1999/07/27 23:45:13 thorpej Exp $ */
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/* $NetBSD: lock.h,v 1.22 1999/07/28 19:29:39 thorpej Exp $ */
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/*-
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* Copyright (c) 1999 The NetBSD Foundation, Inc.
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@ -140,6 +140,7 @@ struct lock {
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int lk_sharecount; /* # of accepted shared locks */
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short lk_exclusivecount; /* # of recursive exclusive locks */
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short lk_recurselevel; /* lvl above which recursion ok */
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int lk_waitcount; /* # of sleepers/spinners */
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/*
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* This is the sleep message for sleep locks, and a simple name
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@ -152,9 +153,6 @@ struct lock {
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/* pid of exclusive lock holder */
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pid_t lk_sleep_lockholder;
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/* # of processes sleeping for lock */
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int lk_sleep_waitcount;
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/* priority at which to sleep */
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int lk_sleep_prio;
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@ -171,7 +169,6 @@ struct lock {
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} lk_un;
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#define lk_lockholder lk_un.lk_un_sleep.lk_sleep_lockholder
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#define lk_waitcount lk_un.lk_un_sleep.lk_sleep_waitcount
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#define lk_prio lk_un.lk_un_sleep.lk_sleep_prio
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#define lk_timo lk_un.lk_un_sleep.lk_sleep_timo
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