/* $NetBSD: kern_lock.c,v 1.32 2000/06/10 18:44:43 sommerfeld Exp $ */ /*- * Copyright (c) 1999, 2000 The NetBSD Foundation, Inc. * All rights reserved. * * This code is derived from software contributed to The NetBSD Foundation * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility, * NASA Ames Research Center. * * This code is derived from software contributed to The NetBSD Foundation * by Ross Harvey. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by the NetBSD * Foundation, Inc. and its contributors. * 4. Neither the name of The NetBSD Foundation nor the names of its * contributors may be used to endorse or promote products derived * from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. */ /* * Copyright (c) 1995 * The Regents of the University of California. All rights reserved. * * This code contains ideas from software contributed to Berkeley by * Avadis Tevanian, Jr., Michael Wayne Young, and the Mach Operating * System project at Carnegie-Mellon University. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by the University of * California, Berkeley and its contributors. * 4. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * @(#)kern_lock.c 8.18 (Berkeley) 5/21/95 */ #include "opt_multiprocessor.h" #include "opt_lockdebug.h" #include "opt_ddb.h" #include #include #include #include #include #if defined(__HAVE_ATOMIC_OPERATIONS) #include #endif #if defined(LOCKDEBUG) #include /* * note that stdarg.h and the ansi style va_start macro is used for both * ansi and traditional c compiles. * XXX: this requires that stdarg.h define: va_alist and va_dcl */ #include void lock_printf __P((const char *fmt, ...)); int lock_debug_syslog = 0; /* defaults to printf, but can be patched */ #endif /* * Locking primitives implementation. * Locks provide shared/exclusive sychronization. */ #if defined(LOCKDEBUG) || defined(DIAGNOSTIC) /* { */ #if defined(MULTIPROCESSOR) /* { */ #if defined(__HAVE_ATOMIC_OPERATIONS) /* { */ #define COUNT_CPU(cpu_id, x) \ atomic_add_ulong(&curcpu()->ci_spin_locks, (x)) #else #define COUNT_CPU(cpu_id, x) /* not safe */ #endif /* __HAVE_ATOMIC_OPERATIONS */ /* } */ #else u_long spin_locks; #define COUNT_CPU(cpu_id, x) spin_locks += (x) #endif /* MULTIPROCESSOR */ /* } */ #define COUNT(lkp, p, cpu_id, x) \ do { \ if ((lkp)->lk_flags & LK_SPIN) \ COUNT_CPU((cpu_id), (x)); \ else \ (p)->p_locks += (x); \ } while (/*CONSTCOND*/0) #else #define COUNT(lkp, p, cpu_id, x) #endif /* LOCKDEBUG || DIAGNOSTIC */ /* } */ /* * Acquire a resource. */ #define ACQUIRE(lkp, error, extflags, drain, wanted) \ if ((extflags) & LK_SPIN) { \ int interlocked; \ \ if ((drain) == 0) \ (lkp)->lk_waitcount++; \ for (interlocked = 1;;) { \ if (wanted) { \ if (interlocked) { \ simple_unlock(&(lkp)->lk_interlock); \ interlocked = 0; \ } \ } else if (interlocked) { \ break; \ } else { \ simple_lock(&(lkp)->lk_interlock); \ interlocked = 1; \ } \ } \ if ((drain) == 0) \ (lkp)->lk_waitcount--; \ KASSERT((wanted) == 0); \ error = 0; /* sanity */ \ } else { \ for (error = 0; wanted; ) { \ if ((drain)) \ (lkp)->lk_flags |= LK_WAITDRAIN; \ else \ (lkp)->lk_waitcount++; \ /* XXX Cast away volatile. */ \ error = ltsleep((drain) ? &(lkp)->lk_flags : \ (void *)(lkp), (lkp)->lk_prio, \ (lkp)->lk_wmesg, (lkp)->lk_timo, \ &(lkp)->lk_interlock); \ if ((drain) == 0) \ (lkp)->lk_waitcount--; \ if (error) \ break; \ if ((extflags) & LK_SLEEPFAIL) { \ error = ENOLCK; \ break; \ } \ } \ } #define SETHOLDER(lkp, pid, cpu_id) \ do { \ if ((lkp)->lk_flags & LK_SPIN) \ (lkp)->lk_cpu = cpu_id; \ else \ (lkp)->lk_lockholder = pid; \ } while (/*CONSTCOND*/0) #define WEHOLDIT(lkp, pid, cpu_id) \ (((lkp)->lk_flags & LK_SPIN) != 0 ? \ ((lkp)->lk_cpu == (cpu_id)) : ((lkp)->lk_lockholder == (pid))) #define WAKEUP_WAITER(lkp) \ do { \ if (((lkp)->lk_flags & LK_SPIN) == 0 && (lkp)->lk_waitcount) { \ /* XXX Cast away volatile. */ \ wakeup_one((void *)(lkp)); \ } \ } while (/*CONSTCOND*/0) #if defined(LOCKDEBUG) /* { */ #if defined(MULTIPROCESSOR) /* { */ struct simplelock spinlock_list_slock = SIMPLELOCK_INITIALIZER; #define SPINLOCK_LIST_LOCK() \ __cpu_simple_lock(&spinlock_list_slock.lock_data) #define SPINLOCK_LIST_UNLOCK() \ __cpu_simple_unlock(&spinlock_list_slock.lock_data) #else #define SPINLOCK_LIST_LOCK() /* nothing */ #define SPINLOCK_LIST_UNLOCK() /* nothing */ #endif /* MULTIPROCESSOR */ /* } */ TAILQ_HEAD(, lock) spinlock_list = TAILQ_HEAD_INITIALIZER(spinlock_list); #define HAVEIT(lkp) \ do { \ if ((lkp)->lk_flags & LK_SPIN) { \ int s = splhigh(); \ SPINLOCK_LIST_LOCK(); \ /* XXX Cast away volatile. */ \ TAILQ_INSERT_TAIL(&spinlock_list, (struct lock *)(lkp), \ lk_list); \ SPINLOCK_LIST_UNLOCK(); \ splx(s); \ } \ } while (/*CONSTCOND*/0) #define DONTHAVEIT(lkp) \ do { \ if ((lkp)->lk_flags & LK_SPIN) { \ int s = splhigh(); \ SPINLOCK_LIST_LOCK(); \ /* XXX Cast away volatile. */ \ TAILQ_REMOVE(&spinlock_list, (struct lock *)(lkp), \ lk_list); \ SPINLOCK_LIST_UNLOCK(); \ splx(s); \ } \ } while (/*CONSTCOND*/0) #else #define HAVEIT(lkp) /* nothing */ #define DONTHAVEIT(lkp) /* nothing */ #endif /* LOCKDEBUG */ /* } */ #if defined(LOCKDEBUG) /* * Lock debug printing routine; can be configured to print to console * or log to syslog. */ void #ifdef __STDC__ lock_printf(const char *fmt, ...) #else lock_printf(fmt, va_alist) char *fmt; va_dcl #endif { va_list ap; va_start(ap, fmt); if (lock_debug_syslog) vlog(LOG_DEBUG, fmt, ap); else vprintf(fmt, ap); va_end(ap); } #endif /* LOCKDEBUG */ /* * Initialize a lock; required before use. */ void lockinit(lkp, prio, wmesg, timo, flags) struct lock *lkp; int prio; const char *wmesg; int timo; int flags; { memset(lkp, 0, sizeof(struct lock)); simple_lock_init(&lkp->lk_interlock); lkp->lk_flags = flags & LK_EXTFLG_MASK; if (flags & LK_SPIN) lkp->lk_cpu = LK_NOCPU; else { lkp->lk_lockholder = LK_NOPROC; lkp->lk_prio = prio; lkp->lk_timo = timo; } lkp->lk_wmesg = wmesg; /* just a name for spin locks */ } /* * Determine the status of a lock. */ int lockstatus(lkp) struct lock *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); } /* * XXX XXX kludge around another kludge.. * * vfs_shutdown() may be called from interrupt context, either as a result * of a panic, or from the debugger. It proceeds to call * sys_sync(&proc0, ...), pretending its running on behalf of proc0 * * We would like to make an attempt to sync the filesystems in this case, so * if this happens, we treat attempts to acquire locks specially. * All locks are acquired on behalf of proc0. * * If we've already paniced, we don't block waiting for locks, but * just barge right ahead since we're already going down in flames. */ /* * Set, change, or release a lock. * * Shared requests increment the shared count. Exclusive requests set the * LK_WANT_EXCL flag (preventing further shared locks), and wait for already * accepted shared locks and shared-to-exclusive upgrades to go away. */ int lockmgr(lkp, flags, interlkp) __volatile struct lock *lkp; u_int flags; struct simplelock *interlkp; { int error; pid_t pid; int extflags; cpuid_t cpu_id; struct proc *p = curproc; int lock_shutdown_noblock = 0; error = 0; simple_lock(&lkp->lk_interlock); if (flags & LK_INTERLOCK) simple_unlock(interlkp); extflags = (flags | lkp->lk_flags) & LK_EXTFLG_MASK; #ifdef DIAGNOSTIC /* { */ /* * Don't allow spins on sleep locks and don't allow sleeps * on spin locks. */ if ((flags ^ lkp->lk_flags) & LK_SPIN) panic("lockmgr: sleep/spin mismatch\n"); #endif /* } */ if (extflags & LK_SPIN) pid = LK_KERNPROC; else { if (p == NULL) { if (!doing_shutdown) { #ifdef DIAGNOSTIC panic("lockmgr: no context"); #endif } else { p = &proc0; if (panicstr && (!(flags & LK_NOWAIT))) { flags |= LK_NOWAIT; lock_shutdown_noblock = 1; } } } pid = p->p_pid; } cpu_id = cpu_number(); /* * Once a lock has drained, the LK_DRAINING flag is set and an * exclusive lock is returned. The only valid operation thereafter * is a single release of that exclusive lock. This final release * clears the LK_DRAINING flag and sets the LK_DRAINED flag. Any * further requests of any sort will result in a panic. The bits * selected for these two flags are chosen so that they will be set * in memory that is freed (freed memory is filled with 0xdeadbeef). * The final release is permitted to give a new lease on life to * the lock by specifying LK_REENABLE. */ if (lkp->lk_flags & (LK_DRAINING|LK_DRAINED)) { #ifdef DIAGNOSTIC /* { */ if (lkp->lk_flags & LK_DRAINED) panic("lockmgr: using decommissioned lock"); if ((flags & LK_TYPE_MASK) != LK_RELEASE || WEHOLDIT(lkp, pid, cpu_id) == 0) panic("lockmgr: non-release on draining lock: %d\n", flags & LK_TYPE_MASK); #endif /* DIAGNOSTIC */ /* } */ lkp->lk_flags &= ~LK_DRAINING; if ((flags & LK_REENABLE) == 0) lkp->lk_flags |= LK_DRAINED; } switch (flags & LK_TYPE_MASK) { case LK_SHARED: if (WEHOLDIT(lkp, pid, cpu_id) == 0) { /* * If just polling, check to see if we will block. */ if ((extflags & LK_NOWAIT) && (lkp->lk_flags & (LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE))) { error = EBUSY; break; } /* * Wait for exclusive locks and upgrades to clear. */ ACQUIRE(lkp, error, extflags, 0, lkp->lk_flags & (LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE)); if (error) break; lkp->lk_sharecount++; COUNT(lkp, p, cpu_id, 1); break; } /* * We hold an exclusive lock, so downgrade it to shared. * An alternative would be to fail with EDEADLK. */ lkp->lk_sharecount++; COUNT(lkp, p, cpu_id, 1); /* fall into downgrade */ case LK_DOWNGRADE: if (WEHOLDIT(lkp, pid, cpu_id) == 0 || lkp->lk_exclusivecount == 0) panic("lockmgr: not holding exclusive lock"); lkp->lk_sharecount += lkp->lk_exclusivecount; lkp->lk_exclusivecount = 0; lkp->lk_recurselevel = 0; lkp->lk_flags &= ~LK_HAVE_EXCL; SETHOLDER(lkp, LK_NOPROC, LK_NOCPU); DONTHAVEIT(lkp); WAKEUP_WAITER(lkp); break; case LK_EXCLUPGRADE: /* * If another process is ahead of us to get an upgrade, * then we want to fail rather than have an intervening * exclusive access. */ if (lkp->lk_flags & LK_WANT_UPGRADE) { lkp->lk_sharecount--; COUNT(lkp, p, cpu_id, -1); error = EBUSY; break; } /* fall into normal upgrade */ case LK_UPGRADE: /* * Upgrade a shared lock to an exclusive one. If another * shared lock has already requested an upgrade to an * exclusive lock, our shared lock is released and an * exclusive lock is requested (which will be granted * after the upgrade). If we return an error, the file * will always be unlocked. */ if (WEHOLDIT(lkp, pid, cpu_id) || lkp->lk_sharecount <= 0) panic("lockmgr: upgrade exclusive lock"); lkp->lk_sharecount--; COUNT(lkp, p, cpu_id, -1); /* * If we are just polling, check to see if we will block. */ 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) { /* * We are first shared lock to request an upgrade, so * request upgrade and wait for the shared count to * drop to zero, then take exclusive lock. */ lkp->lk_flags |= LK_WANT_UPGRADE; ACQUIRE(lkp, error, extflags, 0, lkp->lk_sharecount); lkp->lk_flags &= ~LK_WANT_UPGRADE; if (error) break; lkp->lk_flags |= LK_HAVE_EXCL; SETHOLDER(lkp, pid, cpu_id); HAVEIT(lkp); if (lkp->lk_exclusivecount != 0) panic("lockmgr: non-zero exclusive count"); lkp->lk_exclusivecount = 1; if (extflags & LK_SETRECURSE) lkp->lk_recurselevel = 1; COUNT(lkp, p, cpu_id, 1); break; } /* * Someone else has requested upgrade. Release our shared * lock, awaken upgrade requestor if we are the last shared * lock, then request an exclusive lock. */ if (lkp->lk_sharecount == 0) WAKEUP_WAITER(lkp); /* fall into exclusive request */ case LK_EXCLUSIVE: if (WEHOLDIT(lkp, pid, cpu_id)) { /* * Recursive lock. */ if ((extflags & LK_CANRECURSE) == 0 && lkp->lk_recurselevel == 0) { if (extflags & LK_RECURSEFAIL) { error = EDEADLK; break; } else panic("lockmgr: locking against myself"); } lkp->lk_exclusivecount++; if (extflags & LK_SETRECURSE && lkp->lk_recurselevel == 0) lkp->lk_recurselevel = lkp->lk_exclusivecount; COUNT(lkp, p, cpu_id, 1); break; } /* * If we are just polling, check to see if we will sleep. */ if ((extflags & LK_NOWAIT) && ((lkp->lk_flags & (LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE)) || lkp->lk_sharecount != 0)) { error = EBUSY; break; } /* * Try to acquire the want_exclusive flag. */ ACQUIRE(lkp, error, extflags, 0, lkp->lk_flags & (LK_HAVE_EXCL | LK_WANT_EXCL)); if (error) break; lkp->lk_flags |= LK_WANT_EXCL; /* * Wait for shared locks and upgrades to finish. */ ACQUIRE(lkp, error, extflags, 0, 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; SETHOLDER(lkp, pid, cpu_id); HAVEIT(lkp); if (lkp->lk_exclusivecount != 0) panic("lockmgr: non-zero exclusive count"); lkp->lk_exclusivecount = 1; if (extflags & LK_SETRECURSE) lkp->lk_recurselevel = 1; COUNT(lkp, p, cpu_id, 1); break; case LK_RELEASE: if (lkp->lk_exclusivecount != 0) { if (WEHOLDIT(lkp, pid, cpu_id) == 0) { if (lkp->lk_flags & LK_SPIN) { panic("lockmgr: processor %lu, not " "exclusive lock holder %lu " "unlocking", cpu_id, lkp->lk_cpu); } else { panic("lockmgr: pid %d, not " "exclusive lock holder %d " "unlocking", pid, lkp->lk_lockholder); } } if (lkp->lk_exclusivecount == lkp->lk_recurselevel) lkp->lk_recurselevel = 0; lkp->lk_exclusivecount--; COUNT(lkp, p, cpu_id, -1); if (lkp->lk_exclusivecount == 0) { lkp->lk_flags &= ~LK_HAVE_EXCL; SETHOLDER(lkp, LK_NOPROC, LK_NOCPU); DONTHAVEIT(lkp); } } else if (lkp->lk_sharecount != 0) { lkp->lk_sharecount--; COUNT(lkp, p, cpu_id, -1); } WAKEUP_WAITER(lkp); break; case LK_DRAIN: /* * Check that we do not already hold the lock, as it can * never drain if we do. Unfortunately, we have no way to * check for holding a shared lock, but at least we can * check for an exclusive one. */ if (WEHOLDIT(lkp, pid, cpu_id)) panic("lockmgr: draining against myself"); /* * If we are just polling, check to see if we will sleep. */ 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; } ACQUIRE(lkp, error, extflags, 1, ((lkp->lk_flags & (LK_HAVE_EXCL | LK_WANT_EXCL | LK_WANT_UPGRADE)) || lkp->lk_sharecount != 0 || lkp->lk_waitcount != 0)); if (error) break; lkp->lk_flags |= LK_DRAINING | LK_HAVE_EXCL; SETHOLDER(lkp, pid, cpu_id); HAVEIT(lkp); lkp->lk_exclusivecount = 1; /* XXX unlikely that we'd want this */ if (extflags & LK_SETRECURSE) lkp->lk_recurselevel = 1; COUNT(lkp, p, cpu_id, 1); break; default: simple_unlock(&lkp->lk_interlock); panic("lockmgr: unknown locktype request %d", flags & LK_TYPE_MASK); /* NOTREACHED */ } if ((lkp->lk_flags & (LK_WAITDRAIN|LK_SPIN)) == 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_one((void *)&lkp->lk_flags); } /* * Note that this panic will be a recursive panic, since * we only set lock_shutdown_noblock above if panicstr != NULL. */ if (error && lock_shutdown_noblock) panic("lockmgr: deadlock (see previous panic)"); simple_unlock(&lkp->lk_interlock); return (error); } /* * Print out information about state of a lock. Used by VOP_PRINT * routines to display ststus about contained locks. */ void lockmgr_printinfo(lkp) __volatile struct lock *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 ", lkp->lk_wmesg, lkp->lk_exclusivecount); if (lkp->lk_flags & LK_SPIN) printf("processor %lu", lkp->lk_cpu); else printf("pid %d", lkp->lk_lockholder); } else printf(" not locked"); if ((lkp->lk_flags & LK_SPIN) == 0 && lkp->lk_waitcount > 0) printf(" with %d pending", lkp->lk_waitcount); } #if defined(LOCKDEBUG) /* { */ TAILQ_HEAD(, simplelock) simplelock_list = TAILQ_HEAD_INITIALIZER(simplelock_list); #if defined(MULTIPROCESSOR) /* { */ struct simplelock simplelock_list_slock = SIMPLELOCK_INITIALIZER; #define SLOCK_LIST_LOCK() \ __cpu_simple_lock(&simplelock_list_slock.lock_data) #define SLOCK_LIST_UNLOCK() \ __cpu_simple_unlock(&simplelock_list_slock.lock_data) #if defined(__HAVE_ATOMIC_OPERATIONS) /* { */ #define SLOCK_COUNT(x) \ atomic_add_ulong(&curcpu()->ci_simple_locks, (x)) #else #define SLOCK_COUNT(x) /* not safe */ #endif /* __HAVE_ATOMIC_OPERATIONS */ /* } */ #else u_long simple_locks; #define SLOCK_LIST_LOCK() /* nothing */ #define SLOCK_LIST_UNLOCK() /* nothing */ #define SLOCK_COUNT(x) simple_locks += (x) #endif /* MULTIPROCESSOR */ /* } */ #ifdef DDB /* { */ int simple_lock_debugger = 0; #define SLOCK_DEBUGGER() if (simple_lock_debugger) Debugger() #else #define SLOCK_DEBUGGER() /* nothing */ #endif /* } */ #ifdef MULTIPROCESSOR #define SLOCK_MP() lock_printf("on cpu %d\n", cpu_number()) #else #define SLOCK_MP() /* nothing */ #endif #define SLOCK_WHERE(str, alp, id, l) \ do { \ lock_printf(str); \ lock_printf("lock: %p, currently at: %s:%d\n", (alp), (id), (l)); \ SLOCK_MP(); \ if ((alp)->lock_file != NULL) \ lock_printf("last locked: %s:%d\n", (alp)->lock_file, \ (alp)->lock_line); \ if ((alp)->unlock_file != NULL) \ lock_printf("last unlocked: %s:%d\n", (alp)->unlock_file, \ (alp)->unlock_line); \ SLOCK_DEBUGGER(); \ } while (/*CONSTCOND*/0) /* * Simple lock functions so that the debugger can see from whence * they are being called. */ void simple_lock_init(alp) struct simplelock *alp; { #if defined(MULTIPROCESSOR) /* { */ __cpu_simple_lock_init(&alp->lock_data); #else alp->lock_data = __SIMPLELOCK_UNLOCKED; #endif /* } */ alp->lock_file = NULL; alp->lock_line = 0; alp->unlock_file = NULL; alp->unlock_line = 0; alp->lock_holder = 0; } void _simple_lock(alp, id, l) __volatile struct simplelock *alp; const char *id; int l; { cpuid_t cpu_id = cpu_number(); int s; s = splhigh(); /* * MULTIPROCESSOR case: This is `safe' since if it's not us, we * don't take any action, and just fall into the normal spin case. */ if (alp->lock_data == __SIMPLELOCK_LOCKED) { #if defined(MULTIPROCESSOR) /* { */ if (alp->lock_holder == cpu_id) { SLOCK_WHERE("simple_lock: locking against myself\n", alp, id, l); goto out; } #else SLOCK_WHERE("simple_lock: lock held\n", alp, id, l); goto out; #endif /* MULTIPROCESSOR */ /* } */ } #if defined(MULTIPROCESSOR) /* { */ /* Acquire the lock before modifying any fields. */ __cpu_simple_lock(&alp->lock_data); #else alp->lock_data = __SIMPLELOCK_LOCKED; #endif /* } */ alp->lock_file = id; alp->lock_line = l; alp->lock_holder = cpu_id; SLOCK_LIST_LOCK(); /* XXX Cast away volatile */ TAILQ_INSERT_TAIL(&simplelock_list, (struct simplelock *)alp, list); SLOCK_LIST_UNLOCK(); SLOCK_COUNT(1); out: splx(s); } int _simple_lock_try(alp, id, l) __volatile struct simplelock *alp; const char *id; int l; { cpuid_t cpu_id = cpu_number(); int s, rv = 0; s = splhigh(); /* * MULTIPROCESSOR case: This is `safe' since if it's not us, we * don't take any action. */ #if defined(MULTIPROCESSOR) /* { */ if ((rv = __cpu_simple_lock_try(&alp->lock_data)) == 0) { if (alp->lock_holder == cpu_id) SLOCK_WHERE("simple_lock_try: locking against myself\n", alp, id, l); goto out; } #else if (alp->lock_data == __SIMPLELOCK_LOCKED) { SLOCK_WHERE("simple_lock_try: lock held\n", alp, id, l); goto out; } alp->lock_data = __SIMPLELOCK_LOCKED; #endif /* MULTIPROCESSOR */ /* } */ /* * At this point, we have acquired the lock. */ rv = 1; alp->lock_file = id; alp->lock_line = l; alp->lock_holder = cpu_id; SLOCK_LIST_LOCK(); /* XXX Cast away volatile. */ TAILQ_INSERT_TAIL(&simplelock_list, (struct simplelock *)alp, list); SLOCK_LIST_UNLOCK(); SLOCK_COUNT(1); out: splx(s); return (rv); } void _simple_unlock(alp, id, l) __volatile struct simplelock *alp; const char *id; int l; { int s; s = splhigh(); /* * MULTIPROCESSOR case: This is `safe' because we think we hold * the lock, and if we don't, we don't take any action. */ if (alp->lock_data == __SIMPLELOCK_UNLOCKED) { SLOCK_WHERE("simple_unlock: lock not held\n", alp, id, l); goto out; } SLOCK_LIST_LOCK(); TAILQ_REMOVE(&simplelock_list, alp, list); SLOCK_LIST_UNLOCK(); SLOCK_COUNT(-1); alp->list.tqe_next = NULL; /* sanity */ alp->list.tqe_prev = NULL; /* sanity */ alp->unlock_file = id; alp->unlock_line = l; #if defined(MULTIPROCESSOR) /* { */ alp->lock_holder = LK_NOCPU; /* Now that we've modified all fields, release the lock. */ __cpu_simple_unlock(&alp->lock_data); #else alp->lock_data = __SIMPLELOCK_UNLOCKED; #endif /* } */ out: splx(s); } void simple_lock_dump() { struct simplelock *alp; int s; s = splhigh(); SLOCK_LIST_LOCK(); lock_printf("all simple locks:\n"); for (alp = TAILQ_FIRST(&simplelock_list); alp != NULL; alp = TAILQ_NEXT(alp, list)) { lock_printf("%p CPU %lu %s:%d\n", alp, alp->lock_holder, alp->lock_file, alp->lock_line); } SLOCK_LIST_UNLOCK(); splx(s); } void simple_lock_freecheck(start, end) void *start, *end; { struct simplelock *alp; int s; s = splhigh(); SLOCK_LIST_LOCK(); for (alp = TAILQ_FIRST(&simplelock_list); alp != NULL; alp = TAILQ_NEXT(alp, list)) { if ((void *)alp >= start && (void *)alp < end) { lock_printf("freeing simple_lock %p CPU %lu %s:%d\n", alp, alp->lock_holder, alp->lock_file, alp->lock_line); SLOCK_DEBUGGER(); } } SLOCK_LIST_UNLOCK(); splx(s); } #endif /* LOCKDEBUG */ /* } */